Anatomy - Inguinal hernia repair, Shouldice

Inguinal region from the inside: (1) Inferior epigastric artery and vein, (2) medial = direct inguinal hernia opening, (3) femoral hernia opening, (4) pectineal ligament (Cooper), (5) ductus deferens, (6) external iliac artery and vein, (7) testicular artery and vein, (8) iliopubic tract, (9) lateral = indirect inguinal hernia opening. The inguinal region (transition between the anterior abdominal wall and lower extremity) has several weak points through which a hernial sac with or without contents can protrude through the abdominal wall (women are more prone to femoral hernias, men to inguinal hernias). Below the inguinal ligament, the inguinal canal is divided into two compartments by a split of the inguinal ligament (iliopectineal arch): the vascular lacuna and the muscular lacuna. Vascular lacuna

• Located next to the pubic bone, it is the passageway for the external iliac artery and vein (→ femoral artery and vein, arrangement: artery lateral to the vein). Completely lateral, the femoral branch of the genitofemoral nerve passes through it. Caudally medial, the deep inguinal lymph nodes (Rosenmüller) are found here. The vascular lacuna represents the internal hernia gap for femoral hernias (through the femoral septum next to the femoral vein).

Muscular lacuna

• Located lateral to the vascular lacuna, it is the passageway for the psoas major muscle and iliacus muscle (together = iliopsoas muscle) as well as for the femoral nerve and lateral femoral cutaneous nerve (cranially).

 The inguinal canal forms during the development of the gonads in the male embryo through the descent of the testes, which are pulled into the scrotum by the gubernaculum testis, as a tubular structure. The peritoneum accompanying this descent remains as a protrusion in the inguinal canal (Proc. vaginalis testis) and extends to the epididymis. The layers of the abdominal wall thus become comparable coverings in this pouch: Fascia transversalis → Fascia spermatica interna, M. obliquus internus abdominis → M. cremaster, Fascia of the M. obliquus externus abdominis → Fascia spermatica externa, no covering by the M. transversus abdominis, as it ends more cranially. Blood vessels (A. and V. testicularis) as well as the vas deferens (Ductus deferens) and nerves (N. ilioinguinalis from Pl. lumbalis) are also pulled into the scrotum and form the spermatic cord. Through obliteration of the Proc. vaginalis, the connection to the abdominal cavity closes, typically leaving only its entrance (Vestigium proc. vaginalis). In the female embryo, there is no complete descent of the ovaries due to the pull of the gubernaculum; instead, they remain beside the uterus, and only the round ligament of the uterus, as the former gubernaculum, persists in the inguinal canal. Inadequate obliteration of the Proc. vaginalis represents a weak point in the abdominal wall and the starting point for inguinal hernias. The inguinal canal runs approximately 4 cm long in a medio-caudal direction just above the inguinal ligament parallel to it and lies between the deep inguinal ring, as its cranial end, and the superficial inguinal ring, as its opening to the outer abdominal wall. Deep inguinal ring

• Midway between the symphysis and the anterior superior iliac spine in the inner abdominal wall, lateral to the inferior epigastric artery/vein (in the lateral umbilical fold).

Superficial inguinal ring

• Above the pubic tubercle in the fascia of the M. obliquus externus abdominis, upper edge pointing cranially, lower edge formed by the inguinal ligament, sides = medial and lateral crus with intercrural fibers for stabilization.