From the posterior abdominal wall through the inguinal canal into the scrotum by birth
Mnemonic
“The testis takes its blood supply and its coverings with it”:
- It develops on the posterior abdominal wall at T10, which is why the testicular artery arises from the aorta at L2 and why testicular pain refers to the periumbilical region (T10)
- It descends behind the peritoneum, reaching the deep ring by 7 months and the scrotum by birth, guided by the gubernaculum
- It acquires three fascial coverings from the three abdominal wall layers as it passes: external spermatic from external oblique, cremasteric from internal oblique, internal spermatic from transversalis fascia
Lymphatic drainage follows the artery, not the skin: the testis drains to para-aortic nodes, while the scrotum drains to superficial inguinal nodes. That distinction is why testicular tumours are staged by abdominal CT and why examining the groin for a testicular tumour is useless.
Failure of obliteration of the processus vaginalis gives a congenital hydrocele or an indirect inguinal hernia.
Expansion
- The testis develops retroperitoneally on the posterior abdominal wall, near the kidney
- The gubernaculum guides it caudally
- The processus vaginalis, an outpouching of peritoneum, precedes it through the abdominal wall
- It reaches the deep ring by about 7 months and the scrotum by about 9 months
The processus vaginalis normally obliterates, leaving only the tunica vaginalis around the testis. Failure explains three conditions:
- Complete patency - indirect inguinal hernia
- Partial patency - communicating hydrocoele
- Isolated segment - encysted hydrocoele of the cord
The abdominal origin also explains why the testis drains its lymph to the para-aortic nodes and takes its blood supply from the abdominal aorta, not from the pelvic or scrotal vessels.