Anatomy of Inguinal Canal and Hernia

Inguinal Canal

• The inguinal canal is an oblique passage, 4 cm long, directed downwards, forwards, and medially.
• It extends from the deep inguinal ring to the superficial inguinal ring, just above the medial half of the inguinal ligament.

Inguinal Rings

• The deep inguinal ring is an oval opening in the fascia transversalis, ½ inch above the mid-inguinal point, and immediately lateral to the inferior epigastric artery.
• The superficial inguinal ring is a triangular gap in the external oblique aponeurosis, superolateral to the pubic tubercle, and forms the base of a triangle with the pubic crest.

Boundaries of Inguinal Canal

• The anterior wall is composed of skin, superficial fascia, external oblique aponeurosis, and fleshy fibers of the internal oblique muscle (laterally).
• The posterior wall is composed of fascia transversalis, extraperitoneal tissue, parietal peritoneum, and the conjoint tendon (medially).
• The roof is formed by the arched fibers of the internal oblique and transversus abdominis muscles.
• The floor is formed by the inguinal ligament and the lacunar ligament.

Contents of Inguinal Canal

• The spermatic cord
• The round ligament of the uterus
• The ilioinguinal nerve

Mechanisms of Inguinal Canal

• The obliquity of the inguinal canal and the inguinal rings not lying opposite each other create a flap valve mechanism.
• The superficial inguinal ring is guarded from behind by the conjoint tendon.
• The deep inguinal ring is guarded from the front by the internal oblique muscle.
• Contraction of the external oblique muscle approximates the two crura.

Inguinal Hernia

• Inguinal hernia is more common in males.