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avoid the round ligament of the liver. If, in closing a median supra-umbilical laparotomy wound, the surgeon merely sutures the edges of the stretched lines alba without opening into the rectal sheaths, a hernia may result. To ensur against it the medial borders of the recti are exposed by opening into their th sheaths along each edge of the wound. In closing the wound, the deepes suture (continuous) includes on each side the posterior layer of the rectal sheath along with the split linea alba, the transversalis fascia and the peritoneum. This gives a substantial "first line of defence." The next suture takes up some of the fibres of the medial edges of the recti, along with the anterior layer of their sheathss The skin is sutured separately. By the above procedure the edges of the recti are brought into actual contact and a double-layered linea alba is fashioned, one layer are behind the margins of the recti and the other in front of them.
Below the umbilicus the medial edges of the recti are practically in contact, so that an incision between them opens into the rectal sheath on both sides.
The nearer the opening into the abdomen approaches the symphysis pubs the more likely is the bladder to be encountered; this applies more especially in children in whom the bladder extends higher up out of the pelvis. Before opening the abdomen, therefore, by a low median incision, the bladder should be emptied. in supra-pubic cystotomy, on the other hand, it is intentionally filled so as to elevate the peritoneum (superior false ligament of the bladder) well above the symphysis. Below this peritoneal layer is the space of Retzius, occupied by a pai of extra-peritoneal fat which must be separated by blunt dissection before the bladder wall is actually exposed. In opening the bladder the pre-vesical veins which ramify on its surface, are avoided as far as possible. Above the pubes the fascia transversalis recedes somewhat from the posterior surface of the recti, leaving behind it a cellular interval which must not be mistaken for the space of Retzius
If a transverse incision is added to the inferior end of a supra-umbilical median incision, free access may be obtained to the hypochondriac as well as to the ep gastric region. Before dividing the fibres of the rectus, however, the anter layer of the sheath is stitched to them to prevent their retraction. In dividing the posterior layer of its sheath the terminal portions of the ninth and tenth inter costal nerves need not be injured as they run in a transverse direction.
Incisions through the Recti. In opening the abdomen by longitudin incisions through the recti, the superior epigastric artery will be encountered above the umbilicus, and the inferior epigastric below it. The nearer the opening approaches the lateral border of the rectus, the more will its nerve-supply injured. Above the level of the umbilicus, the posterior layer of the rectal sheath well developed; and in closing the wound it is included in the same suture as the transversalis fascia and the peritoneum, the three together forming a most efficie "first line of defence." The higher up and further lateral the incision is mad through the rectus, the more will the posterior layer of the sheath be found to e made up of transverse muscular fibres prolonged inwards from the transvers abdominis muscle. Below the level of the umbilicus, the posterior layer of th rectal sheath is much thinner, and where it ceases, namely, about midway betwe the umbilicus and the pubes, it constitutes what is known as the linea semicircular (semilunar fold of Douglas). Below this level, therefore, the "deep closure" of laparotomy wound through the rectus is less secure than is the case at a high level. It is all the more important, therefore, to see that the edges of the anter layer of the sheath are accurately sutured.
Incisions Lateral to the Rectus.-Longitudinal incisions lateral and paral to the lateral border of the rectus are as far as possible to be avoided, first because they divide the motor nerves, and, secondly, because the abdominal wall almost entirely aponeurotic, and, therefore, a hernia is liable to result.
Incisions lateral to the rectus, above the level of the umbilicus, are general made more or less parallel to the costal margin. Such incisions give excelle: access to the gall-bladder and bile-ducts. The fibres of the external oblimuscles are divided transversely; but, fortunately, those of the internal oblyand transversus muscles may be divided more or less parallel to the fibres. T abdominal portions of the eighth, ninth, and tenth thoracic nerves which cours.
between the two deep muscles, run in a medial and slightly downward direction, so that it is practically impossible to avoid dividing one or other of them.
In the iliac regions, to reach the cæcum and vermiform process on the right side, and the pelvic colon on the left side (colostomy), it is customary, by using what is known as the "gridiron incision," to split the three abdominal muscles in the direction of their fibres. The external oblique is split in the direction of the skin incision, which is made obliquely from above downwards and medially. After retracting the edges of this muscle the fibres of the internal oblique and transversalis muscles are split horizontally. The abdomen is then opened by dividing the transversalis fascia and peritoneum. If a comparatively large opening is required the branch of the deep circumflex iliac artery, which ascends between the internal oblique and transversus muscles, a little medial to the anterior superior iliac spine, is divided and ligatured, while the ilio-hypogastric and ilio-inguinal nerves are to be avoided. If it is necessary to extend the incision in a medial direction, the lateral part of the anterior layer of the sheath of the rectus is opened and the rectus muscle retracted medially; while the inferior epigastric artery, now exposed, is pushed aside or ligatured before the opening in the fascia transversalis and peritoneum is enlarged.
