Anatomy - Inguinal hernia repair, transabdominal preperitoneal hernioplasty (TAPP)

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 hernia 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 division 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). The femoral branch of the genitofemoral nerve passes through it laterally. Caudally medially, 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 drawn into the scrotum by the gubernaculum testis, as a tubular structure. The peritoneum carried along during this descent remains as an outpouching in the inguinal canal (Proc. vaginalis testis) and extends to the epididymis. The layers of the abdominal wall thus become comparable sheaths in this pouch: Fascia transversalis → Fascia spermatica interna, M. obliquus internus abdominis → M. cremaster, Fascia of M. obliquus externus abdominis → Fascia spermatica externa, no covering by 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 drawn into the scrotum and form the spermatic cord. By 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 Lig. teres uteri, 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

• Centrally located 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, with the upper edge pointing cranially, the lower edge formed by the inguinal ligament, sides = medial and lateral crus with intercrural fibers for stabilization.

Anterior Wall

• Fascia of the external oblique muscle, laterally reinforced by fibers of the internal oblique muscle → Inguinal ligament and → Cremaster muscle

Posterior Wall

• Transversalis fascia, medially reinforced by the inguinal falx (= tendon of the transversus abdominis muscle and internal oblique muscle)

Superior Wall

• Transversus abdominis muscle and internal oblique muscle (fiber course from the inguinal ligament to the medial inguinal falx)

Inferior Wall

• Medial inguinal ligament (= reflected ligament) and a groove formed by the external oblique muscle for the spermatic cord.

In males, the inguinal canal contains the spermatic cord (Funiculus spermaticus) with the ductus deferens, the artery of the ductus deferens (from the inferior vesical artery) and the testicular artery (from the aorta), the venous pampiniform plexus, the cremasteric artery/vein, the genital branch of the genitofemoral nerve to the cremaster muscle, as well as sympathetic nerve fibers and lymphatic vessels, surrounded by the internal spermatic fascia, the cremasteric fascia, and the external spermatic fascia. In females, the inguinal canal contains the round ligament of the uterus, which extends from the uterus to the deep inguinal ring, through the inguinal canal to the superficial inguinal ring, and finally ends at the labia majora. Additionally, lymphatic vessels are present. The ilioinguinal nerve partially runs in the inguinal canal.

Hernial orifices for indirect inguinal hernias are represented by the deep inguinal ring, and for direct inguinal hernias by the medial inguinal fossa (medial to the deep inguinal ring and the inferior epigastric artery/vein).

Indirect Inguinal Hernias

• More common, men > women, congenital (patent processus vaginalis) or acquired (also through the internal inguinal ring in the lateral inguinal fossa, mostly adults), the hernia sac runs lateral to the epigastric vessels and extends into the scrotum or labia majora.

Direct Inguinal Hernias

• Mostly acquired, in adults men > women, protrusion of the peritoneum and transversalis fascia in the medial inguinal fossa (= Hesselbach's triangle/inguinal triangle, medial to the epigastric artery/vein), medially bounded by the transversus abdominis muscle, caudally by the inguinal ligament, usually exiting through the external inguinal ring → scrotum/labia majora.

Femoral Hernias

• Mostly acquired, in adult women > men, through the femoral canal in the medial thigh (medial to the vascular lacuna) along with the femoral artery/vein, femoral branch of the genitofemoral nerve, and lymphatic vessels.