Part 3

=Apex of the heart.=--The apex of the heart pulsates between the fifth and sixth ribs, two inches below the nipple, and one inch to its sternal side. The place and extent, however, of the heart’s impulse, vary a little with the position of the body. Of this anyone may convince himself by leaning forwards, backwards, on this side and on that, feeling, at the same time, the heart. Inspiration and expiration also alter the position of the heart. In a deep inspiration it may descend half an inch, and can be felt beating at the pit of the stomach.

43. =Valves of the heart.=--The aortic valves lie behind the third intercostal space, close to the left side of the sternum.

The pulmonary valves lie in front of the aortic behind the junction of the third costal cartilage, on the left side, with the sternum.

The tricuspid valves lie behind the middle of the sternum, about the level of the fourth costal cartilage.

The mitral valves (the deepest of all) lie behind the third intercostal space, about one inch to the left of the sternum.

Thus these valves are so situated that the mouth of an ordinary sized stethoscope will cover a portion of them all, if placed over the sternal end of the third intercostal space, on the left side. All are covered by a thin layer of lung; therefore we hear their action better when the breathing is for a moment suspended.

44. =Outline of the lungs.=--Now let us trace on the chest the outline of the lungs, with as much precision as their expansion and contraction in breathing permit. (See the cut.)

45. The apex of each lung rises into the neck behind the sternal end of the clavicle and sterno-mastoid muscle as much as an inch and a half: in females rather higher than in males (30). From the sternal ends of the clavicles the lungs converge, so that their thin edges almost meet in the mesial line on a level with the second costal cartilage. Thus there is little or no lung behind the first bone of the sternum. From the level of the second costal cartilage to the level of the fourth, the margins of the lungs run parallel, or nearly so, close behind the middle of the sternum: consequently their thin edges overlap the great vessels and valves at the base of the heart.

Below the level of the fourth costal cartilage the margins of the lungs diverge, but not in an equal degree. The margin of the right corresponds with the direction of the cartilage of the sixth rib: the margin of the left, being notched for the heart, runs behind the cartilage of the fourth. A line drawn perpendicularly from the nipple would find the lung margin about the lowest part of the sixth rib. Laterally, _i.e._ in the axillary line, the lung margin comes down as low as the eighth rib: posteriorly, _i.e._ in the dorsal or scapular line, it descends as low as the tenth.

It should be remembered that, in a deep inspiration, the lung margins descend about one inch and a half.

In children the lungs are separated in front by the thymus gland. Allowance should be made for this. About the approach of puberty the thymus disappears.

46. =Anterior mediastinum.=--The direction of the anterior mediastinum is not straight down the middle of the sternum, but slants a little to the left, owing to the position of the heart. The right pleural sac generally encroaches a little upon the left, behind the middle of the sternum. A needle introduced through the middle of the sternum opposite the third or the fourth rib would go through the right pleura.

47. =Reflection of pleura.=--The reflection of the pleura from the wall of the chest on to the diaphragm corresponds with a sloping line drawn from the bottom of the sternum over the cartilages of the ribs down to the lower border of the last rib.

Since the pleura lines the inside of the last rib, a musket ball or other foreign body, loose in the pleural sac, and rolling on the diaphragm, might fall to the lowest part of the sac, which would be between the eleventh and twelfth ribs. The ball might be extracted here. The chest might also be tapped here, but not with a trochar, since a trochar would penetrate both layers of pleura, and go through the diaphragm into the abdomen.

The operation should be done cautiously, by an incision beginning about two inches from the spine, on the outer border of the ‘erector spinæ,’ on a level between the spines of the eleventh and twelfth dorsal vertebræ. The intercostal artery will not be injured if the opening be made below the middle of the space, which is very wide.[3]

_THE BACK._

48. =Median furrow.=--In a muscular man, a furrow, caused by the prominence of the erector spinæ on each side, runs down the middle of the back. The lower end of the furrow corresponds with the interval between the spine of the last lumbar and that of the first sacral vertebra.

