Corpus: Inguinal canal

The inguinal canal runs through the anterior abdominal wall in the inguinal region. In men it contains the spermatic cord (funiculus spermaticus), in women the uterine ligament (ligamentum teres uteri), as well as the ilioinguinal nerve and other structures.

Course[Bearbeiten]

Coming from the dorsal, cranial and lateral sides, the inguinal canal runs obliquely through the abdominal wall to the ventral, caudal and medial sides. It is about 4 - 6 cm long (variable). Due to the oblique course, there is a lower risk of a hernial orifice forming.

Openings[Bearbeiten]

Anulus inguinalis profundus[Bearbeiten]

The inner opening of the inguinal canal is known as the inner inguinal ring (annulus inguinalis profundus). Dissection of the transverse fascia on the posterior side of the abdominal wall is required for visualisation. There, the transversalis fascia radiates into the inguinal canal and continues into the inguinal canal as the internal spermatic fascia, enveloping the spermatic cord. In the case of a lateral (indirect) inguinal hernia, the internal inguinal ring serves as a hernial orifice.

Anulus inguinalis superficialis[Bearbeiten]

The outer opening of the inguinal canal is the external inguinal ring (annulus inguinalis superficialis). It is formed by a slit in the aponeurosis of the obliquus externus abdominis muscle and is covered by the superficial abdominal wall fascia (fascia abdominalis superficialis). After removal of the fascia, it appears as an inverted V-shaped opening a few finger widths lateral to the pubic tuberosity.

Limitations[Bearbeiten]

roof[Bearbeiten]

The obliquus internus abdominis and transversus abdominis muscles form the roof of the inguinal canal with their caudal edges.

Bottom[Bearbeiten]

The floor of the inguinal canal is formed by the inguinal ligament (lateral) and the reflex ligament (medial), which arises from fibres of the aponeurosis of the external oblique muscle.

Anterior wall[Bearbeiten]

The aponeurosis of the external oblique muscle of the abdomen (external aponeurosis) forms the anterior border of the inguinal canal. Laterally, the anterior wall is reinforced by fibres of the obliquus internus abdominis muscle.

Posterior wall[Bearbeiten]

The posterior wall is formed by reinforced tracts of the transversalis fascia.

Piercing structures[Bearbeiten]

...in men[Bearbeiten]

• Ilioinguinal nerve (outside the spermatic funiculus)
• Funiculus spermaticus with
  • ductus deferens (vas deferens)
  • Blood vessels
    • testicular artery
    • Vena testicularis or plexus pampiniformis
    • Deferent duct artery
    • Vena ductus deferentis
    • Cremasteric artery
    • Cremasteric vein
  • Nerves
    • Genital ramus of the genitofemoral nerve
    • Plexus testicularis
    • Deferent duct plexus
    • Vegetative nerve fibres
  • Lymphatic vessels
• Processus vaginalis peritonei

The cremaster muscle does not pass through the entire inguinal canal as it is a split-off from the abdominal wall muscles. Its fibres attach to the funiculus spermaticus from the outside in the inguinal canal.

...in women[Bearbeiten]

• ilioinguinal nerve (outside the ligamentum teres uteri)
• Ligamentum teres uteri
• Arteria ligamenti teretis uteri
• Lymphatic vessels
• Genital ramus of the genitofemoral nerve

A small protrusion of the peritoneum, the so-called processus vaginalis peritonei, develops on three sides of each gubernaculum and forms an almost ring-shaped, blind-ending cavity. When the vaginal process grows inferiorly and leads to a sock-like protrusion of the abdominal wall layers, the inguinal canal is formed.

The first layer is the transversalis fascia under the transversus abdominis muscle, which later becomes the internal spermatic fascia of the spermatic cord. The vaginal process does not meet the muscle itself as it has a gap in this region. The processus vaginalis then takes up the fibres and fascia of the obliquus internus abdominis muscle. These become the fascia cremasterica of the spermatic cord. Finally, the processus vaginalis takes up a thin layer of the obliquus externus abdominis muscle, which becomes the fascia spermatica externa.

When the vaginal process expands, it hollows out the inguinal canal and forms a cavity in which the testicles descend in men (descensus testis). In women, the vaginal process remains rudimentary and normally recedes in the course of development.

See main article: Inguinal canal (embryology)

The inguinal canal is a functional weak point, which in certain cases can cause the peritoneum to protrude through the abdominal wall. This condition is known as an inguinal hernia.

• Schoenwolf et al - Larsen's Human Embryology, 5th edition, 2015