The ulnar artery, C, Plate 17, holds a direct and superficial course, from the ulnar border of the forearm through the wrist; and still remains superficial in the palm, where it forms the superficial palmar arch, F. From this arch arise three or four branches of considerable size, which are destined to supply the fingers. A little above the interdigital clefts, each of these digital arteries divides into two branches, which pass along the adjacent sides of two fingers—a mode of distribution which also characterises the digital branches of the median, b b, and ulnar nerves, e e. The superficial palmar arch of the ulnar vessel anastomoses with the deep arch of the radial vessel. The principal points of communication are, first, by the branch, (ramus profundus,) I, Plate 18, which passes between the muscles of the little finger to join the deep arch beneath the long flexor tendons. 2nd, by the branch (superficialis volae) which springs from the radial artery, A, Plate 17, and crosses the muscles of the ball of the thumb, to join the terminal branch of the superficial arch, F, Plate 17. 3rd, by another terminal branch of the superficial arch, which joins the arteries of the thumb, derived from the radial vessel, as seen at e, Plate 18.

The frequent anastomosis thus seen to take place between the branches of the radial, the ulnar, and the interosseous arteries in the hand, should be carefully borne in mind by the surgeon. The continuity of the three vessels by anastomosis, renders it very difficult to arrest a haemorrhage occasioned by a wound of either of them. It will be at once seen, that when a haemorrhage takes place from any of these larger vessels of the hand, the bleeding will not be commanded by the application of a ligature to either the radial, the ulnar, or the interosseous arteries in the forearm; and for this plain reason, viz., that though in the arm these arteries are separate, in the hand their communication renders them as one.

If a haemorrhage therefore take place from either of the palmar vessels, it will not be sufficient to place a ligature around the radial or the ulnar artery singly, for if F, Plate 17, bleeds, and in order to arrest that bleeding we tie the vessel C, Plate 17, still the vessel F will continue to bleed, in consequence of its communication with the vessel E, Plate 18, by the branch 1, Plate 18, and other branches above mentioned. If E, Plate 18, bleeds, a ligature applied to the vessel A, Plate 18, will not stop the flow of blood, because of the fact that E anastomoses with G, by the branch I and other branches, as seen in Plates 17 and 19.

Any considerable haemorrhage, therefore, which may be caused by a wound of the superficial or deep palmar arches, or their branches, and which we are unable to arrest by compression, applied directly to the patent orifices of the vessel, will in general require that a ligature be applied to both the radial and ulnar arteries at the wrist; and it occasionally happens that even this proceeding will not stop the flow of blood, for the interosseous arteries, which also communicate with the vessels of the hand, may still maintain the current of circulation through them. These interosseous arteries being branches of the ulnar artery, and being given off from the vessel at the bend of the elbow, if the bleeding be still kept up from the vessel wounded in the hand, after the ligature of the ulnar and radial arteries is accomplished, are in all probability the channels of communication, and in this case the brachial artery must be tied. A consideration of the above mentioned facts, proper to the normal distribution of the vessels of the upper extremity, will explain to the practitioner the cause of the difficulty which occasionally presents itself, as to the arrest of haemorrhage from the vessels of the hand. In addition to these facts he will do well to remember some other arrangements of these vessels, which are liable to occur; and upon these I shall offer a few observations.

While I view the normal disposition of the arteries of the arm as a whole, (and this view of the whole great fact is no doubt necessary, if we would take within the span and compass of the reason, all the lesser facts of which the whole is inclusive,) I find that as one main vessel (the brachial) divides into three lesser branches, (the ulnar, radial and interosseous,) so, therefore, when either of these three supplies the haemorrhage, and any difficulty arises preventing our having access at once to the open orifices of the wounded vessel, we can command the flow of blood by applying a ligature to the main trunk—the brachial. If this measure fail to command the bleeding, then we may conclude that the wounded vessel (whichever it happen to be, whether the radial, the ulnar, or the interosseous) arises from the brachial artery, higher up in the arm than that place whereat we applied the ligature. To this variety as to the place of origin, the ulnar, radial, and interosseous arteries are individually liable.

Again, as the single brachial artery divides into the three arteries of the forearm, and as these latter again unite into what may (practically speaking) be termed a single vessel in the hand, in consequence of their anastomosis, so it is obvious that in order to command a bleeding from any of the palmar arteries, we should apply a ligature upon each of the vessels of the forearm, or upon the single main vessel in the arm. When the former proceeding fails, we have recourse to the latter, and when this latter fails (for fail it will, sometimes,) we then reasonably arrive at the conclusion that some one of the three vessels of the forearm, springs higher up than the place of the ligature on the main brachial vessel.

But however varied as to the normal locality of their origin, at the bend of the elbow, these vessels of the forearm may at times manifest themselves, still one point is quite fixed and certain, viz., that they communicate with each other in the hand. Hence, therefore, it becomes evident, that in order to command, at once and effectually, a bleeding, either from the palmar arteries, or those of the forearm, we attain to a more sure and successful result, the nearer we approach the fountain-head and place a ligature on it—the brachial artery. It is true that to stop the circulation through the main vessel of the limb, is always attended with danger, and that such a proceeding is never to be adopted but as the lesser one of two great hazards. It is also true that to tie the main brachial artery for a haemorrhage of anyone of its terminal branches, may be doing too much, while a milder course may serve; or else that even our tying the brachial may not suffice, owing to a high distribution of the vessels of the arm, in the axilla, above the place of the ligature. Thus doubt as to the safest measure, viz., that which is sufficient and no more, enveils the proper place whereat to apply a ligature on the principal vessel; but whatever be the doubt as to this particular, there can be none attending the following rule of conduct, viz., that in all cases of haemorrhage, caused by wounds of the vessels of the upper limb, we should, if at all practicable, endeavour to stop the flow of blood from the divided vessels in the wound itself, by ligature or otherwise; and both ends of the divided vessel require to be tied. Whenever this may be done, we need not trouble ourselves concerning the anomaly in vascular distribution.

The superficial palmar arch, F, Plate 17, lies beneath the dense palmar fascia; and whenever matter happens to be pent up by this fascia, and it is necessary that an opening be made for its exit, the incision should be conducted at a distance from the locality of the vessel. When matter forms beneath the palmar fascia, it is liable, owing to the unyielding nature of this fibrous structure, to burrow upwards into the forearm, beneath the annular ligament D, Plates 17 and 18. All deep incisions made in the median line of the forepart of the wrist are liable to wound the median nerve B, Plate 17. When the thumb, together with its metacarpal bone, is being amputated, the radial artery E, Plate 19, which winds round near the head of that bone, may be wounded. It is possible, by careful dissection, to perform this operation without dividing the radial vessel.

DESCRIPTION OF PLATES 17, 18, & 19.

PLATE 17.

A. Radial artery.

B. Median nerve; b b b b, its branches to the thumb and fingers.

C. Ulnar artery, forming F, the superficial palmar arch.

D. Ulnar nerve; E e e, its continuation branching to the little and ring fingers, &c.

G. Pisiform bone.

H. Abductor muscle of the little finger.

I. Tendon of flexor carpi radialis muscle.

K. Opponens pollicis muscle.

L. Flexor brevis muscle of the little finger.

M. Flexor brevis pollicis muscle.

N. Abductor pollicis muscle.

OOOO. Lumbricales muscles.

P P P P. Tendons of the flexor digitorum sublimis muscle.

Q. Tendon of the flexor longus pollicis muscle.

R. Tendon of extensor metacarpi pollicis.

S. Tendons of extensor digitorum sublimis; P P P, their digital prolongations.

T. Tendon of flexor carpi ulnaris.

U. Union of the digital arteries at the tip of the finger.



Plate 17



PLATE 18.

A. Radial artery.

B. Tendons of the extensors of the thumb.

C. Tendon of extensor carpi radialis.

D. Annular ligament.

E. Deep palmar arch, formed by radial artery giving off e, the artery of the thumb.

F. Pisiform bone.

G. Ulnar artery, giving off the branch I to join the deep palmar arch E of the radial artery.

H. Ulnar nerve; h, superficial branches given to the fingers. Its deep palmar branch is seen lying on the interosseous muscles, M M.

K. Abductor minimi digiti.

L. Flexor brevis minimi digiti.

M. Palmar interosseal muscles.

N. Tendons of flexor digitorum sublimis and profundus, and the lumbricales muscles cut and turned down.

O. Tendon of flexor pollicis longus.

P. Carpal end of the metacarpal bone of the thumb.



Plate 18



PLATE 19. AAA. Tendons of extensor digitorum communis; A*, tendon overlying that of the indicator muscle.

B. Dorsal part of the annular ligament.

C. End of the radial nerve distributed over the back of the hand, to two of the fingers and the thumb.

D. Dorsal branch of the ulnar nerve supplying the back of the hand and the three outer fingers.

E. Radial artery turning round the carpal end of the metacarpal bone of the thumb.

F. Tendon of extensor carpi radialis brevis.

G. Tendon of extensor carpi radialis longus.

H. Tendon of third extensor of the thumb.

I. Tendon of second extensor of the thumb.

K. Tendon of extensor minimi digiti joining a tendon of extensor communis.



Plate 19



COMMENTARY ON PLATES 20 & 21.

THE RELATIVE POSITION OF THE CRANIAL, NASAL, ORAL, AND PHARYNGEAL CAVITIES, &c.

On making a section (vertically through the median line) of the cranio-facial and cervico-hyoid apparatus, the relation which these structures bear to each other in the osseous skeleton reminds me strongly of the great fact enunciated by the philosophical anatomists, that the facial apparatus manifests in reference to the cranial structures the same general relations which the hyoid apparatus bears to the cervical vertebrae, and that these relations are similar to those which the thoracic apparatus bears to the dorsal vertebrae. To this anatomical fact I shall not make any further allusions, except in so far as the acknowledgment of it shall serve to illustrate some points of surgical import.