49. =Spines of vertebræ.=--A little friction with the fingers down the backbone will cause the spines of the vertebræ to be tipped with red, so that they can be easily counted, and any deviation from the straight line detected. Still it is worth remembering that the spine of the third dorsal is on a level with the commencement of the spine of the scapula--that the spine of the seventh dorsal is on a level with the inferior angle of the scapula--that the spine of the last dorsal is on a level with the head of the last rib.

=Division of the trachea.=--The division of the trachea is opposite the spine of the third, in some cases the fourth, dorsal vertebra. In front this division is on the level of the junction of the first with the second bone of the sternum.

The root of the spine of the scapula is marked by a slight dimple in the skin. This is on a level with the third intercostal space. A stethoscope placed on the inner side of this dimple would cover the bronchus, more especially the right, since it is nearer to the chest wall.

Make a man lean forwards, with his arms folded across the chest; this will make prominent the spines of the vertebræ. The lower border of the trapezius will guide you to the spine of the twelfth dorsal vertebra.

50. The place where the kidney is most accessible to pressure is below the last rib, on the outer edge of the erector spinæ.

51. The highest part of the ilium is about the level of the fourth lumbar spine. The best incision for opening the descending colon is in a slightly sloping line beginning at the outer edge of the erector spinæ, midway between the crest of the ilium and the last rib, and continued across the flank for three inches or more, according to the amount of subcutaneous fat.

52. In the pit of the neck we can feel the trapezius and the ligamentum nuchæ. By pressing deeply we detect the forked and prominent spine of the second cervical vertebra.

53. The spines of the third, fourth, and fifth cervical vertebræ recede from the surface to permit free extension of the neck, and cannot often be felt. But the spines of the sixth and seventh (v. prominens) stand out well.

54. Notice that most of the spines of the dorsal vertebræ, owing to their obliquity, do not tally with the heads of their corresponding ribs. Thus, the spine of the second dorsal corresponds with the head of the third rib; the spine of the third dorsal with the head of the fourth rib, and so on till we come to the eleventh and twelfth dorsal vertebræ, which do tally with their corresponding ribs. All this, however, is best seen in the skeleton.

55. The spines of the vertebræ may be useful as landmarks indicative of the levels of important organs. I have therefore arranged them in a tabular form, thus:--

TABULAR PLAN OF PARTS OPPOSITE THE SPINES OF THE VERTEBRÆ.

{ 5th. Cricoid cartilage. Œsophagus begins. CERVICAL. { 7th. Apex of lung: higher in the female than in the { male. (30)

{ 1st. { 2nd. { 3rd. Aorta reaches spine. Apex of lower lobe of lung. { Angle of bifurcation of trachea. (49) { 4th. Aortic arch ends. Upper level of heart. { 5th. { 6th. DORSAL. { 7th. { 8th. Lower level of heart. Central tendon of diaphragm. { 9th. Œsophagus and vena cava through diaphragm. Upper edge of spleen. { 10th. Lower edge of lung. Liver comes to surface posteriorly. Cardiac orifice of stomach. { 11th. Lower border of spleen. Renal capsule. { 12th. Lowest part of pleura. Aorta through diaphragm. Pylorus.

{ 1st. Renal arteries. Pelvis of kidney. (83) { 2nd. Termination of spinal cord. Pancreas. Duodenum just below. Receptaculum chyli. LUMBAR. { 3rd. Umbilicus. Lower border of kidney. { 4th. Division of aorta. (65) Highest part of ilium. { 5th.

56. =Origins of the spinal nerves.=--It is useful to know opposite what vertebræ the spinal nerves in the different regions arise from the spinal cord. They arise as follows:--

The origins of the eight cervical nerves correspond to the interval between the occiput and the sixth cervical spine.

The origins of the first six dorsal nerves correspond to the interval between the sixth cervical and the fourth dorsal spines.

The origins of the six lower dorsal nerves correspond to the interval between the fourth and the eleventh dorsal spines.

