Anatomy - Inguinal hernia repair, Rutkow Plug

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 more femoral hernias, men more inguinal hernias). As the area below the inguinal ligament, the inguinal canal is divided into two compartments by a division of the inguinal ligament (arcus iliopectineus): the lacuna vasorum and the lacuna musculorum.

Lacuna vasorum

• Located next to the pubic bone, it serves as the passageway for the external iliac artery and vein (→ femoral artery and vein, arrangement: artery lateral to the vein). Additionally, the femoral branch of the genitofemoral nerve passes through it laterally, and the deep inguinal lymph nodes (Rosenmüller) are found caudally medially within it. The lacuna vasorum represents the internal hernial gap for femoral hernias (through the femoral septum next to the femoral vein).

Lacuna musculorum

• Located lateral to the lacuna vasorum, it serves as the passageway for the psoas major muscle and iliacus muscle (together = iliopsoas muscle), as well as 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, forming a tubular structure. The peritoneum carried along during 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 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 drawn into the scrotum and form the spermatic cord. Through the obliteration of the Proc. vaginalis testis, the connection to the abdominal cavity closes, and typically only its entrance (Vestigium proc. vaginalis testis) remains. In the female embryo, the ovaries do not completely descend due to the pull of the gubernaculum, but remain beside the uterus. Only the Lig. teres uteri, as the former gubernaculum, persists in the inguinal canal. Inadequate obliteration of the Proc. vaginalis testis represents a weakness of 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 Anulus inguinalis profundus, as its cranial end, and the Anulus inguinalis superficialis, as its opening to the outer abdominal wall.

Anulus inguinalis profundus

• Midway between the symphysis and the anterior superior iliac spine in the inner abdominal wall, lateral to the A./V. epigastrica inferior (in the Plica umbilicalis lateralis).

Anulus inguinalis superficialis

• 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 = Crus mediale and laterale 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) as well as 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 (Lig. teres uteri), which extends from the uterus to the deep inguinal ring, passes 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 within the inguinal canal.

For indirect inguinal hernias, the deep inguinal ring serves as the hernial orifice, while for direct inguinal hernias, it is the medial inguinal fossa (medial to the deep inguinal ring and the inferior epigastric artery/vein).

Indirect Inguinal Hernias

• More common, men > women, congenital (open processus vaginalis testis) or acquired (also through the internal inguinal ring in the lateral inguinal fossa, mostly adults), the hernial 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 adults 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.