The cranial chamber, A A H, Plate 20, is continuous with the spinal canal C. The osseous envelope of the brain, called calvarium, Z B, holds serial order with the cervical spinous processes, E I, and these with the dorsal spinous processes. The dura-matral lining membrane, A A A*, of the cranial chamber is continuous with the lining membrane, C, of the spinal canal. The brain is continuous with the spinal cord. The intervertebral foramina of the cervical spine are manifesting serial order with the cranial foramina. The nerves which pass through the spinal region of this series of foramina above and below C are continuous with the nerves which pass through the cranial region. The anterior boundary, D I, of the cervical spine is continuous with the anterior boundary, Y F, of the cranial cavity. And this common serial order of osseous parts—viz., the bodies of vertebrae, serves to isolate the cranio-spinal compartment from the facial and cervical passages. Thus the anterior boundary, Y F D I, of the cranio-spinal canal is also the posterior boundary of the facial and cervical cavities.

Now as the cranio-spinal chamber is lined by the common dura-matral membrane, and contains the common mass of nervous structure, thus inviting us to fix attention upon this structure as a whole, so we find that the frontal cavity, Z, the nasal cavity, X W, the oral cavity, 4, 5, S, the pharyngeal and oesophageal passages 8 Q, are lined by the common mucous membrane, and communicate so freely with each other that they may be in fact considered as forming a common cavity divided only by partially formed septa, such as the one, U V, which separates to some extent the nasal fossa from the oral fossa.

As owing to this continuity of structure, visible between the head and spine, we may infer the liability which the affections of the one region have to pass into and implicate the other, so likewise by that continuity apparent between all compartments of the face, fauces, oesophagus, and larynx, we may estimate how the pathological condition of the one region will concern the others.

The cranium, owing to its comparatively superficial and undefended condition, is liable to fracture. When the cranium is fractured, in consequence of force applied to its anterior or posterior surfaces, A or B, Plate 20, the fracture will, for the most part, be confined to the place whereat the force has been applied, provided the point opposite has not been driven against some resisting body at the same time. Thus when the point B is struck by a force sufficient to fracture the bone, while the point A is not opposed to any resisting body, then B alone will yield to the force applied; and fracture thus occurring at the point B, will have happened at the place where the applied force is met by the force, or weight, or inertia of the head itself. But when B is struck by any ponderous body, while A is at the same moment forced against a resisting body, then A is also liable to suffer fracture. If fracture in one place be attended with counter-fracture in another place, as at the opposite points A and B, then the fracture occurs from the force impelling, while the counter-fracture happens by the force resisting.

Now in the various motions which the cranium A A B performs upon the top of the cervical spine C, motions backwards, forwards, and to either side, it will follow that, taking C as a fixed point, almost all parts of the cranial periphery will be brought vertical to C in succession, and therefore whichever point happens at the moment to stand opposite to C, and has impelling force applied to it, then C becomes the point of resistance, and thus counter-fractures at the cranial base occur in the neighbourhood of C. When force is applied to the cranial vertex, whilst the body is in the erect posture, the top of the cervical spine, E D C, becomes the point of resistance. Or if the body fall from a height upon its cranial vertex, then the propelling force will take effect at the junction of the spine with the cranial base, whilst the resisting force will be the ground upon which the vertex strikes. In either case the cranial base, as well as the vertex, will be liable to fracture.

The anatomical form of the cranium is such as to obviate a frequent liability to fracture. Its rounded shape diffuses, as is the case with all rotund forms, the force which happens to strike upon it. The mode in which the cranium is set upon the cervical spine serves also to diffuse the pressure at the points where the two opposing forces meet—viz., at the first cervical vertebra E and the cranial basilar process F. This fact might be proved upon mechanical principle.

The tegumentary envelope of the head, as well as the dura-matral lining, serves to damp cranial vibration consequent upon concussion; while the sutural isolation of the several component bones of the cranium also prevents, in some degree, the extension of fractures and the vibrations of concussion. The contents of the head, like the contents of all hollow forms, receive the vibratory influence of force externally applied. The brain receives the concussion of the force applied to its osseous envelope; and when this latter happens to be fractured, the danger to life is not in proportion to the extent of the fracture here, any more than elsewhere in the skeleton fabric, but is solely in proportion to the amount of shock or injury sustained by the nervous centre.

When it is required to trephine any part of the cranial envelope, the points which should be avoided, as being in the neighbourhood of important bloodvessels, are the following—the occipital protuberance, B, within which the "torcular Herophili" is situated, and from this point passing through the median line of the vertex forwards to Z the frontal sinus, the trephine should not be applied, as this line marks the locality of the superior longitudinal sinus. The great lateral sinus is marked by the superior occipital ridge passing from the point B outwards to the mastoid process. The central point B of the side of the head, Plate 21, marks the locality of the root of the meningeal artery within the cranium, and from this point the vessel branches forwards and backwards over the interior of the cranium.

The nasal fossae are situated on either side of the median partition formed by the vomer and cartilaginous nasal septum. Both nasal fossae are open anteriorly and posteriorly; but laterally they do not, in the normal state of these parts, communicate. The two posterior nares answering to the two nasal fossae open into the upper part of the bag of the pharynx at 8, Plate 20, which marks the opening of the Eustachian tube.

The structures observable in both the nasal fossae absolutely correspond, and the foramina which open into each correspond likewise. All structures situated on either side of the median line are similar. And the structure which occupies the median line is itself double, or duality fused into symmetrical unity. The osseous nasal septum is composed of two laminae laid side by side. The spongy bones, X W, are attached to the outer wall of the nasal fossa, and are situated one above the other. These bones are three in number, the uppermost is the smallest. The outer wall of each naris is grooved by three fossae, called meatuses, and these are situated between the spongy bones. Each meatus receives one or more openings of various canals and cavities of the facial apparatus. The sphenoidal sinus near F opens into the upper meatus. The frontal, Z, and maxillary sinuses open into the middle meatus, and the nasal duct opens into the inferior sinus beneath the anterior inferior angle of the lower spongy bone, W.

In the living body the very vascular fleshy and glandular Schneiderian membrane which lines all parts of the nasal fossa almost completely fills this cavity. When polypi or other growths occupy the nasal fossae, they must gain room at the expense of neighbouring parts. The nasal duct may have a bent probe introduced into it by passing the instrument along the outer side of the floor of the nasal fossa as far back as the anterior inferior angle of the lower spongy bone, W, at which locality the duct opens. An instrument of sufficient length, when introduced into the nostrils in the same direction, will, if passed backwards through the posterior nares, reach the opening of the Eustachian tube, 8.

While the jaws are closed, the tongue, R, Plate 20, occupies the oral cavity almost completely. When the jaws are opened they form a cavity between them equal in capacity to the degree at which they are sundered from each other. The back of the pharynx can be seen when the jaws are widely opened if the tongue be depressed, as R, Plate 20. The hard palate, U, which forms the roof of the mouth, is extended further backwards by the soft palate, V, which hangs as the loose velum of the throat between the nasal fossae above and the fauces below. Between the velum palati, V, and the root of the tongue, we may readily discern, when the jaws are open, two ridges of arching form, 5, 6, on either side of the fauces. These prominent arches and their fellows are named the pillars of the fauces. The anterior pillar, 5, is formed by the submucous palato-glossus muscle; the posterior pillar, 6, is formed by the palato-pharyngeus muscle. Between these pillars, 5 and 6, is situated the tonsil, S, beneath the mucous membrane. When the tonsils of opposite sides become inflamed and suppurate, an incision may be made into either gland without much chance of wounding the internal carotid artery; for, in fact, this vessel lies somewhat removed from it behind. In Plate 21, that point of the superior constrictor of the pharynx, marked D, indicates the situation of the tonsil gland; and a considerable interval will be seen to exist between D and the internal carotid vessel F.

If the head be thrown backwards the nasal and oral cavities will look almost vertically towards the pharyngeal pouch. When the juggler is about to "swallow the sword," he throws the head back so as to bring the mouth and fauces in a straight line with the pharynx and oesophagus. And when the surgeon passes the probang or other instruments into the oesophagus, he finds it necessary to give the head of the person on whom he operates the same inclination backwards. When instruments are being passed into the oesophagus through the nasal fossa, they are not so likely to encounter the rima glottidis below the epiglottis, 9, as when they are being passed into the oesophagus by the mouth. The glottis may be always avoided by keeping the point of the instrument pressing against the back of the pharynx during its passage downwards.

When in suspended animation we endeavour to inflate the lungs through the nose or mouth, we should press the larynx, 10, 11,12, backwards against the vertebral column, so as to close the oesophageal tube.

DESCRIPTION OF PLATES 20 & 21.

PLATE 20.

A A. The dura-matral falx; A*, its attachment to the tentorium.

B. Torcular Herophili.

C. Dura-mater lining the spinal canal.

D D*. Axis vertebra.

E E*. Atlas vertebra.

F F*. Basilar processes of the sphenoid and occipital bones.

G. Petrous part of the temporal bone.

H. Cerebellar fossa.

I I*. Seventh cervical vertebra.

K K*. First rib surrounding the upper part of the pleural sac.

L L*. Subclavian artery of the right side overlying the pleural sac.

M M*. Right subclavian vein.

N. Right common carotid artery cut at its origin.

O. Trachea.

P. Thyroid body.

Q. Oesophagus.

R. Genio-hyo-glossus muscle.

S. Left tonsil beneath the mucous membrane.

T. Section of the lower maxilla.

U. Section of the upper maxilla.

V. Velum palati in section.

W. Inferior spongy bone.

X. Middle spongy bone.

Y. Crista galli of oethmoid bone.

Z. Frontal sinus.

2. Anterior cartilaginous part of nasal septum.

3. Nasal bone.

4. Last molar tooth of the left side of lower jaw.

5. Anterior pillar of the fauces.

6. Posterior pillar of the fauces.

7. Genio-hyoid muscle.

8. Opening of Eustachian tube.

9. Epiglottis.

10. Hyoid bone.

11. Thyroid bone.

12. Cricoid bone.

13. Thyroid axis.

14. Part of anterior scalenus muscle.

15. Humeral end of the clavicle.

16. Part of posterior scalenus muscle.



Plate 20

PLATE 21.

