Handa 9781496386441 Full Sample Chap 1

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SECTION I  Preparing for Surgery

I used. For example, low transverse fascial incisions often used for gynecologic surgery should not extend beyond lateral margins of rectus muscles to avoid nerve and inferior epigastric vessel injury. In addition, suture pur- chases that extend lateral to the edges of incision should be avoided as they may entrap the iliohypogastric and/ or ilioinguinal nerve, which may lead to denervation injury or pain as described later (under ilioinguinal and iliohypogastric sections below). Many specialized aspects of the rectus sheath are impor- tant to the surgeon ( FIG. 1.4 ). In its lower one fourth, the sheath lies entirely anterior to the rectus muscle. Above that point, it splits to lie both anterior and posterior to the rectus muscle, thus forming the anterior and posterior layers of the rectus sheath. The transition between these two arrangements occurs at the arcuate line, approxi- mately one third of the distance from the umbilicus to the pubic crest, which lies medial to the pubic tubercle. Superior to this line, the midline ridge of the rectus sheath, the linea alba, unites the anterior and posterior layers of the sheath. Sharp dissection is usually required to separate these layers in the midline during a Pfannenstiel incision. Below the arcuate line, the rectus abdominis muscles are in contact with the transversalis fascia. A vertical incision that extends to or above the umbilicus therefore requires incision of the posterior sheath. The lateral border of the rectus muscle is marked by the linea semilunaris, a curved tendinous line that extends from the cartilage of the ninth rib to the pubic tubercle. It is formed by the internal oblique aponeu- rosis at its line of division to enclose the rectus mus- cle and is reinforced anteriorly by the external oblique and transversus abdominis aponeurosis. The linea semilunaris is not always where the three layers of flank muscles fuse: above the arcuate line, the inter- nal oblique muscle aponeurosis splits to contribute to the anterior and posterior layers of the rectus sheath, while below the arcuate line, the transversalis fascia lies immediately posterior to the rectus muscles. During a transverse lower abdominal incision, the external and internal oblique aponeuroses are often separable near the midline. A hernia through the linea semilunaris is called a Spigelian hernia or lateral–ventral hernia. The inguinal canal lies at the lower edge of the mus- culofascial layer of the abdominal wall. It is superior and parallel to the inguinal ligament. The midinguinal point is halfway between the pubic symphysis and the anterosuperior iliac spine. The femoral pulse can be palpated here. The inguinal canal has two openings, the superficial and deep inguinal rings. In the embryological stage, the canal is lined by an outpocketing of the peri- toneum (processus vaginalis) and the abdominal mus- culature. Failure of the processus vaginalis to regress can lead to an indirect inguinal hernia, where the peri- toneal sac or potentially loops of bowel enter the ingui- nal canal through the deep inguinal ring, lateral to the inferior epigastric vessels. Through the inguinal canal,

in the woman, the round ligament extends to its termi- nation in the labium majus. In addition, the ilioinguinal nerve and the genital branch of the genitofemoral nerve pass through the canal. Transversalis Fascia, Peritoneum, and Bladder Reflection Deep to the muscular layers and superficial to the peri- toneum lies the transversalis fascia, a layer of fibrous tissue that lines the abdominopelvic cavity. It is visible during abdominal incisions as the layer just underneath the rectus abdominis muscles suprapubically ( FIG. 1.2 ). It is separated from the peritoneum by a variable layer of extraperitoneal adipose tissue, sometimes called the preperitoneal fat. The transversalis fascia is frequently incised or bluntly dissected off the bladder to take the tissues in this region “down by layers.” This is the layer of tissue that is last penetrated to gain extraperitoneal entry into the retropubic space. The peritoneum is a single layer of epithelial cells and supporting connective tissue called the serosa that lines the abdominal cavity and covers the abdominopelvic organs. The infraumbilical part of the anterolateral abdominal wall is characterized by five peritoneal folds ( FIG. 1.5 ) that converge toward the umbilicus. The sin- gle median umbilical fold extends from the apex of the bladder to the umbilicus and covers the median umbili- cal ligament, a fibrous remnant of the urachus. Lateral to this are paired medial umbilical folds, which cover the medial umbilical ligaments, formed by the occluded part of the umbilical arteries. The lateral umbilical folds cover the inferior epigastric arteries and veins and, if transected, can lead to significant bleeding. The reflection of the bladder onto the abdominal wall is triangular in shape, with its apex blending into the median umbilical ligament. Because the apex is highest in the midline, incision in the peritoneum lateral to the midline is less likely to result in bladder injury. Umbilical Area The umbilicus is an important surgical landmark and the most common point of entry during endoscopic surgery. All layers of the anterolateral abdominal wall fuse at the umbilicus (see FIG. 1.5 ). The umbilicus usu- ally lies at a vertical level corresponding to the junction between the third and fourth lumbar vertebrae. This is also the level at which the iliac veins join to form the vena cava and at which the abdominal aorta bifurcates. The skin around the umbilicus is innervated by the 10th thoracic spinal nerve (T10 dermatome). The umbilicus contains the umbilical ring, a defect in the linea alba through which the fetal umbilical vessels passed to and from the umbilical cord and placenta. The umbilical ring provides a window through which umbilical her- nias may develop. The round ligament of the liver and median umbilical and medial umbilical ligaments vari- ably attach to the ring with inconsistent arrangements.

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