DISTRIBUTION OF SENSORY NERVES IN ANTERIOR ABDOMINAL WALL.
A knowledge of the segmental distribution of the sensory fibres of the anterior rami of the lower intercostal nerves enables us to appreciate the significance of the so-called girdle pain often associated with lesions of the spinal medulla and its nerve-roots. In tuberculous disease of the vertebral column, for example, the girdle pain may be an early symptom of the disease, and when present it affords a valuable guide to the situation of the disease in the vertebral column. The seventh thoracic nerve supplies the skin at the level of the epigastric triangle, the eighth and ninth, that between it and the umbilicus, the tenth that at the level of the umbilicus, the eleventh and twelfth that between the umbilicus and groin.
THE ABDOMINAL CAVITY.
Subdivisions of the Abdominal Cavity.-To simplify the topography of the abdominal viscera the abdomen is arbitrarily divided into nine regions by two horizontal and two vertical planes. Of the two horizontal planes, the superior or infracostal plane is at the level of the lowest part of the tenth costal cartilages; the inferior or intertubercular plane is at the level of the tubercles of the iliac crests. The two vertical planes correspond upon the surface to a line, drawn vertically upwards on each side from a point midway between the anterior superior iliac spine and the pubic symphysis. Superiorly, these vertical planes generally strike the tip of the ninth costal cartilages. The subdivisions of the superior zone are termed the epigastric and right and left hypochondriac regions, of the middle zone the umbilical and right and left lumbar regions, of the inferior zone the hypogastric and right and left iliac regions. The epigastric, umbilical, and hypogastric regions may be further divided into right and left halves by the median plane. The xiphisternal junction is on a level with the fibro-cartilage between the ninth and tenth thoracic vertebræ. The infracostal plane passes through the superior part of the third lumbar vertebra; the intertubercular plane through the fifth lumbar vertebra, about one inch above the sacral promontory. The umbilicus is situated usually from one to two inches above the intertubercular line.
In the method of surface topography employed by Addison the plane of separation between the superior and middle abdominal zones is placed midway between the superior border of the manubrium sterni and the superior border of the pubic symphysis. It will be found to lie at or near the mid-point between the xiphisternal junction and the umbilicus. Posteriorly, this plane strikes the inferior border of the first lumbar vertebra, and it passes so constantly through the pylorus that it may with advantage be termed the transpyloric plane.
The peritoneal cavity may be regarded as a large and complicated lymph sac which is intimately related to the abdominal viscera, and more especially to the
gastro-intestinal canal. Inflammatory infections of the peritoneum are therefore almost always secondary to lesions of the viscera. The peritoneal lymph sac is brought into direct communication with the subperitoneal lymph vessels of the diaphragm through stomata which open upon the peritoneum covering the abdominal surface of that muscle. With the object, therefore, of diminishing septic absorption after operations for peritonitis, the patient is kept in the half-sitting posture, and pelvic drainage is established. The healthy peritoneum, in virtue of the vital action of its endothelial cells, is endowed with great absorptive properties, and, when irritated,
has the power of throwing out an abundant exudation, the cellelements of which are actively phagocytic.
FIG. 1102.-LATERAL ASPECT OF TRUNK, SHOWING SURFACE
R.L. Right lung.
R.K. Right kidney.
The reflection of the peritoneum and its relations to the various organs have been fully described in the section on the Digestive System.
The attachment of the transverse mesocolon to the posterior abdominal wall is at the level of the first lumbar vertebra, and lies, therefore, a little above the infracostal plane. The attachment, which ascends slightly as it passes from right to left, crosses the right kidney, the descending part of the duodenum, and the head of the pancreas, after which its attachment follows the anterior border of the pancreas. The peritoneal subdivision above this attachment is roofed in by the diaphragm, and includes the superior part of the great sac, and, behind it, the larger portion of the omental bursa. The organs related to this area of the peritoneum are the liver, along with the bile-ducts and gallbladder, the stomach and part of the duodenum, the spleen, the pancreas, the upper parts of the kidneys, and the suprarenal glands of Suppuration connected with any these organs is liable to spread upwards under the cupola of the diaphragm, producing what is known as subphrenic abscess.