A. Zygoma.

B. Articular glenoid fossa of temporal bone.

C. External pterygoid process lying on the levator and tensor palati muscles.

D. Superior constrictor of pharynx.

E. Transverse process of the Atlas.

F. Internal carotid artery. Above the point F, is seen the glosso-pharyngeal nerve; below F, is seen the hypoglossal nerve.

G. Middle constrictor of pharynx.

H. Internal jugular vein.

I. Common carotid cut across.

K. Rectus capitis major muscle.

L. Inferior constrictor of pharynx.

M. Levator anguli scapulae muscle.

N. Posterior scalenus muscle.

O. Anterior scalenus muscle.

P. Brachial plexus of nerves.

Q. Trachea.

R R*. Subclavian artery.

S. End of internal jugular vein.

T. Bracheo-cephalic artery.

U U*. Roots of common carotid arteries.

V. Thyroid body.

W. Thyroid cartilage.

X. Hyoid bone.

Y. Hyo-glossus muscle.

Z. Upper maxillary bone.

2. Inferior maxillary branch of fifth cerebral nerve.

3. Digastric muscle cut.

4. Styloid process.

5. External carotid artery.

6 6. Lingual artery.

7. Roots of cervical plexus of nerves.

8. Thyroid axis; 8*, thyroid artery, between which and Q, the trachea, is seen the inferior laryngeal nerve.

9. Omo-hyoid muscle cut.

10. Sternal end of clavicle.

11. Upper rings of trachea, which may with most safety be divided in tracheotomy.

12. Cricoid cartilage.

13. Crico-thyroid interval where laryngotomy is performed.

14. Genio-hyoid muscle.

15. Section of lower maxilla.

16. Parotid duct.

17. Lingual attachment of styloglossus muscle, with part of the gustatory nerve seen above it.



Plate 21



COMMENTARY ON PLATE 22.

THE RELATIVE POSITION OF THE SUPERFICIAL ORGANS OF THE THORAX AND ABDOMEN.

In the osseous skeleton, the thorax and abdomen constitute a common compartment. We cannot, while we contemplate this skeleton, isolate the one region from the other by fact or fancy. The only difference which I can discover between the regions called thorax and abdomen, in the osseous skeleton, (considering this body morphologically,) results, simply, from the circumstance that the ribs, which enclose thoracic space, have no osseous counterparts in the abdomen enclosing abdominal space, and this difference is merely histological. In man and the mammalia the costal arches hold relation with the pulmonary organs, and these costae fail at that region where the ventral organs are located. In birds, and many reptiles, the costal arches enclose the common thoracico-abdominal region, as if it were a common pulmonary region. In fishes the costal arches enclose the thoracico-abdominal region, just as if it were a common abdominal region. I merely mention these general facts to show that costal enclosure does not actually serve to isolate the thorax from the abdomen in the lower classes of animals; and on turning to the human form, I find that this line of separation between the two compartments is so very indefinite, that, as pathologists, we are very liable to err in our diagnosis between the diseased and the healthy organs of either region, as they lie in relation with the moveable diaphragm or septum in the living body. The contents of the whole trunk of the body from the top of the sternum to the perineum are influenced by the respiratory motions; and it is most true that the diaphragmatic line, H F H*, is alternately occupied by those organs situated immediately above and below it during the performance of these motions, even in health.

The organs of the thoracic region hold a certain relation to each other and to the thoracic walls. The organs of the abdomen hold likewise a certain relation to each other and to the abdominal parietes. The organs of both the thorax and the abdomen have a certain relation to each other, as they lie above and below the diaphragm. In dead nature these relations are fixed and readily ascertainable, but in living, moving nature, the organs influence this relative position, not only of each other, but also of that which they bear to the cavities in which they are contained. This change of place among the organs occurs in the normal or healthy state of the living body, and, doubtless, raises some difficulty in the way of our ascertaining, with mathematical precision, the actual state of the parts which we question, by the physical signs of percussion and auscultation. In disease this change of place among these organs is increased, and the difficulty of making a correct diagnosis is increased also in the same ratio. For when an emphysematous lung shall fully occupy the right thoracic side from B to L, then G, the liver, will protrude considerably into the abdomen beneath the right asternal ribs, and yet will not be therefore proof positive that the liver is diseased and abnormally enlarged. Whereas, on the other hand, when G, the liver, is actually diseased, it may occupy a situation in the right side as high as the fifth or sixth ribs, pushing the right lung upwards as high as that level; and, therefore, while percussion elicits a dull sound over this place thus occupied, such sound will not be owing to a hepatized lung, but to the absence of the lung caused by the presence of the liver.

In the healthy adult male body, Plate 22, the two lungs, D D*, whilst in their ordinary expanded state, may be said to range over all that region of the trunk of the body which is marked by the sternal and asternal ribs. The heart, E, occupies the thoracic centre, and part of the left thoracic side. The heart is almost completely enveloped in the two lungs. The only portion of the heart and pericardium, which appears uncovered by the lung on opening the thorax, is the base of the right ventricle, E, situated immediately behind the lower end of the sternum, where this bone is joined by the cartilages of the sixth and seventh ribs. The lungs range perpendicularly from points an inch above B, the first rib, downwards to L, the tenth rib, and obliquely downwards and backwards to the vertebral ends of the last ribs. This space varies in capacity, according to the degree in which the lungs are expanded within it. The increase in thoracic space is attained, laterally, by the expansion of the ribs, C I; and vertically, by the descent of the diaphragm, H, which forces downwards the mass of abdominal viscera. The contraction of thoracic space is caused by the approximation of all the ribs on each side to each other; and by the ascent of the diaphragm. The expansion of the lungs around the heart would compress this organ, were it not that the costal sides yield laterally while the diaphragm itself descends. The heart follows the ascent and descent of the diaphragm, both in ordinary and forced respiration.

But however much the lungs vary in capacity, or the heart as to position in the respiratory motions, still the lungs are always closely applied to the thoracic walls. Between the pleura costalis and pulmonalis there occurs no interval in health. The thoracic parietes expand and contract to a certain degree; and to that same degree, and no further, do the lungs within the thorax expand and contract. By no effort of expiration can the animal expel all the air completely from its lungs, since by no effort of its own, can it contract thoracic space beyond the natural limit. On the other hand, the utmost degree of expansion of which the lungs are capable, exactly equals that degree in which the thoracic walls are dilatable by the muscular effort; and, therefore, between the extremes of inspiration and expiration, the lungs still hold closely applied to the costal parietes. The air within the lungs is separated from the air external to the thorax, by the thoracic parietes. The air within and external to the lungs communicate at the open glottis. When the glottis closes and cuts off the communication, the respiratory act ceases—the lungs become immovable, and the thoracic walls are (so far as the motions of respiration are concerned) rendered immovable also. The muscles of respiration cannot, therefore, produce a vacuum between the pulmonic and costal pleura, either while the external air has or has not access to the lungs. Upon this fact the mechanism of respiration mainly depends; and we may see a still further proof of this in the circumstance that, when the thoracic parietes are pierced, so as to let the external air into the cavity of the pleura, the lung collapses and the thoracic side ceases to exert an expansile influence over the lung. When in cases of fracture of the rib the lung is wounded, and the air of the lung enters the pleura, the same effect is produced as when the external air was admitted through an opening in the side.

When serous or purulent effusion takes place within the cavity of the pleura, the capacity of the lung becomes lessened according to the quantity of the effusion. It is more reasonable to expect that the soft tissue of the lung should yield to the quantity of fluid within the pleural cavity, than that the rigid costal walls should give way outwardly; and, therefore, it seldom happens that the practitioner can discover by the eye any strongly-marked difference between the thoracic walls externally, even when a considerable quantity of either serum, pus, or air, occupies the pleural sacs.

In the healthy state of the thoracic organs, a sound characteristic of the presence of the lung adjacent to the walls of the thorax may be elicited by percussion, or heard during the respiratory act through the stethoscope, over all that costal space ranging anteriorly between B, the first rib, and I K, the eight and ninth ribs. The respiratory murmur can be heard below the level of these ribs posteriorly, for the lung descends behind the arching diaphragm as far as the eleventh rib.

When fluid is effused into the pleural cavity, the ribs are not moved by the intercostal muscles opposite the place occupied by the fluid, for this has separated the lung from the ribs. The fluid has compressed the lung; and in the same ratio as the lung is prevented from expanding, the ribs become less moveable. The presence of fluid in the pleural sac is discoverable by dulness on percussion, and, as might be expected, by the absence of the respiratory murmur at that locality which the fluid occupies. Fluid, when effused into the pleural sac, will of course gravitate; and its position will vary according to the position of the patient. The sitting or standing posture will therefore suit best for the examination of the thorax in reference to the presence of fluid.

Though the lungs are closely applied to the costal sides at all times in the healthy state of these organs, still they slide freely within the thorax during the respiratory motions—forwards and backwards—over the serous pericardium, E, and upwards and downwards along the pleura costalis. The length of the adhesions which supervene upon pleuritis gives evidence of the extent of these motions. When the lung becomes in part solidified and impervious to the inspired air, the motions of the thoracic parietes opposite to the part are impeded. Between a solidified lung and one which happens to be compressed by effused fluid it requires no small experience to distinguish a difference, either by percussion or the use of the stethoscope. It is great experience alone that can diagnose hydro-pericardium from hypertrophy of the substance of the heart by either of these means.

The thoracic viscera gravitate according to the position of the body. The heart in its pericardial envelope sways to either side of the sternal median line according as the body lies on this or that side. The two lungs must, therefore, be alternately affected as to their capacity according as the heart occupies space on either side of the thorax. In expiration, the heart, E, is more uncovered by the shelving edges of the lungs than in inspiration. In pneumothorax of either of the pleural sacs the air compresses the lung, pushes the heart from its normal position, and the space which the air occupies in the pleura yields a clear hollow sound on percussion, whilst, by the ear or stethoscope applied to a corresponding part of the thoracic walls, we discover the absence of the respiratory murmur.