The origins of the five lumbar nerves correspond to the interval between the eleventh and twelfth dorsal spines.

The origins of the five sacral nerves correspond to the spines of the last dorsal and the first lumbar vertebræ.

57. =Movements of the spine.=--The movements of which the spine is capable are threefold: 1. Flexion and extension; 2. Lateral inclination; 3. Torsion. Flexion and extension are freest between the third and the sixth cervical vertebræ, between the eleventh dorsal and the second lumbar, and between the last lumbar and the sacrum. This is well marked in severe cases of opisthotonos, where the body is supported on the back of the head and heels.[4]

Still better may it be observed when a mountebank bends backwards, and touches the ground with his head.

The lateral movement is freest in the neck and the loins.

The movement of torsion or rotation round its own axis may be proved by the following experiment:--Seated upright, with the back and shoulders well applied against the back of a chair, we can turn the head and neck as far as 70°. Leaning forwards so as to let the dorsal and lumbar vertebræ come into play, we can turn 30° more.

58. =Position and motions of scapula.=--There are a few points worthy of observation about the scapula. It covers the ribs from the second to the seventh inclusive. We can feel its superior angle covered by the trapezius. The inferior angle is covered by the latissimus dorsi, which keeps it well applied against the ribs in the strong and athletic; but in weak and consumptive persons the lower angles of the scapulæ project like wings--hence the term ‘scapulæ alatæ.’

A line drawn horizontally from the spine of the sixth dorsal vertebra over the inferior angle of the scapula gives the upper border of the latissimus dorsi. Another line drawn from the root of the spine of the scapula to the spine of the last dorsal vertebra gives the lower border of the trapezius, which stands a little in relief.

59. The sliding movement of the scapula on the chest can be properly understood only on the living subject. It can move not only upwards and downwards as in shrugging the shoulders--backwards and forwards as in throwing back the shoulders--but it has a rotatory movement round a movable centre. This rotation is seen while the arm is being raised from the horizontal to the vertical position, and is effected by the co-operation of the trapezius with the serratus magnus. The glenoid cavity is thus made to look upwards, the inferior angle slides forwards, and is well held under the latissimus dorsi.

60. For the medical examination of the back, the patient should sit with the arms hanging between his thighs, to lower the scapulæ as much as possible. In this position the spine of the scapula corresponds (nearly) with the fissure between the upper and lower lobes of the lung; the apex of the lower lobe being about the level of the third rib.

_THE ABDOMEN._

The student is assumed to be familiar with the conventional lines dividing the abdomen into regions.

61. =Abdominal lines.=--The linea alba, or central line of the abdomen, marks the union of the aponeuroses of the abdominal muscles. It runs from the apex of the ensiform cartilage to the symphysis pubis. As this line is the thinnest and least vascular part of the abdominal wall, we make our incision along it in ovariotomy, and in the high operation of lithotomy; in it, we tap the abdomen in ascites, and the distended bladder in retention of urine.

The so-called ‘linea semilunaris,’ at the outer border of the sheath of the rectus, corresponds with a line, drawn slightly curved (with the concavity towards the linea alba), from the lowest part of the seventh rib to the spine of the pubes. This line would be in an adult about three inches from the umbilicus; but in an abdomen distended by dropsy or other cause, the distance is increased in proportion.

It is important to know the position of the ‘lineæ transversæ,’ or tendinous intersections across the rectus abdominis. There are rarely any below the umbilicus, and generally three above it. The first is about the level of the umbilicus. The second is about four inches higher--that is, about the level of the lowest part of the tenth rib. These are the principal lines, and they divide the upper part of each rectus into two nearly quadrilateral portions, an upper and a lower: of these, those on the right side are a trifle larger than on the left. We see these muscular squares pretty plainly in some athletic subjects. Much more frequently we see them, too much exaggerated, on canvas and in marble. Artists are apt to exaggerate them, and make the front of the belly too much like a chess-board. It is lucky for them that all the world do not see with anatomical eyes.

