The Relation Of The Internal Parts To The External Surface Of The Body

Sources: Surgical Anatomy

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 hi 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.



[Footnote 1: The situation of this vessel, its close relation to the

pleura, the aorta, the large venous trunks, the vagus and phrenic

nerves, and the uncertainty as to its length, or as to whether or not a

thyroid or vertebral branch arises from it, are circumstances which

render the operation of tying the vessel in cases of aneurism very

doubtful as to a successful issue. The operation (so far as I know) has

hitherto failed. Anatomical relations, nearly similar to these, prevent,

in like manner, an easy access to the iliac arteries, and cause the

operator much anxiety as to the issue.]



[Footnote 2: The effusion of fluid into the pleural sac (from whatever

cause it may arise) sometimes takes place to a very remarkable extent. I

have had opportunities of examining patients, in whom the heart appeared

to be completely dislocated, from the left to the right side, owing to

the large collection of serous fluid in the left pleural sac. The

heart's pulsations could be felt distinctly under the right nipple.

Paracentesis thoracis was performed at the point indicated in PLATE 26.

In these cases, and another observed at the Hotel Dieu, the heart and

lung, in consequence of the extensive adhesions which they contracted in

their abnormal position, did not immediately resume their proper

situation when the fluid was withdrawn from the chest. Nor is it to be

expected that they should ever return to their normal character and

position, when the disease which caused their displacement has been of

long standing.]





DESCRIPTION OF PLATE 26.



A. The systemic aorta. Owing to the body being inclined forwards, the

root of the aorta appears to approach too near the lower boundary (N)

of the thorax.



B. The left brachio-cephalic vein.



C. Left subclavian vein.



D. Right brachia-cephalic vein.



E. Left common carotid artery.



F. Brachio-cephalic artery.



G G*. The first pair of ribs.



H. Superior vena cava.



I. Left bronchus.



K K*. Fourth pair of ribs.



L. Descending thoracic aorta.



M. Oesophagus.



N. Epigastrium.



O. Left kidney.



P. Umbilicus.



Q. Abdominal aorta, at its bifurcation.



R R*. Right and left iliac fossae.



S. Left common iliac vein.



T. Inferior vena cava.



U. Psoas muscle, supporting the right spermatic vessels.



V. Left external iliac artery crossed by the left ureter.



W. Right external iliac artery crossed by the right ureter.



X. The rectum.



Y. The urinary bladder, which being fully distended, and viewed from

above, gives it the appearance of being higher than usual above the

pubic symphysis.



Z. Pubic symphysis.



2. The left internal abdominal ring complicated with the epigastric

vessels, the vas deferens, and the spermatic vessels.



3. The right internal abdominal ring in connection with the like vessels

and duct as that of left side.



4. Superior mesenteric artery.



5, 6. Right and left external iliac veins.



7, 8. Situations of the anterior superior iliac spinous processes.



9, 10. Situations of the coracoid processes.



11, 12. Right and left hypochondriac regions.