The transverse diameter of the thoracic cavity varies at different levels from above downwards. The diameter which the two first ribs, B B*, measure, is the least. That which is measured by the two eighth ribs, I I*, is the greatest. The perpendicular depth of the thorax, measured anteriorly, ranges from A, the top of the sternum, to F, the xyphoid cartilage. Posteriorly, the perpendicular range of the thoracic cavity measures from the spinous process of the seventh cervical vertebra above, to the last dorsal spinous process below. In full, deep-drawn inspiration in the healthy adult, the ear applied to the thoracic walls discovers the respiratory murmur over all the space included within the above mentioned bounds. After extreme expiration, if the thoracic walls be percussed, this capacity will be found much diminished; and the extreme limits of the thoracic space, which during full inspiration yielded a clear sound, indicative of the presence of the lung, will now, on percussion, manifest a dull sound, in consequence of the absence of the lung, which has receded from the place previously occupied.

Owing to the conical form of the thoracic space, the apex of which is measured by the first ribs, B B*, and the basis by I I*, it will be seen that if percussion be made directly from before, backwards, over the pectoral masses, R R*, the pulmonic resonance will not be elicited. When we raise the arms from the side and percuss the thorax between the folds of the axillae, where the serratus magnus muscle alone intervenes between the ribs and the skin, the pulmonic sound will answer clearly.

At the hypochondriac angles formed between the points F, L, N, on either side the lungs are absent both in inspiration and expiration. Percussion, when made over the surface of the angle of the right side, discovers the presence of the liver, G G*. When made over the median line, and on either side of it above the umbilicus, N, we ascertain the presence of the stomach, M M*. In the left hypochondriac angle, the stomach may also be found to occupy this place wholly.

Beneath the umbilicus, N, and on either side of it as far outwards as the lower asternal ribs, K L, thus ranging the abdominal parietes transversely, percussion discovers the transverse colon, O, P, O*. The small intestines, S S*, covered by the omentum, P*, occupy the hypogastric and iliac regions.

The organs situated within the thorax give evidence that they are developed in accordance to the law of symmetry. The lungs form a pair, one placed on either side of the median line. The heart is a double organ, formed of the right and left heart. The right lung differs from the left, inasmuch as we find the former divided into three lobes, while the latter has only two. That place which the heart now occupies in the left thoracic side is the place where the third or middle lobe of the left lung is wanting. In the abdomen we find that most of its organs are single. The liver, stomach, spleen, colon, and small intestine form a series of single organs: each of these may be cleft symmetrically. The kidneys are a pair.

The extent to which the ribs are bared in the figure Plate 22, marks exactly the form and transverse capacity of the thoracic walls. The diaphragm, H H*, has had a portion of its forepart cut off, to show how it separates the thin edges of both lungs above from the liver, G, and the stomach, M, below. These latter organs, although occupying abdominal space, rise to a considerable height behind K L, the asternal ribs, a fact which should be borne in mind when percussing the walls of the thorax and abdomen at this region.

DESCRIPTION OF PLATE 22.

A. Upper bone of the sternum.

B B*. Two first ribs.

C C*. Second pair of ribs.

D D*. Right and left lungs.

E. Pericardium, enveloping the heart—the right ventricle.

F. Lower end of the sternum.

G G*. Lobes of the liver.

H H*. Right and left halves of the diaphragm in section. The right half separating the right lung from the liver; the left half separating the left lung from the broad cardiac end of the stomach.

I I*. Eighth pair of ribs.

K K*. Ninth pair of ribs.

L L*. Tenth pair of ribs.

M M*. The stomach; M, its cardiac bulge; M*, its pyloric extremity.

N. The umbilicus.

OO*. The transverse colon.

P P*. The omentum, covering the transverse colon and small intestines.

Q. The gall bladder.

R R*. The right and left pectoral prominences.

S S*. Small intestines.



Plate 22



COMMENTARY ON PLATE 23.

THE RELATIVE POSITION OF THE DEEPER ORGANS OF THE THORAX AND THOSE OF THE ABDOMEN.

The size or capacity of the thorax in relation to that of the abdomen varies in the individual at different periods of life. At an early age, the thorax, compared to the abdomen, is less in proportion than it is at adult age. The digestive organs in early age preponderate considerably over the respiratory organs; whereas, on the contrary, in the healthy and well-formed adult, the thoracic cavity and organs of respiration manifest a greater relative proportion to the ventral cavity and organs. At the adult age, when sexual peculiarities have become fully marked, the thoracic organs of the male body predominate over those of the abdomen, whilst in the female form the ventral organs take precedence as to development and proportions. This diversity in the relative capacity of the thorax and abdomen at different stages of development, and also in persons of different sexes, stamps each individual with characteristic traits of physical conformation; and it is required that we should take into our consideration this normal diversity of character, while conducting our examinations of individuals in reference to the existence of disease.

The heart varies in some measure, not only as to size and weight, but also as to position, even in healthy individuals of the same age and sex. The level at which the heart is in general found to be situated in the thorax is that represented in PLATE 23, where the apex points to the sixth intercostal space on the left side above K, while the arch of the aorta rises to a level with C, the second costal cartilage. In some instances, the heart may be found to occupy a much lower position in the thorax than the one above mentioned, or even a much higher level. The impulse of the right ventricle, F, has been noticed occasionally as corresponding to a point somewhat above the middle of the sternum and the intercostal space between the fourth and fifth left costal cartilages; while in other instances its beating was observable as low down as an inch or more below the xiphoid cartilage, and these variations have existed in a state of health.

Percussion over the region of the heart yields a dull flat sound. The sound is dullest opposite the right ventricle, F; whilst above and to either side of this point, where the heart is overlapped by the anterior shelving edges of both lungs, the sound is modified in consequence of the lung's resonant qualities. The heart-sounds, as heard through the stethoscope, in valvular disease, will, of course, be more distinctly ascertained at the locality of F, the right ventricle, which is immediately substernal. While the body lies supine, the heart recedes from the forepart of the chest; and the lungs during inspiration expanding around the heart will render its sounds less distinct. In the erect posture, the heart inclines forwards and approaches the anterior wall of the thorax. When the heart is hypertrophied, the lungs do not overlap it to the same extent as when it is of its ordinary size. In the latter state, the elastic cushion of the lung muffles the heart's impulse. In the former state, the lung is pushed aside by the overgrown heart, the strong muscular walls of which strike forcibly against the ribs and sternum.

The thorax is separated from the abdomen by the moveable diaphragm. The heart, F E, lies upon the diaphragm, L L*. The liver, M, lies immediately beneath the right side of this muscular septum, L*, while the bulging cardiac end of the stomach, O, is in close contact with it on the left side, L. As these three organs are attached to the diaphragm—the heart by its pericardium, the stomach by the tube of the oesophagus, and the liver by its suspensory ligaments—it must happen that the diaphragm while descending and ascending in the motions of inspiration and expiration will communicate the same alternate motions to the organs which are connected with it.

In ordinary respiration the capacity of the thorax is chiefly affected by the motions of the diaphragm; and the relative position which this septum holds with regard to the thoracic and abdominal chambers will cause its motions of ascent and descent to influence the capacity of both chambers at the same time. When the lungs expand, they follow the descent of the diaphragm, which forces the abdominal contents downwards, and thus what the thorax gains in space the abdomen loses. When the lungs contract, the diaphragm ascends, and by this act the abdomen gains that space which the thorax loses. But the organs of the thoracic cavity perform a different office in the economy from those of the abdomen. The air which fills the lungs is soon again expired, whilst the ingesta of the abdominal viscera are for a longer period retained; and as the space, which by every inspiration the thorax gains from the abdomen, would cause inconvenient pressure on the distended organs of this latter cavity, so we find that to obviate this inconvenience, nature has constructed the anterior parietes of the abdomen of yielding material. The muscular parietes of the abdomen relax during every inspiration, and thus this cavity gains that space which it loses by the encroachment of the dilating lungs.

The mechanical principle upon which the abdominal chamber is constructed, enables it to adjust its capacity to such exigence or pressing necessity as its own visceral organs impose on it, from time to time; and the relation which the abdominal cavity bears to the thoracic chamber, enables it also to be compensatory to this latter. When the inspiratory thorax gains space from the abdomen, or when space is demanded for the increasing bulk of the alimentary canal, or for the enlarging pregnant uterus; or when, in consequence of disease, such as dropsical accumulation, more room is wanted, then the abdominal chamber supplies the demand by the anterior bulge or swell of its expansile muscular parietes.

The position of the heart itself is affected by the expansion of the lungs on either side of it. As the expanding lungs force the diaphragm downwards, the heart follows it, and all the abdominal viscera yield place to the descending thoracic contents. In strong muscular efforts the diaphragm plays an important part, for, previously to making forced efforts, the lungs are distended with air, so as to swell and render fixed the thoracic walls into which so many powerful muscles of the shoulders, the neck, back, and abdomen, are inserted; at the same time the muscular diaphragm L L*, becomes tense and unbent from its arched form, thereby contracting abdominal space, which now has no compensation for this loss of space, since the abdominal parietes are also rendered firm and unyielding. It is at this crisis of muscular effort that the abdominal viscera become impacted together; and, acting by their own elasticity against the muscular force, make an exit for themselves through the weakest parts of the abdominal walls, and thus herniae of various kinds are produced. The most common situations of abdominal herniae are at the inguinal regions, towards which the intestines, T T, naturally gravitate; and at these situations the abdominal parietes are weak and membranous.

The contents of a hernial protrusion through the abdominal parietes, correspond in general with those divisions of the intestinal tube, which naturally lie adjacent to the part where the rupture has taken place. In the umbilical hernia it is either the transverse colon S*, or some part of the small intestine occupying the median line, or both together, with some folds of the omentum, which will be found to form the contents of this swelling. When the diaphragm itself sustains a rupture in its left half, the upper portion of the descending colon, S, protrudes through the opening. A diaphragmatic hernia has not, so far as I am aware, been seen to occur in the right side; and this exemption from rupture of the right half of the diaphragm may be accounted for anatomically, by the fact that the liver, M, defends the diaphragm at this situation. The liver occupies the whole depth of the right hypochondrium; and intervenes between the diaphragm L*, and the right extremity of the transverse colon, S**.