A familiarity with the shape and position of these divisions of the rectus is of importance, lest we should, in ignorance, make a mistake in our diagnosis. A spasmodic contraction of one of these divisions, particularly the upper, or a collection of matter within its sheath, has been frequently mistaken for deep-seated abdominal disease.

In the erect position, the anterior superior spines of the ilia are a little below the level of the promontory of the sacrum. The bifurcation of the aorta is on about the level of the highest part of the crest of the ilium.

62. =Umbilicus.=--The umbilicus is not midway between the ensiform cartilage and the pubes, but rather nearer to the pubes. In all cases it is situated above the centre of a man’s height. It is a vulgar error to say that when a man lies with legs and arms outstretched, and a circle is drawn round him, the umbilicus lies in the centre of it. This central point is in most persons just above the pubes.

In very corpulent persons two deep transverse furrows run across the abdomen. One runs across the navel and completely conceals it. The other is lower down, just above the fat of the pubes. In tapping the bladder above the pubes in such a case, the trochar should be introduced where this line intersects the linea alba.

Although the position of the umbilicus varies a little in different persons, as the abdomen is unusually protuberant or the reverse, still, as a general rule, it is placed about the level of the body of the third lumbar vertebra. Now, since the aorta divides a little below the middle of the fourth lumbar, it follows that the best place to apply pressure on this great vessel is one inch below the umbilicus, and slightly to the left of it (65). That the aorta can, under favourable circumstances, be compressed under chloroform sufficiently to cure an aneurysm below it, is proved by recorded cases, and by none more effectually than by a case related in the second volume of the ‘Reports of St. Bartholomew’s Hospital.’

It may be asked, why not apply pressure on the aorta above the umbilicus? The answer is, that the aorta above the umbilicus is farther from the surface, and is, moreover, covered by important structures upon which pressure would be dangerous.

63. =Parts behind linea alba.=--Let us next consider what viscera lie immediately behind the linea alba. For two or three fingers’ breadth below the ensiform cartilage there is the left lobe of the liver, which here crosses the middle line. Below the edge of the liver comes the stomach, more or less in contact with the linea alba, according to its degree of distension. In extreme distension the stomach pushes everything out of the way, and occupies all the room between the liver and the umbilicus. When empty and contracted, it retreats behind the liver, and lies flat in front of the pancreas at the back of the abdomen; thus giving rise to the hollow termed the ‘pit of the stomach.’ But as the stomach distends, it makes a considerable fulness where there was a pit. The middle of the transverse colon lies above the umbilicus, occupying space (vertically two or three inches) according to its distension. Behind and below the umbilicus, supposing the bladder contracted, are the small intestines, covered by the great omentum.

64. =Peritoneum.=--The peritoneum is in contact with the linea alba all the way down to the pubes, when the bladder is empty. But when the bladder distends, it raises the peritoneum from the middle line above the pubes; so that with a bladder distended half-way up to the umbilicus, there is a space of nearly two inches above the symphysis where the bladder may be tapped without risk of injury to the peritoneum. For the same reason, we have space sufficient for the successful performance of the high operation for stone. This fact in anatomy must have been well understood by Jean de Dot, the smith at Amsterdam, who, in the seventeenth century, cut himself in the linea alba above the pubes, and took out of his bladder a stone as large as a hen’s egg. The stone, the knife, and the portrait of the operator, may be seen to this day in the museum at Leyden.

65. =Division of Aorta.=--The aorta generally divides at a point one inch and a half below the umbilicus. A more reliable guide to this division than the umbilicus, is a point (a very little to the left) of the middle line about the level of the highest part of the crest of the ilium. A line drawn with a slight curve outwards from this point to the groin, where the pulsation of the common femoral can be distinctly felt (rather nearer to the pubes than the ilium), gives the direction of the common iliac and external iliac arteries. About the first two inches of this line belong to the common iliac, the remainder to the external. Slight pressure readily detects the pulsation of the external iliac above ‘Poupart’s ligament.’

