Medial crus of superficial inguinal ring

The medial crus of superficial inguinal ring is the medial tendinous margin of the superficial inguinal ring formed by the external oblique aponeurosis. It extends inferomedially from the margins of the ring to attach to the anterior surface of the pubic symphysis.

Together with the lateral crus, it forms the triangular boundaries of the superficial inguinal ring, which represents the external opening of the inguinal canal.

Anatomically, the medial crus is thinner and more vertically oriented than the lateral crus. It lies medial to the spermatic cord in males or the round ligament of the uterus in females as these structures emerge from the superficial inguinal ring. Intercrural fibres bridge the gap between the medial and lateral crura, helping maintain the integrity of the ring and preventing excessive widening during increases in intra-abdominal pressure.

Fibres arising from the medial crus of superficial inguinal ring also contribute to the reflected inguinal ligament (Colles ligament), which passes superomedially behind the spermatic cord to interlace with fibres from the opposite side near the linea alba.