The contents of a right inguinal hernia consist of the small intestine, T. The contents of the right crural hernia are formed by either the small intestine, T, or the intestinum caecum, S***. I have seen a few cases in which the caecum formed the right crural hernia. Examples are recorded in which the intestine caecum formed the contents of a right inguinal hernia. The left inguinal and crural herniae contain most generally the small intestine, T, of the left side.

The right lung, I*, is shorter than the left; for the liver, M, raises the diaphragm, L, to a higher level within the thorax, on the right side, than it does on the left. When the liver happens to be diseased and enlarged, it encroaches still more on thoracic space; but, doubtless, judging from the anatomical connexions of the liver, we may conclude that when it becomes increased in volume it will accommodate itself as much at the expense of abdominal space. The liver, in its healthy state and normal proportions, protrudes for an inch (more or less) below the margins of the right asternal ribs. The upper or convex surface of the liver rises beneath the diaphragm to a level corresponding with the seventh or sixth rib, but this position will vary according to the descent and ascent of the diaphragm in the respiratory movements. The ligaments by which the liver is suspended do not prevent its full obedience to these motions.

The left lung, I, descends to a lower level than the right; and the left diaphragm upon which it rests is itself supported by the cardiac end of the stomach. When the stomach is distended, it does not even then materially obstruct the expansion of the left lung, or the descent of the left diaphragm, for the abdominal walls relax and allow of the increasing volume of the stomach to accommodate itself. The spleen, R, is occasionally subject to an extraordinary increase of bulk; and this organ, like the enlarged liver and the distended stomach, will, to some extent, obstruct the movements of the diaphragm in the act of respiration, but owing to its free attachments it admits of a change of place. The abdominal viscera, one and all, admit of a change of place; the peculiar forms of those mesenteric bonds by which they are suspended, allow them to glide freely over each other; and this circumstance, together with the yielding nature of the abdominal parietes, allows the thoracic organs to have full and easy play in the respiratory movements performed by agency of the diaphragm.

The muscles of respiration perform with ease so long as the air has access to the lungs through the normal passage, viz., the trachea. While the principle of the thoracic pneumatic apparatus remains underanged, the motor powers perform their functions capably. The physical or pneumatic power acts in obedience to the vital or muscular power, while both stand in equilibrium; but the ascendancy of the one over the other deranges the whole thoracic machine. When the glottis closes by muscular spasm and excludes the external air, the respiratory muscles cease to exert a motor power upon the pulmonary cavity; their united efforts cannot cause a vacuum in thoracic space in opposition to the pressure of the external air. When, in addition to the natural opening of the glottis, a false opening is made in the side at the point K, the air within the lung at I, and external to it in the now open pleural cavity, will stand in equilibrio; the lung will collapse as having no muscular power by which to dilate itself, and the thoracic dilator muscles will cease to affect the capacity of the lung, so long as by their action in expanding the thoracic walls, the air gains access through the side to the pleural sac external to the lung.

Whether the air be admitted into the pleural sac, by an opening made in the side from without, or by an opening in the lung itself, the mechanical principle of the respiratory apparatus will be equally deranged. Pneumo-thorax will be the result of either lesion; and by the accumulation of air in the pleura the lung will suffer pressure. This pressure will be permanent so long as the air has no egress from the cavity of the pleura.

The permanent distention of the thoracic cavity, caused by the accumulation of air in the pleural sac, or by the diffusion of air through the interlobular cellular tissue consequent on a wound of the lung itself, will equally obstruct the breathing; and though the situation of the accumulated air is in fact anatomically different in both cases, yet the effect produced is similar. Interlobular pressure and interpleural pressure result in the same thing, viz., the permanent retention of the air external to the pulmonary cells, which, in the former case, are collapsed individually; and, in the latter case, in the mass. Though the emphysematous lung is distended to a size equal to the healthy lung in deep inspiration, yet we know that emphysematous distention, being produced by extrabronchial air accumulation, is, in fact, obstructive to the respiratory act. The emphysematous lung will, in the same manner as the distended pleural sac, depress the diaphragm and render the thoracic muscles inoperative. The foregoing observations have been made in reference to the effect of wounds of the thorax, the proper treatment of which will be obviously suggested by our knowledge of the state of the contained organs which have suffered lesion.



DESCRIPTION OF PLATE 23.

A. Upper end of the sternum.

B B.* First pair of ribs.

C C.* Second pair of ribs.

D. Aorta, with left vagus and phrenic nerves crossing its transverse arch.

E. Root of pulmonary artery.

F. Right ventricle.

G. Right auricle.

H. Vena cava superior, with right phrenic nerve on its outer border.

I I*. Right and left lungs collapsed, and turned outwards, to show the heart's outline.

K K*. Seventh pair of ribs.

L L*. The diaphragm in section.

M. The liver in section.

N. The gall bladder with its duct joining the hepatic duct to form the common bile duct. The hepatic artery is seen superficial to the common duct; the vena portae is seen beneath it. The patent orifices of the hepatic veins are seen on the cut surface of the liver.

O. The stomach.

P. The coeliac axis dividing into the coronary, splenic and hepatic arteries.

Q. Inferior vena cava.

R. The spleen.

S S* S**. The transverse colon, between which and the lower border of the stomach is seen the gastro-epiploic artery, formed by the splenic and hepatic arteries.

S***. Ascending colon in the right iliac region.

T. Convolutions of the small intestines distended with air.



Plate 23



COMMENTARY ON PLATE 24.

THE RELATIONS OF THE PRINCIPAL BLOODVESSELS TO THE VISCERA OF THE THORACICO-ABDOMINAL CAVITY.

The median line of the body is occupied by the centres of the four great systems of organs which serve in the processes of circulation, respiration, innervation, and nutrition. These organs being fashioned in accordance with the law of symmetry, we find them arranged in close connexion with the vertebrate centre of the osseous fabric, which is itself symmetrical. In this symmetrical arrangement of the main organs of the trunk of the body, a mechanical principle is prominently apparent; for as the centre is the least moveable and most protected region of the form, so have these vitally important structures the full benefit of this situation. The aortal trunk, G, of the arterial system is disposed along the median line, as well for its own safety as for the fitting distribution of those branches which spring symmetrically from either side of it to supply the lateral regions of the body.

The visceral system of bloodvessels is moulded upon the organs which they supply. As the thoracic viscera differ in form and functional character from those of the abdomen, so we find that the arterial branches which are supplied by the aorta to each set, differ likewise in some degree. In the accompanying figure, which represents the thoracic and abdominal visceral branches of the aorta taken in their entirety, this difference in their arrangement may be readily recognised. In the thorax, compared with the abdomen, we find that not only do the aortic branches differ in form according to the variety of those organs contained in either region, but that they differ numerically according to the number of organs situated in each. The main vessel itself, however, is common to both regions. It is the one thoracico-abdominal vessel, and this circumstance calls for the comparison, not only of the several parts of the great vessel itself, but of all the branches which spring from it, and of the various organs which lie in its vicinity in the thorax and abdomen, and hence we are invited to the study of these regions themselves connectedly.

In the thorax, the aorta, G G*, is wholly concealed by the lungs in their states both of inspiration and expiration. The first part of the aortic arch, as it springs from the left ventricle of the heart, is the most superficial, being almost immediately sub-sternal, and on a level with the sternal junctions of the fourth ribs. By applying the ear at this locality, the play of the aortic valves may be distinctly heard. From this point the aorta, G, rises and arches from before, backwards, to the left side of the spine, G*. The arch of the vessel lies more deeply between the two lungs than does its ventricular origin. The descending thoracic aorta lies still more deeply situated at the left side of the dorsal spine. At this latter situation it is in immediate contact with the posterior thick part of the left lung; whilst on its right are placed, L, the thoracic duct; I, the oesophagus; K, the vena azygos, and the vertebral column. In Plate 26 may be seen the relation which the superior vena cava, H, bears to the aortic arch, A.

In the span of the aortic arch will be found, H*, the left bronchus, together with the right branch of the pulmonary artery, and the right pulmonary veins. The pneumo-gastric and phrenic nerves descend on either side of the arch. The left pneumo-gastric nerve winds round beneath the arch at the point where the obliterated ductus arteriosus joins it. See Plates 12 & 26.

The pulmonary artery, B, Plates 1 & 2, lies close upon the fore part, and conceals the origin, of the systemic aorta. Whenever, therefore, the semilunar valves of either the pulmonary artery or the systemic aorta become diseased, it must be extremely difficult to distinguish by the sounds alone, during life, in which of the two the derangement exists. The origins of both vessels being at the fore part of the chest, it is in this situation, of course, that the state of their valves is to be examined. The descending part of the thoracic aorta, G*, being at the posterior part of the chest, and lying on the vertebral ends of the left thoracic ribs, will therefore require that we should examine its condition in the living body at the dorsal aspect of the thorax. As the arch of the aorta is directed from before backwards—that is, from the sternum to the spine, it follows that when an aneurism implicates this region of the vessel, the exact situation of the tumour must be determined by antero-posterior examination; and we should recollect, that though on the fore part of the chest the cartilages of the second ribs, where these join the sternum, mark the level of the aortic arch, on the back of the chest its level is to be taken from the vertebral ends of the third or fourth ribs. This difference is caused by the oblique descent of the ribs from the spine to the sternum. The first and second dorsal vertebrae, with which the first and second ribs articulate, are considerably above the level of the first and second pieces of the sternum.

In a practical point of view, the pulmonary artery possesses but small interest for us; and in truth the trunk of the systemic aorta itself may be regarded in the same disheartening consideration, forasmuch as when serious disease attacks either vessel, the "tree of life" may be said to be lopped at its root.

