The inguinal region of the body, also known as the groin, is located on the lower portion of the anterior abdominal wall, with the thigh inferiorly, the pubic tubercle medially, and the anterior superior iliac spine (ASIS) superolaterally. The inguinal canal is a tubular structure that runs inferomedially and contains the spermatic cord in males and the round ligament in females. The floor of the inguinal canal is the inguinal ligament, otherwise known as the Poupart ligament, which is formed by the external oblique aponeurosis as it folds over and inserts at the ASIS down to the pubic tubercle. This folded edge is called the shelving edge and is important for surgeons in hernia repairs. The inguinal canal is a conduit where structures pass, which has significance from an embryological and pathological standpoint.
Formation of the inguinal canal in males occurs concurrently with testicular descent prior to birth. The testes originate in the posterior abdominal cavity and, through certain signals, descend and ultimately reside in the scrotal cavity. This descent of the testis in males creates an inherent weakness in the abdominal wall at the inguinal canal. This weakness is important in the development of inguinal hernias. During normal testicular descent, the testis migrates caudally and traverses through various layers of the abdominal wall to end up in the scrotum. In females, the final event results in the ovum descending into the pelvis.
This process of testicular decent is assisted by a structure known as the gubernaculum, which forms on the inferior aspect of the gonad and signals descent and ultimately adherence of the gonad in its final destination. Failure for this event to occur in males leads to an undescended testis (testicle), otherwise known as cryptorchidism.
The muscle and fascial layers of the anterior abdominal wall continue inferiorly to form the layers covering the spermatic cord as it continues through the inguinal canal and into the scrotum. Around the 12th week of gestation, the processus vaginalis forms, which is an embryonic developmental outpouching of the peritoneum.
Ultimately, the connection of the processus vaginalis with the peritoneal cavity obliterates and it becomes a serous sac surrounding the testis, called the tunica vaginalis testis.