The attachment of the mesentery of the small intestine extends from the left side of the second lumbar vertebra downwards to the right iliac fossa. The attachment may be mapped out on the surface by drawing a line from a point on the transpyloric line. one inch to the left of the median plane, to the mid-point of a line drawn horizontally between the right anterior superior iliac spine and the median plane.
Subdivisions of the Peritoneal Cavity. From the surgical point of view the peritoneal cavity may be arbitrarily divided into four great subdivisions: namely, a supracolic, a right infracolic, a left infracolic, and a pelvic. All these subdivisions communicate freely with one another behind the anterior abdominal wall, as well as on each side, along the gutter-like channels in the loins. It is along these gutters that pus readily makes its way from the upper part of
the abdomen along the lumbar regions into the iliac regions, and thence into the pelvis; and, on the other hand, the pus may ascend from the pelvis along the same channels, especially when the patient is in the recumbent posture.
The highest (subphrenic) region of the supracolic compartment is further sub-or divided into a right and left portion by the falciform ligament.
The omental bursa may be looked upon as a diverticulum of the first-mentioned the subdivision.
The subphrenic lymph plexus communicates, by means of lymph vessels which pierce the diaphragm, with the subpleural plexus on its superior surface: hence pus confined under tension in either of these spaces is liable to give rise to secondary infection of the corresponding pleural cavity. By adhesions of the transverse colon and greater omentum to the anterior abdominal wall, the supracolic subdivision of the peritoneal cavity may become more or less completely shut Liv off from the rest of the abdomen. Suppuration in the right half of the phrenicocolic subdivision is generally secondary to leakage from an ulcer of the first part of the duodenum or to disease of the gall-bladder and bile-ducts; while the left half of the space is more usually infected from the stomach. The best method of draining the supracolic subdivision of the peritoneal cavity is to pass a tube through the hepato-renal pouch of Morrison. The entrance to this pouch lies lateral to the gall-bladder between the inferior margin of the liver above and the right flexure of the colon below. The bottom of the pouch is formed by the reflection of the peritoneum from the superior part of the kidney on to the fascia transversalis covering the aponeurosis of origin of the transversus abdominis muscle below the tip of the twelfth rib. To drain it, a tube is introduced into it either from the wound in the anterior abdominal wall, or, still better, through a puncture opening made through the loin lateral to the kidney, in the angle between the twelfth rib and the lateral border of the sacro-spinalis muscle. Another drainage route is by a tube passed from the wound in the anterior abdominal wall into the omental bursa, through either the gastro-hepatic ligament or the great omentum.
The right infra-colic subdivision lies above and to the right of the mesentery of the small intestine. It is bounded, above, by the right and middle two-thirds of the transverse colon and the corresponding part of its mesentery, while laterally it is limited by the cæcum and ascending colon. At its right inferior angle are the ileo-cæcal junction and the vermiform process; at its right upper angle is the right flexure of the colon, while at its left upper angle is the inferior part of the duodenum, crossed by the superior mesenteric vessels.
The organs related to this subdivision are, in addition to the parts of the large intestine already mentioned, coils of small intestine, the inferior third of the right kidney, the right ureter, the inferior half of the descending and the horizontal part of the inferior portions of the duodenum.
Suppuration in connexion with the organs in this area involves more especially the right lumbar region, and may extend upwards along the colon into the subdiaphragmatic region, or downwards into the pelvis minor. To drain this region. a tube is introduced into the right lumbar region either through the anterior abdominal wall or through a stab-wound in the loin lateral to the ascending colon.
The left infra-colic subdivision, which lies below and to the left of the mesentery, narrows as it passes upwards and reaches to a higher level than the right infra-coli subdivision. Inferiorly, it is directly continuous at the superior aperture of the pelvis with the peritoneal cavity of the pelvis minor. Above, it is bounded by the left third of the transverse colon and its mesentery, and, still more posteriorly, by the inferior surface of the body of the pancreas; laterally it is bounded by the descending and iliac portions of the colon. At its right upper angle is the duodenojejunal flexure, lying immediately to the left of the vertebral column, in the angle between it and the inferior surface of the pancreas. At its left superior angle is the left flexure of the colon, while at its left inferior angle is the junction iliac with pelvic colon. This subdivision of the peritoneal cavity, in addition to containing the majority of the coils of the small intestine, is related to the inferior third of the left kidney, the left ureter, the lower part of the abdominal aorta and vena cava, and the inferior mesenteric and common iliac vessels. Drainage of this