When an aneurism arises from the aortic arch it implicates those important organs which are gathered together in contact with itself. The aneurismal tumour may press upon and obstruct the bronchi, H H*; the thoracic duct, L; the oesophagus, I; the superior vena cava, H, Plate 26, or wholly obliterate either of the vagi nerves. The aneurism of the arch of the aorta may cause suffocation in two ways—viz., either by pressing directly on the tracheal tube, or by compressing and irritating the vagus nerve, whose recurrent branch will convey the stimulus to the laryngeal muscles, and cause spasmodic closure of the glottis. This anatomical fact also fully accounts for the constant cough which attends some forms of aortic aneurism. The pulmonary arteries and veins are also liable to obstruction from the tumour. This will occur the more certainly if the aneurism spring from the right or the inferior side of the arch, and if the tumour should not break at an early period, slow absorption, caused by pressure of the tumour, may destroy even the vertebral column, and endanger the spinal nervous centre. If the tumour spring from the left side or the fore part of the arch, it may in time force a passage through the anterior wall of the thorax.

The principal branches of the thoracic aorta spring from the upper part of its arch. The innominate artery, 2, is the first to arise from it; the left common carotid, 6, and the left subclavian artery, 5, spring in succession. These vessels being destined for the head and upper limbs, we find that the remaining branches of the thoracic aorta are comparatively diminutive, and of little surgical interest. The intercostal arteries occasionally, when wounded, call for the aid of the surgeon; these arteries, like all other branches of the aorta, are largest at their origin. Where these vessels spring from G, the descending thoracic aorta, they present considerable caliber; but at this inaccessible situation, they seldom or never call for surgical interference. As the intercostal arteries pass outwards, traversing the intercostal spaces with their accompanying nerves, they diminish in size. Each vessel divides at a distance of about two inches, more or less, from the spine; and the upper larger branch lies under cover of the inferior border of the adjacent rib. When it is required to perform the operation of paracentesis thoracis, this distribution of the vessel should be borne in mind; and also, that the farther from the spine this operation is performed, the less in size will the vessels be found. The intercostal artery is sometimes wounded by the fractured end of the rib, in which case, if the pleura be lacerated, an effusion of blood takes place within the thorax, compresses the lung, and obstructs respiration.

The thoracic aorta descends along the left side of the spine, as far as the last dorsal vertebra, at which situation the pillars of the diaphragm overarch the vessel. From this place the aorta passes obliquely in front of the five lumbar vertebrae, and on arriving opposite the fourth, it divides into the two common iliac branches. The aorta, for an extent included between these latter boundaries, is named the abdominal aorta, and from its fore part arise those branches, which supply the viscera of the abdomen.

The branches which spring from the abdominal aorta to supply the viscera of this region, are considerable, both as to their number and size. They are, however, of comparatively little interest in practice. To the anatomist they present many peculiarities of distribution and form worthy of notice, as, for example, their frequent anastomosis, their looping arrangement, and their large size and number compared with the actual bulk of the organs which they supply. As to this latter peculiarity, we interpret it according to the fact that here the vessels serve other purposes in the economy besides that of the support and repair of structure. The vessels are large in proportion to the great quantity of fluid matter secreted from the whole extent of the inner surface of this glandular apparatus—the gastro-intestinal canal, the liver, pancreas, and kidneys.

As anatomists, we are enabled, from a knowledge of the relative position of the various organs and bloodvessels of both the thorax and abdomen, to account for certain pathological phenomena which, as practitioners, we possess as yet but little skill to remedy. Thus it would appear most probable that many cases of anasarca of the lower limbs, and of dropsy of the belly, are frequently caused by diseased growths of the liver, P, obstructing the inferior vena cava, R, and vena portae, rather than by what we are taught to be the "want of balance between secreting and absorbing surfaces." The like occurrence may obstruct the gall-ducts, and occasion jaundice. Over-distention of any of those organs situated beneath the right hypochondrium, will obstruct neighbouring organs and vessels. Mechanical obstruction is doubtless so frequent a source of derangement, that we need not on many occasions essay a deeper search for explaining the mystery of disease.

In the right hypochondriac region there exists a greater variety of organs than in the left; and disease is also more frequent on the right side. Affections of the liver will consequently implicate a greater number of organs than affections of the spleen on the left side, for the spleen is comparatively isolated from the more important blood vessels and other organs.

The external surface of the liver, P, lies in contact with the diaphragm, N, the costal cartilages, M, and the upper and lateral parts of the abdominal parietes; and when the liver becomes the seat of abscess, this, according to its situation, will point and burst either into the thorax above, or through the side between or beneath the false ribs, M. The hepatic abscess has been known to discharge itself through the stomach, the duodenum, T, and the transverse colon, facts which are readily explained on seeing the close relationship which these parts hold to the under surface of the liver. When the liver is inflamed, we account for the gastric irritation, either from the inflammation having extended to the neighbouring stomach, or by this latter organ being affected by "reflex action." The hepatic cough is caused by the like phenomena disturbing the diaphragm, N, with which the liver, P, lies in close contact.

When large biliary concretions form in S, the gallbladder, or in the hepatic duct, Nature, failing in her efforts to discharge them through the common bile-duct, into the duodenum, T, sets up inflammation and ulcerative absorption, by aid of which processes they make a passage for themselves through some adjacent part of the intestine, either the duodenum or the transverse colon. In these processes the gall-bladder, which contains the calculus, becomes soldered by effused lymph to the neighbouring part of the intestinal tube, into which the stone is to be discharged, and thus its escape into the peritoneal sac is prevented. When the hepatic abscess points externally towards M, the like process isolates the matter from the cavities of the chest and abdomen.

In wounds of any part of the intestine, whether of X, the caecum, W, the sigmoid flexure of the colon, or Z, the small bowel, if sufficient time be allowed for Nature to establish the adhesive inflammation, she does so, and thus fortifies the peritoneal sac against an escape of the intestinal matter into it by soldering the orifice of the wounded intestine to the external opening. In this mode is formed the artificial anus. The surgeon on principle aids Nature in attaining this result.

DESCRIPTION OF PLATE 24.

A. The thyroid body.

B. The trachea.

C C*. The first ribs.

D D*. The clavicles, cut at their middle.

E. Humeral part of the great pectoral muscle, cut.

F. The coracoid process of the scapula.

G. The arch of the aorta. G*. Descending aorta in the thorax.

H. Right bronchus. H*. Left bronchus.

I. Oesophagus.

K. Vena azygos receiving the intercostal veins.

L. Thoracic duct.

M M*. Seventh ribs.

N N. The diaphragm, in section.

O. The cardiac orifice of the stomach.

P. The liver, in section, showing the patent orifices of the hepatic veins.

Q. The coeliac axis sending off branches to the liver, stomach, and spleen. The stomach has been removed, to show the looping anastomosis of these vessels around the superior and inferior borders of the stomach.

R. The inferior vena cava about to enter its notch in the posterior thick part of the liver, to receive the hepatic veins.

S. The gall-bladder, communicating by its duct with the hepatic duct, which is lying upon the vena portae, and by the side of the hepatic artery.

T. The pyloric end of the stomach, joining T*, the duodenum.

U. The spleen.

V V. The pancreas.

W. The sigmoid flexure of the colon.

X. The caput coli.

Y. The mesentery supporting the numerous looping branches of the superior mesenteric artery.

Z. Some coils of the small intestine.

2. Innominate artery.

3. Right subclavian artery.

4. Right common carotid artery.

5. Left subclavian artery.

6. Left common carotid artery.

7. Left axillary artery.

8. Coracoid attachment of the smaller pectoral muscle.

9. Subscapular muscle.

10. Coracoid head of the biceps muscle.

11. Tendon of the latissimus dorsi muscle.

12. Superior mesenteric artery, with its accompanying vein.

13. Left kidney.



Plate 24



COMMENTARY ON PLATE 25.

THE RELATION OF THE PRINCIPAL BLOODVESSELS OF THE THORAX AND ABDOMEN TO THE OSSEOUS SKELETON, ETC.

The arterial system of vessels assumes, in all cases, somewhat of the character of the forms upon which they are distributed, or of the organs which they supply. This mode of distribution becomes the more apparent, according as we rise from particulars to take a view of the whole. With the same ease that any piece of the osseous fabric, taken separately, may be known, so may any one artery, taken apart from the rest, be distinguished as to the place which it occupied, and the organs which it supplied in the economy. The vascular skeleton, whether taken as a whole or in parts, exhibits characteristics as apparent as are those of the osseous skeleton itself. The main bloodvessel, A B C, of the trunk of the body, possesses character, sui generis, just as the vertebral column itself manifests. The main arteries of the head or limbs are as readily distinguishable, the one from the other, as are the osseous fabrics of the head and limbs. The visceral arteries are likewise moulded upon the forms which they supply. But evidently the arterial system of vessels conforms most strictly with the general design of the osseous skeleton.

In Plate 25, viewed as a whole, we find that as the vertebral column stands central to the osseous skeleton, so does the aorta, A B C, take the centre of the arterial skeleton. As the ribs jut symmetrically from either side of the vertebral column, so do the intercostal arteries follow them from their own points of origin in the aorta. The one side of the osseous system is not more like the other than is the system of vessels on one side like that of the other. And in addition to this fact of a similarity of sides in the vascular as in the osseous skeleton, I also remark that both extremities of the aorta divide into branches which are similar to one another above and below, thereby conforming exactly with the upper and lower limbs, which manifest unmistakable points of analogy.

