The medial inguinal fossae between the medial and lateral umbilical folds, the inguinal triangles, are potential sites for the less common direct inguinal hernias. The lateral inguinal fossae, lateral to the lateral umbilical folds, are potential sites for the most common type of hernia in the lower abdominal wall—indirect inguinal hernia

inferiorly, the inferior margin of the external oblique aponeurosis thickens and folds back on itself to form the inguinal ligament, a fibrous band extending between the anterior superior iliac spine and the pubic tubercle

The artery of the ductus deferens arises from the inferior vesicle

The transumbilical and median planes divide the abdomen into four quadrants

The inferior limit of the posterior lamina of the rectus sheath is marked by the arcuate line, which defines the point at which the posterior lamina of the internal oblique and the aponeurosis of the transverse abdominal become part of the anterior rectus sheath

the gubernaculum is a fibrous cord connecting the primordial testis to the anterolateral wall at the site of the future deep inguinal ring. The gubernaculum is represented postnatally by the scrotal ligament, which extends from the testis to the skin of the scrotum

The superficial fibers of the external abdominal oblique arising from the middle and lower ribs interdigitate with only those of the serratus anterior

the neurovascular plane of the anterolateral abdominal wall contains the thoracoabdominal nerves, cutaneous branches T7–T11, ventral ramus of T12, iliohypogastric and ilioinguinal nerves, lumbar arteries, and the deep circumflex iliac artery

The inguinal ligament is reinforced in its most medial part by the lacunar ligament, a reflected part or extension from the deep aspect of the inguinal ligament to the pectineal line of the pecten pubis

Genital branch of the genitofemoral, anterior scrotal branches of the ilioinguinal, posterior scrotal branches of the pudendal, and perineal branches of the posterior femoral cutaneous provide the innervation to the scrotum

Some fibers of the inguinal ligament pass upward to cross the linea alba and blend with the lower fibers of the contralateral aponeurosis. These fibers form the reflected inguinal ligament

The deep inguinal ring (entrance to the inguinal canal) is the site of an outpouching of the transversalis fascia approximately 1.2 cm superior to the middle of the inguinal ligament

The cremaster muscle is innervated by the genital branch of the genitofemoral nerve

The midclavicular planes pass through the midpoint of the clavicles to the mid-inguinal points

The aponeuroses of these muscles interlace at the linea alba with their fellows of the opposite side to form the tough, aponeurotic tendinous sheath of the rectus muscle, and the rectus sheath

The iliopubic tract is the thickened inferior margin of the transversalis fascia that appears as a fibrous band running parallel and deep to the inguinal ligament. The iliopubic tract demarcates the inferior edge of the deep inguinal ring

The inguinal canal contains the spermatic cord in the male and the round ligament in the female. The inguinal canal also contains blood and lymphatic vessels and the ilioinguinal nerve in both sexes

The anterolateral abdominal wall includes the cartilages of the 7th–10th ribs and xiphoid process superiorly. Inferiorly it is bounded by the inguinal ligament and the pelvic bone

The testes develop in the extraperitoneal connective tissue in the superior lumbar region of the posterior abdominal wall

The parietal peritoneum is internal to the transversalis fascia and is separated from it by a variable amount of endoabdominal (extraperitoneal) fat. Camper’s fascia and the deep fasciae are all superficial to the extraperitoneal fat.

transversalis fascia lines most of the abdominal wall and covers the deep surface of the transverse abdominal muscle. The deep fascia invests the external abdominal oblique muscle. Both Camper’s and Scarpa’s fascia are located in the inferior part of the abdominal subcutaneous tissue

The cremasteric fascia contains loops of cremaster muscle, which is formed by the lowermost fascicles of the internal oblique muscle arising from the inguinal ligament. The cremasteric fascia is derived from the deep and superficial fascia of the internal oblique

The contents of the rectus sheath include the pyramidalis and rectus abdominis muscles, the superior and inferior epigastric arteries and veins, the lymphatics, and ventral primary rami of T7-T12 nerves

The rectus muscle is anchored transversely by attachments to the anterior layer of the rectus sheath and three or more tendinous intersections

The median umbilical fold represents the remnant of the urachus; the medial umbilical folds are remnants of the occluded fetal umbilical arteries; and the lateral umbilical folds cover the inferior epigastric vessels