Inguinal canal

The inguinal canal is a passage in the anterior abdominal wall that transmits structures from the pelvis to the perineum formed by the fetal migration of the gonad from the abdomen into the labioscrotal folds.

Gross anatomy

The inguinal canal has an oblique course, is 4 cm in length and has two openings:

1. deep inguinal ring: a round opening in the transversalis fascia found 1 cm superior to the inguinal ligament and 1 cm lateral to the inferior epigastric arteries
2. superficial inguinal ring: a V-shaped opening in the external oblique aponeurosis that is superior and lateral to the pubic tubercle (within Hesselbach's triangle) ^1,2

Deep inguinal ring

The deep inguinal ring is bounded by the following:

• laterally by the angle between the transversus abdominis and inguinal ligament
• medially lies the inferior epigastric vessels

Older authors and texts refer to the deep ring as the abdominal inguinal ring.

Superficial inguinal ring

The superficial inguinal ring, as described, is an inverted "V" shaped, triangular opening in the medial end of the external oblique aponeurosis, above and lateral to the pubic tubercle. The lateral arm of the "V" is the lateral crus and its medial arm, the medial crus. The spermatic cord (in males)/round ligament (in females) overlies the pubic tubercle. 

• lateral crus of the "V" is attached to the pubic tubercle
• medial crus of the "V" is attached to the pubic crest, near the symphysis
• posterior crus arises from the attachment of the lateral crus, whereby some fibers (reflected part of the inguinal ligament) pass up behind the cord to attach to the rectus sheath, blending with fibers of the opposite side

Older authors and texts refer to the superficial ring as the subcutaneous inguinal ring.

Boundaries

The following structures contribute to the walls of the inguinal canal ¹:

• superior wall (roof): internal oblique muscle and transversus abdominis muscle
• anterior wall: external oblique aponeurosis and internal oblique aponeurosis
• inferior wall (floor): inguinal ligament and lacunar ligament
• posterior wall: transversalis fascia and conjoint tendon

MALT is a mnemonic to recall this. 

Contents

• males & females: ilioinguinal nerve ^1,2, genital branch of genitofemoral nerve
• males: spermatic cord (and contents)
• females: round ligament

Related pathology

• inguinal hernia