The branches which spring from the aortic arch above are destined to supply the head and upper limbs. They are, H, the innominate artery, and I K, the left common carotid and subclavian arteries. The branches which spring from the other extremity of the aorta are disposed for the support of the pelvis and lower limbs; they are the right and left common iliac arteries, L M. These vessels exhibit, at both ends of the main aortic trunk, a remarkable analogy; and as the knowledge of this fact may serve to lighten the dry and weary detail of descriptive anatomy, at the same time that it points directly to views of practical import, I may be allowed briefly to remark upon it as follows:—

The vessels which spring from both ends of the aorta, as seen in Plate 25, are represented in what is called their normal character—that is, while three vessels, H I K, spring separately from the aortic arch above, only two vessels, L and M, arise from the aorta below. Let the anatomist now recall to mind the "peculiarities" which at times appear amongst the vessels, H I K, above, and he will find that some of them absolutely correspond to the normal arrangement of the vessels, L M, below. And if he will consider the "peculiarities" which occur to the normal order of the vessels, L M, below, he will find that some of these correspond exactly to the normal order of the vessels above. Thus, when I K of the left side join into a common trunk, this resembles the innominate artery, H, of the right side, and then both these vessels perfectly correspond with the two common iliac arteries below. When, on the other hand, L and M, the common iliac arteries, divide, immediately after leaving the aortic trunk, into two pairs of branches, they correspond to the abnormal condition of the vessels, H I K, above; where H, immediately after leaving the aortic arch, divides into two branches, like I K. With this generalization upon the normal and abnormal facts of arrangement, exhibited among the vessels arising from both ends of the aorta, I furnish to the reader the idea that the vessels, H I K, above may present of the same figure as the vessels, L M, below, and these latter may assume the character of H I K, above. Whenever, therefore, either set of vessels becomes the subject of operation, such as having a ligature applied to them, we must be prepared to meet the "varieties."

The veins assume an arrangement similar to that of the arteries, and the above remarks will therefore equally apply to the veins. In the same way as the arteries, H I K, may present in the condition of two common or brachio-cephalic trunks, and thereby simulate the condition of the common iliac arteries, so we find that the normal forms of the veins above and below actually and permanently exhibit this very type. The brachio-cephalic veins, D B, Plate 26, exactly correspond to each other, and to the common iliac veins, S T; and as these latter correspond precisely with the common iliac arteries, so may we infer that the original or typical condition of the vessels I K, Plate 25, is a brachia-cephalic or common-trunk union corresponding with its brachio-cephalic vein. When the vessels, I K, therefore present of the brachio-cephalic form as the vessel H, we have a perfect correspondence between the two extremes of the aorta, both as regards the arteries arising from it, and the veins which accompany these arteries; and this condition of the vascular skeleton I regard as the typical uniformity. The separate condition of the vessels I K, notwithstanding the frequency of the occurrence of such, may be considered as a special variation from the original type.

The length of the aorta is variable in two or more bodies; and so, likewise, is the length of the trunk of each of those great branches which springs from its arch above, and of those into which it divides below, The modes in which these variations as to length occur, are numerous. The top of the arch of the aorta is described as being in general on a level with the cartilages of the second ribs, from which point it descends on the left side of the spinal column; and after having wound gradually forwards to the forepart of the lumbar spine at C, divides opposite to the fourth lumbar vertebra into the right and left common iliac arteries. The length of that portion of the aorta which is called thoracic, is determined by the position of the pillars of the diaphragm F, which span the vessel; and from this point to where the aorta divides into the two common iliac arteries, the main vessel is named abdominal. The aorta, from its arch to its point of division on the lumbar vertebrae, gradually diminishes in caliber, according to the number and succession of the branches derived from it.

The varieties as to length exhibited by the aorta itself, and by the principal branches which spring from it, occur under the following mentioned conditions:—When the arch of the aorta rises above or sinks below its ordinary position or level,—namely, the cartilages of the second ribs, as seen in Plate 25,—it varies not only its own length, but also that of the vessels H I K; for if the arch of the aorta rises above this level, the vessels H I K become shortened; and as the arch sinks below this level, these vessels become lengthened. Even when the aortic arch holds its proper level in the thorax, still the vessels H I K may vary as to length, according to the height to which they rise in the neck previously to their division. When the aorta sinks below its proper level at the same time that the vessels H I K rise considerably above that point at which they usually arch or divide in the neck, then of course their length becomes greatly increased. When, on the other hand, the aortic arch rises above its usual level, whilst the vessels H I K arch and divide at a low position in the neck, then their length becomes very much diminished. The length of the artery H may be increased even though the arch of the aorta holds its proper level, and though the vessels H I K occupy their usual position in the neck; for it is true that the vessel H may spring from a point of the aortic arch A nearer to the origin of this from the ventricle of the heart, whilst the vessel I may be shortened, owing to the fact of its arising from some part of H, the innominate vessel. All these circumstances are so obvious, that they need no comment, were it not for the necessity of impressing the surgeon with the fact that uncertainty as to a successful result must always attach to his operation of including in a ligature either of the vessels H I K, so as to affect an aneurismal tumour.

Now whilst the length of the aorta and that of the principal branches springing from its arch may be varied according to the above-mentioned conditions, so may the length of the aorta itself, and of the two common iliac vessels, vary according to the place whereat the aorta, C, bifurcates. Or, even when this point of division is opposite the usual vertebra,—viz., the fourth lumbar,—still the common iliac vessels may be short or long, according to the place where they divide into external and internal iliac branches. The aorta may bifurcate almost as high up as where the pillars of the diaphragm overarch it, or as low down as the fifth lumbar vertebra. The occasional existence of a sixth lumbar vertebra also causes a variety in the length, not only of the aorta, but of the two common iliac vessels and their branches.[Footnote]

[Footnote: Whatever may be the number of variations to which the branches arising from both extremes of the aorta are liable, all anatomists admit that the arrangement of these vessels, as exhibited in Plate 25, is by far the most frequent. The surgical anatomist, therefore, when planning his operation, takes this arrangement as the standard type. Haller asserts this order of the vessels to be so constant, that in four hundred bodies which he examined, he found only one variety—namely, that in which the left vertebral artery arose from the aorta. Of other varieties described by authors, he observes—"Rara vero haec omnia esse si dixero cum quadringenta nunc cadavera humana dissecuerim, fidem forte inveniam." (Iconum Anatom.) This variety is also stated by J. F. Meckel (Handbuch der Mensch Anat.), Soemmerring (De Corp. Hum Fabrica), Boyer (Tr. d'Anat.), and Mr. Harrison (Surg. Anal. of Art.), to be the most frequent. Tiedemann figures this variety amongst others (Tabulae Arteriarum). Mr. Quain regards as the most frequent change which occurs in the number of the branches of the aortic arch, "that in which the left carotid is derived from the innominate." (Anatomy of the Arteries, &c.) A case is recorded by Petsche (quoted in Haller), in which he states the bifurcation of the aorta to have taken place at the origin of the renal arteries: (query) are we to suppose that the renal arteries occupied their usual position? Cruveilhier records a case (Anal. Descript.) in which the right common iliac was wanting, in consequence of having divided at the aorta into the internal and external iliac branches. Whether the knowledge of these and numerous other varieties of the arterial system be of much practical import to the surgeon, he will determine for himself. To the scientific anatomist, it must appear that the main object in regard to them is to submit them to a strict analogical reasoning, so as to demonstrate the operation of that law which has produced them. To this end I have pointed to that analogy which exists between the vessels arising from both extremities of the aorta. "Itaque convertenda plane est opera ad inquirendas et notandas rerum similitudines et analoga tam integralibus quam partibus; illae enim sunt, quae naturam uniunt, et constituere scientias incipiunt." "Natura enim non nisi parendo vincitur; et quod in contemplatione instar causae est; id in operatione instar regulae est." (Novum Organum Scientiarum, Aph. xxvii-iii, lib. i.)]

The difference between the perpendicular range of the anterior and posterior walls of the thoracic cavity may be estimated on a reference to Plate 25, in which the xyphoid cartilage, E, joined to the seventh pair of ribs, bounds its anterior wall below, while F, the pillars of the diaphragm, bound its posterior wall. The thoracic cavity is therefore considerably deeper in its posterior than in its anterior wall; and this occasions a difference of an opposite kind in the anterior and posterior walls of the abdomen; for while the abdomen ranges perpendicularly from E to W, its posterior range measures only from F to the ventra of the iliac bones, R. The arching form of the diaphragm, and the lower level which the pubic symphysis occupies compared with that of the cristae of the iliac bones, occasion this difference in the measure of both the thorax and abdomen.

The usual position of the kidneys, G G*, is on either side of the lumbar spine, between the last ribs and the cristae of the iliac bones. The kidneys lie on the fore part of the quadratus lumborum and psoae muscles. They are sometimes found to have descended as low as the iliac fossae, R, in consequence of pressure, occasioned by an enlarged liver on the right, or by an enlarged spleen on the left. The length of the abdominal part of the aorta may be estimated as being a third of the entire vessel, measured from the top of its arch to its point of bifurcation. So many and such large vessels arise from the abdominal part of the aorta, and these are set so closely to each other, that it must in all cases be very difficult to choose a proper locality whereat to apply a ligature on this region of the vessel. If other circumstances could fairly justify such an operation, the anatomist believes that the circulation might be maintained through the anastomosis of the internal mammary and intercostal arteries with the epigastric; the branches of the superior mesenteric with those of the inferior; and the branches of this latter with the perineal branches of the pubic. The lumbar, the gluteal, and the circumflex ilii arteries, also communicate around the hip-bone. The same vessels would serve to carryon the circulation if either L, the common iliac, V, the external iliac, or the internal iliac vessel, were the subject of the operation by ligature.

DESCRIPTION OF PLATE 25.

A. The arch of the aorta.

B B. The descending thoracic part of the aorta, giving off b b, the intercostal arteries.

C. The abdominal part of the aorta.

D D. First pair of ribs.

E. The xyphoid cartilage.

G G*. The right and left kidneys.

H. The brachio-cephalic artery.

I. Left common carotid artery.

K. Left subclavian artery.

L. Right common iliac artery at its place of division.

M. Left common iliac artery, seen through the meso-rectum.

N. Inferior vena cava.

O O. The sigmoid flexure of the colon.

P. The rectum.

Q. The urinary bladder.

R. The right iliac fossa.

S S. The right and left ureters.

