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The upper part of the ureter is exposed by extending the division of the abdominal muscles still further downwards and forwards into the iliac region. After stripping the peritoneum off the quadratus and psoas muscles, the ureter will be found to cling to the deep surface of the membrane. Care is taken not to injure the internal spermatic or ovarian vessels, which cross the ureter superficially, and from the medial to the lateral side. The ureter is surrounded by a quantity of loose cellular tissue, and, owing to an abundance of elastic fibres in its adventitious coat, is very elastic, so that it can be readily pulled up to the surface. To deliver an enlarged kidney out of the loin, it is generally necessary to prolong the incision upwards so as to divide the lateral lumbo-costal arch; and it may be necessary to divide, fracture, or resect the twelfth rib also. In doing this it is not always possible to avoid opening into the lowest part of the pleural sinus, which descends in front of the medial half of the rib.
In operating on the kidney, the last thoracic, and the ilio-hypogastric and ilio-inguinal nerves, which lie between it and the quadratus lumborum, must not be injured; the last thoracic nerve should be retracted upwards and laterally, the other two downwards and medially.
A needle passed through the medial extremity of the eleventh intercostal space will transfix the suprarenal gland.
The pus of a perinephric abscess occupies the fatty layer of the tela subserosa (perinephric fat), and lies, therefore, within the fascial envelope of the abdomen; the pus in a psoas abscess, on the other hand, lies external to the fascia. opening a psoas abscess from behind, a vertical incision is made in the angle formed by the lateral border of the sacrospinalis and the crest of the ilium; in the deeper part of the dissection the surgeon should keep close to the front of the transverse process of the fourth lumbar vertebra.
Diaphragm, Liver, Stomach, and Large Intestine.-Posteriorly the right arch of the diaphragm and the right lobe of the liver extend upwards to the level of the angle of the scapula (eighth rib), while the left arch and the fundus of the stomach lie one inch lower (eighth interspace); the central tendon reaches up to the eighth thoracic spine. The right lobe of the liver is covered posteriorly by the eighth to the twelfth ribs, and is overlapped by the base of the right lung as far as a line drawn horizontally laterally from the tenth thoracic spine; hence, posteriorly, the superior limit of the liver cannot be defined by percussion, and its inferior limit merges into the dulness of the loin muscles and kidney.
The cardiac orifice of the stomach lies one inch to the left of the ninth thoracic spine. The cardiac portion, overlapped by the ninth to the twelfth ribs, extends upwards to the level of the eighth thoracic spine, one inch below the inferior angle of the scapula. The pyloric portion crosses the median plane opposite the first and second lumbar spines, the pylorus itself being situated one inch to the right of the first lumbar spine. The lesser curvature lies to the left of and below the tenth, eleventh, and twelfth thoracic spines.
Viewed from behind, the large intestine, on both sides, overlaps the lateral border of the kidneys and lies parallel to the lateral border of the sacrospinalis muscles. The peritoneum is reflected from the colon on to the posterior abdominal wall along a line drawn vertically upwards from the centre of the iliac crest. The left flexure of the colon, which reaches up to the level of the twelfth thoracic spine and the tenth rib, lies about five inches above the iliac crest. The right flexure lies on a level with the first lumbar spine.
Spleen. The spleen, situated in the left hypochondrium, behind the cardiac end of the stomach, is overlapped by the ninth, tenth, and eleventh ribs, the long axis of the organ corresponding approximately to that of the tenth rib. Between the superior third of the spleen and the chest wall (pleura and diaphragm intervening) is the base of the left lung, the inferior margin of which crosses the organ horizontally at the level of the tenth thoracic spine. The costo-diaphragmatic reflection of the pleura reaches down as far as the inferior angle of the spleen. The superior limit of the organ cannot therefore be defined by percussion; and unless enlarged, or displaced downwards, the spleen cannot be punctured from behind without traversing the pleural as well as the peritoneal cavity.
