The deep inguinal ring is a defect in the transversalis fascia and lies lateral to the inferior epigastric vessels. Which layer of the abdominal wall forms the internal spermatic fascia as it invaginates during testicular descent?

• A Internal oblique muscle (cremaster muscle is derived from this)
• B External oblique aponeurosis (forms the external spermatic fascia)
• C Scarpa's fascia (becomes Dartos fascia of scrotum)
• D Transversalis fascia ✓

Explanation

As the processus vaginalis (peritoneal diverticulum) and then the testis descend through the inguinal canal, they invaginate layers of the abdominal wall as they pass, acquiring coverings: (1) transversalis fascia → internal spermatic fascia (as it passes through the deep ring); (2) internal oblique muscle → cremaster muscle and fascia (picked up in the canal); (3) external oblique aponeurosis → external spermatic fascia (picked up at the superficial ring). Scarpa's fascia becomes Colles' fascia in the perineum and Dartos smooth muscle in the scrotum but is NOT a direct covering of the cord. This layered acquisition is the anatomical basis for the triple-layer repair in hernia surgery.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.