T. The left common iliac vein, joining the right under the right common iliac artery to form the inferior vena cava.

U. Fifth lumbar vertebra.

V. The external iliac artery of right side.

W. The symphysis pubis.

X. An incision made over the locality of the femoral artery.

b b. The dorsal intercostal arteries.

c. The coeliac axis

d. The superior mesenteric artery.

f f. The renal arteries.

g. The inferior mesenteric artery.

h. The vas deferens bending over the epigastric artery and the os pubis, after having passed through the internal abdominal ring.



Plate 25



COMMENTARY ON PLATE 26.

THE RELATION OF THE INTERNAL PARTS TO THE EXTERNAL SURFACE OF THE BODY.

An exact acquaintance with the normal character of the external form, its natural prominences and depressions, produced by the projecting swell of muscles and points of bone, &c., is of great practical importance to the surgeon. These several marks described on the superficies he takes as certain guides to the precise locality and relations of the more deeply situated organs. And as, by dissection, Nature reveals to him the fact that she holds constant to these relations, so, at least, may all that department of practice which he bases upon this anatomical certainty be accounted as rooted in truth and governed by fixed principles. The same organ bears the same special and general relations in all bodies, not only of the human, but of all other species of vertebrata; and from this evidence we conclude that the same marks on surface indicate the exact situation of the same organs in all similar bodies.

The surface of the well-formed human body presents to our observation certain standard characters with which we compare all its abnormal conditions. Every region of the body exhibits fixed character proper to its surface. The neck, the axilla, the thorax, the abdomen, the groin, have each their special marks, by which we know them; and the eye, well versed in the characters proper to the healthy state of each, will soonest discover the nature of all effects of injury—such as dislocations, fractures, tumours of various kinds, &c. By our acquaintance with the perfect, we discover the imperfect; by a comparison with the geometrically true rectangled triangle, or circle, we estimate the error of these forms when they have become distorted; and in the same way, by a knowledge of what is the healthy normal standard of human form, we diagnose correctly its slightest degree of deformity, produced by any cause whatever, whether by sudden accident, or slowly-approaching disease.

Now, the abnormal conditions of the surface become at once apparent to our senses; but those diseased conditions which concern the internal organs require no ordinary exercise of judgment to discover them. The outward form masks the internal parts, and conceals from our direct view, like the covers of a closed volume, the marvellous history contained within. But still the superficies is so moulded upon the deeper situated structures, that we are induced to study it as a map, which discourses of all which it incloses in the healthy or the diseased state. Thus, the sternum points to A, the aorta; the middle of the clavicles, to C, the subclavian vessels; the localities 9, 10 of the coracoid processes indicate the place of the axillary vessels; the navel, P, points to Q, the bifurcation of the aorta; the pubic symphysis, Z, directs to the urinary bladder, Y. At the points 7, 8, may be felt the anterior superior spinous processes of the iliac bones, between which points and Z, the iliac vessels, V, 6, pass midway to the thigh, and give off the epigastric vessels, 2, 3, to the abdominal parietes. Between these points of general relations, which we trace on the surface of the trunk of the body, the anatomist includes the entire history of the special relations of the organs within contained. And not until he is capable of summing together the whole picture of anatomical analysis, and of viewing this in all its intricate relationary combination—even through and beneath the closed surface of living moving nature, is he prepared to estimate the conditions of disease, or interfere for its removal.

When fluid accumulates on either side of the thoracic compartment to such an excess that an opening is required to be made for its exit from the body, the operator, who is best acquainted with the relations of the parts in a state of health, is enabled to judge with most correctness in how far these parts, when in a state of disease, have swerved from these proper relations. In the normal state of the thoracic viscera, the left thoracic space, G A K N, is occupied by the heart and left lung. The space indicated within the points A N K, in the anterior region of the thorax, is occupied by the heart, which, however, is partially overlapped by the anterior edge of the lung, PLATE 22. If the thorax be deeply penetrated at any part of this region, the instrument will wound either the lung or the heart, according to the situation of the wound. But when fluid becomes effused in any considerable quantity within the pleural sac, it occupies space between the lung and the thoracic walls; and the fluid compresses the lung, or displaces the heart from the left side towards the right. This displacement may take place to such an extent, that the heart, instead of occupying the left thoracic angle, A K N, assumes the position of A K* N on the right side. Therefore, as the fluid, whatever be its quantity, intervenes between the thoracic walls, K K*, and the compressed lung, the operation of paracentesis thoracis should be performed at the point K, or between K and the latissimus dorsi muscle, so as to avoid any possibility of wounding the heart. The intercostal artery at K is not of any considerable size.

In the normal state of the thoracic organs, the pericardial envelope of the heart is at all times more or less uncovered by the anterior edge of the left lung, as seen in PLATE 22. When serous or other fluid accumulates to an excess in the pericardium, so as considerably to distend this sac, it must happen that a greater area of pericardial surface will be exposed and brought into immediate contact with the thoracic walls on the left side of the sternal median line, to the exclusion of the left lung, which now no longer interposes between the heart and the thorax. At this locality, therefore, a puncture may be made through the thoracic walls, directly into the distended pericardium, for the escape of its fluid contents, if such proceeding be in other respects deemed prudent and advisable.

The abdominal cavity being very frequently the seat of dropsical effusion, when this takes place to any great extent, despite the continued and free use of the medicinal diuretic and the hydragogue cathartic, the surgeon is required to make an opening with the instrumental hydragogue—viz., the trocar and cannula. The proper locality whereat the puncture is to be made so as to avoid any large bloodvessel or other important organ, is at the middle third of the median line, between P the umbilicus, and Z the symphysis pubis. The anatomist chooses this median line as the safest place in which to perform paracentesis abdominis, well knowing the situation of 2, 3, the epigastric vessels, and of Y, the urinary bladder.

All kinds of fluid occupying the cavities of the body gravitate towards the most depending part; and therefore, as in the sitting or standing posture, the fluid of ascites falls upon the line P Z, the propriety of giving the patient this position, and of choosing some point within the line P Z, for the place whereat to make the opening, becomes obvious. In the female, the ovary is frequently the seat of dropsical accumulation to such an extent as to distend the abdomen very considerably. Ovarian dropsy is distinguished from ascites by the particular form and situation of the swelling. In ascites, the abdominal swell is symmetrical, when the body stands or sits erect. In ovarian dropsy, the tumour is greatest on either side of the median line, according as the affected ovary happens to be the right or the left one.

The fluid of ascites and that of the ovarian dropsy affect the position of the abdominal viscera variously In ascites, the fluid gravitates to whichever side the body inclines, and it displaces the moveable viscera towards the opposite side. Therefore, to whichever side the abdominal fluid gravitates, we may expect to find it occupying space between the abdominal parietes and the small intestines. The ovarian tumour is, on the contrary, comparatively fixed to either side of the abdominal median line; and whether it be the right or left ovary that is affected, it permanently displaces the intestines on its own side; and the sac lies in contact with the neighbouring abdominal parietes; nor will the intestines and it change position according to the line of gravitation.

Now, though the above-mentioned circumstances be anatomically true respecting dropsical effusion within the general peritonaeal sac and that of the ovary, there are many urgent reasons for preferring to all other localities the line P Z, as the only proper one for puncturing the abdomen so as to give exit to the fluid. For though the peritonaeal ascites does, according to the position of the patient, gravitate to either side of the abdomen, and displace the moveable viscera on that side, we should recollect that some of these are bound fixedly to one place, and cannot be floated aside by the gravitating fluid. The liver is fixed to the right side, 11, by its suspensory ligaments. The spleen occupies the left side, 12. The caecum and the sigmoid flexure of the colon occupy, R R*, the right and left iliac regions. The colon ranges transversely across the abdomen, at P. The stomach lies transversely between the points, 11, 12. The kidneys, O, occupy the lumbar region. All these organs continue to hold their proper places, to whatever extent the dropsical effusion may take place, and notwithstanding the various inclinations of the body in this or that direction. On this account, therefore, we avoid performing the operation of paracentesis abdominis at any part except the median line, P Z; and as to this place, we prefer it to all others, for the following cogent reasons—viz., the absence of any large artery; the absence of any important viscus; the fact that the contained fluid gravitates in large quantity, and in immediate contact with the abdominal walls anteriorly, and interposes itself between these walls and the small intestines, which float free, and cannot approach the parietes of the abdomen nearer than the length which the mesenteric bond allows.

If the ovarian dropsy form a considerable tumour in the abdomen, it may be readily reached by the trocar and cannula penetrating the line P Z. And thus we avoid the situation of the epigastric vessels. The puncture through the linea alba should never be made below the point, midway between P and Z, lest we wound the urinary bladder, which, when distended, rises considerably above the pubic symphysis.

Amongst the many mechanical obstructions which, by impeding the circulation, give rise to dropsical effusion, are the following:—An aneurismal tumour of the aorta, A, or the innominate artery, [Footnote 1] F, may press upon the veins, H or D, and cause an oedematous swelling of the corresponding side of the face and the right arm. In the same way an aneurism of the aorta, Q, by pressing upon the inferior vena cava, T, may cause oedema of the lower limbs. Serum may accumulate in the pericardium, owing to an obstruction of the cardiac veins, caused by hypertrophy of the substance of the heart; and when from this cause the pericardium becomes much distended with fluid, the pressure of this upon the flaccid auricles and large venous trunks may give rise to general anasarca, to hydrothorax or ascites, either separate or co-existing. Tuberculous deposits in the lungs and scrofulous bronchial glands may cause obstructive pressure on the pulmonary veins, followed by effusion of either pus or serum into the pleural sac. [Footnote 2] An abscess or other tumour of the liver may, by pressing on the vena portae, cause serous effusion into the peritonaeal sac; or by pressure on the inferior vena cava, which is connected with the posterior thick border of the liver, may cause anasarca of the lower limbs. Matter accumulating habitually in the sigmoid flexure of the colon may cause a hydrocele, or a varicocele, by pressing on the spermatic veins of the left side. It is quite true that these two last-named affections appear more frequently on the left side than on the right; and it seems to me much more rational to attribute them to the above-mentioned circumstance than to the fact that the left spermatic veins open, at a disadvantageous right angle, into the left renal vein.