Of the three angles of the spleen, the posterior or vertebral lies at the same level as the inferior margin of the lung, 1 in. lateral to the tenth thoracic spine. The
FIG. 1110.-POSTERIOR ASPECT OF TRUNK, SHOWING SURFACE TOPOGRAPHY OF VISCERA.
inferior angle lies opposite the eleventh intercostal space on a level with the first lumbar spine, in a line drawn vertically upwards from a point one inch behind the
centre of the iliac crest. This angle is situated behind the superior part of the descending colon, immediately lateral to the middle of the lateral border of the kidney. The anterior angle is at the level of the ninth interspace in the midaxillary line. Having placed a mark on the skin opposite these three angles the organ is mapped out on the surface as follows:-The posterior margin is obtained by joining the posterior and inferior angles; this margin, which gives the key to the position of the spleen, will be found to follow the tenth intercostal space. The short inferior margin corresponds to a line joining the anterior and the
FIG. 1111.-DISSECTION OF THE LEFT HYPOCHONDRIUM TO SHOW THE RELATIONS OF THE SPLEEN TO THE SIDE WALL OF THE CHEST, THE DIAPHRAGM, AND THE ADJACENT VISCERA. In addition to the portions of ribs, there has been removed a part of the base of the left lung, and a window has been made in the diaphragm almost down to the level of the costo-diaphragmatic reflection of the pleura.
inferior angles; it is related to the left flexure of the colon. Commencing at the vertebral angle, the anterior margin is at first arched, the summit of the arch reaching to the level of the upper border of the ninth rib in the scapular line; thence it is continued downwards and forwards across the posterior axillary line as the "anterior crenated border" to the anterior angle. The upper arched portion lies parallel to and about one inch below the highest part of the fundus of the stomach. The only parts of the splenic outline which can be defined by percussion are the lower crenated part of the anterior margin, the anterior angle, and the short postero-inferior or colic border; and it is these parts which may be felt below the costal margin when the organ is considerably enlarged.
In excising the spleen it is important to remember that the splenic vessels lie between the two layers of the lieno-renal ligament, and not in the gastro-lienal ligament, which contains the short gastric vessels. In a floating spleen these two peritoneal ligaments are elongated to form a distinct pedicle.
Pancreas.-The head of the pancreas lies opposite the last thoracic and first lumbar spines; the tail lies at the same level as the left flexure of the colon, a little above the inferior basal angle of the spleen.
TABLE INDICATING THE LEVEL OF THE MORE IMPORTANT STRUCTURES IN
Superior limit of heart.
Centre of root of lung.
Inferior angle of scapula.
Orifice of inferior vena cava.
Upper end of lumbar enlargement.
Lower limit of pleura at vertebral column
Body of pancreas.
Lesser curvature of stomach.
Level at which pleura crosses twelfth rib.
Left flexure of colon.
Superior part of head of pancreas.
Pylorus and pyloric portion of stomach.
TABLE INDICATING THE LEVEL OF THE MORE IMPORTANT STRUCTURES IN
Spinal Medulla.-The spinal medulla ends opposite the inferior border of the first lumbar spine; in the infant it reaches to the interval between the second and third lumbar spines. The cervical enlargement, which corresponds to the lower four cervical and the first two thoracic segments, ends opposite the seventh cervical spine. The lumbar enlargement lies opposite the last three thoracic spines. The five lumbar segments are opposite the ninth, tenth, and eleventh thoracic spines, while the five sacral segments extend from the lower border of the eleventh thoracic to the lower border of the first lumbar spine.
The sub-dural space extends down to the level of the second sacral spine. In performing the operation of lumbar puncture (Quincke) a fine trochar and cannula are introduced into the sub-arachnoid space below the level of the spinal medulla, the puncture being made to in. to one side of the interspinous ligament in the interval between the third and fourth or fourth and fifth lumbar spines. instrument should be directed medially towards the median plane and very slightly upwards. In the adult the distance of the dura mater from the surface is about 2 in., in the infant in.
Fracture-dislocations of the vertebral column are commonest in the lower cervical and thoracico-lumbar regions; that is to say, where the movable cervical and lumbar regions join the more fixed thoracic region. The vertebral column above the injury is generally displaced forwards, so that the spinal medulla is often severely lacerated or completely torn across by the superior end of the portion of the column below the fracture. It is important to remember that in consequence of the shortness of the spinal medulla as compared with the vertebral column, the origins of the spinal nerves are at a higher level than their exits from the vertebral canal. The distance between origins from the spinal medulla and exits through the intervertebral foramina becomes greater the further down the nerves are, the lowest nerve trunks running almost vertically downwards. The cervical nerves leave the vertebral canal above the vertebræ after which they are named (except the eighth, which is above the first thoracic vertebra); the thoracic, lumbar, and sacral nerves, on the other hand, leave the canal below the correspondingly named