As a rule, the length of the common iliac is about two inches, but it should be remembered there are frequent deviations. It may be between three-quarters of an inch and three inches and a half long. These varieties may arise either from a high division of the aorta, or a low division of the common iliac, or both. It is impossible to ascertain during life what is its length in a given instance, for there is no necessary relation between its length and the height of the stature. It is often short in tall men, and _vice versâ_. Anatomists generally describe the right as a trifle longer than the left; but their average length is pretty nearly the same.

66. Mr. Abernethy, who in the year 1796 first put a ligature round the external iliac, made his incision in the line of the artery. But the easiest and safest way to reach the vessel is by an incision (recommended in the first instance by Sir Astley Cooper, and now generally adopted), beginning just on the inner side of the artery, a little above Poupart’s ligament, and continued upwards and outwards a little beyond the spine of the ilium. The same incision extended farther in the same direction would reach the common iliac.

67. =Bony prominences.=--The anterior superior spine of the ilium, the spine of the pubes, and the line of Poupart’s ligament, are landmarks with which every surgeon should be thoroughly familiar.

68. =Spine of ilium.=--The spine of the ilium is the spot from which we measure the length of the lower extremity. It is a valuable landmark in determining the nature of injuries to the pelvis and the hip. The thumb easily feels the spine, even in fat persons. Its position with regard to the trochanter major should be carefully examined. The best way to do this is to place the thumbs firmly on the opposite spines, and to grasp the trochanters with the fingers. Any abnormal position on one side is thus easily ascertained with the sound side as a guide.

69. =Spine of pubes.=--The spine of the pubes is the best guide to the external abdominal ring. It cannot easily be felt by placing the finger directly over it, since it is generally covered by fat. To feel it distinctly, we should push up the skin of the scrotum and get beneath the subcutaneous fat. If there be any difficulty in finding it, abduct the thigh, and the tense tendon of the adductor longus will lead up to it.

The position of the spine of the pubes is appealed to as a means of diagnosis in doubt between inguinal and femoral hernia. The spine lies on the outer side of the neck of an inguinal hernia, on the inner side of the neck of a femoral.

The spine of the pubes is nearly on the same horizontal line as the upper part of the trochanter major. In this line, about one full inch external to the spine, is the femoral ring. Here is the seat of stricture in a femoral hernia.

70. =Poupart’s ligament, or crural arch.=--The line of Poupart’s ligament (crural arch) is in most persons indicated by a slight crescent-like furrow along the skin. It corresponds with a line drawn not straight, but with a gentle curve downwards from the spine of the ilium to the spine of the pubes. With the help of the preceding landmarks it is easy to find the exact position of the external and internal abdominal rings, and the direction of the inguinal canal.

71. =Abdominal rings.=--The external abdominal ring is situated immediately above the spine of the pubes. It is an oval opening with the long axis directed obliquely downwards and inwards. Though its size varies a little in different persons, yet as a rule it will admit the end of the little finger, so that we can tell by examination whether it be free or otherwise. To ascertain this, the best way is to push up the thin skin of the scrotum before the finger; then, by tracking the spermatic cord, the finger readily glides over the crest of the pubes and feels the sharp margins of the ring.

The position of the internal ring is about midway between the spine of the ilium and the symphysis of the pubes, and about two-thirds of an inch above Poupart’s ligament.

72. =Inguinal canal.=--The position of the external and internal abdominal rings being ascertained, it is plain that the direction of the inguinal canal must be obliquely downwards and inwards, and that its length in a well-formed adult male is from one and a half to two inches, according as we include the openings or not. In very young children the canal is much shorter and less oblique, the inner ring being behind the outer. With the growth of the pelvis in its transverse direction, the anterior spines of the ilia become farther apart, and thus draw the internal ring more and more away from (_i.e._ to the outer side of) the external.

73. =Spermatic cord.=--The spermatic cord can be felt as it emerges through the external ring, and its course can be tracked into the scrotum. The vas deferens can be distinctly felt at the back of the cord, and separated from its other component parts.