The genitofemoral nerve is a mixed nerve that originates from the lumbar plexus and innervates the cremaster muscle as well as the skin of the upper anterior thigh and anterior scrotum. It arises from the ventral rami of the first and second lumbar nerves (L1 - L2).

This nerve is formed within the substance of the psoas major muscle (Read more!). After it arises, it descends obliquely through the muscle and pierces the psoas major at its upper or mid-aspect, emerging on its anterior surface.

The genitofemoral nerve then continues to descend behind the peritoneum on the anterior surface of the psoas major, crossing posterior to the ureter (Read more!) and testicular vessels. Along its course, it also passes posterior to the left colic artery and inferior mesenteric vein on the left side, and the ileocolic artery and ileocolic vein on the right side.

At the lower aspect of the muscle, and at a variable distance above the inguinal ligament, it splits into two branches:

Femoral branch - descends lateral to the external iliac artery and passes beneath the inguinal ligament, going through the lacuna vasorum; it enters the femoral sheath lateral to the femoral artery, passes through the anterior lamina of the femoral sheath, and pierces the cribriform fascia of the saphenous opening of the fascia lata of the thigh; it innervates the skin overlying the femoral triangle and the anterior, upper, and medial sides of the thigh; it is also known as the lumboinguinal nerve;
Genital branch - crosses the lower portion of the external iliac artery and enters the inguinal canal via the deep inguinal ring; within the canal, it follows the course of the spermatic cord; innervates the cremaster and dartos muscles, as well as the skin of the scrotum; it also provides sensory fibers to the spermatic fascia and tunica vaginalis of the testicle; it is also known as the external spermatic nerve.

Sometimes, the genitofemoral nerve divides close to its origin, or the genital and femoral branches may arise from the lumbar plexus as separate branches. In such cases, either branch may originate entirely from the L1 or L2 nerves. In fact, the genitofemoral nerve is considered one of the most variable nerves of the lumbar plexus.

Occasionally, this nerve or one of its branches may be absent. In such cases, the ilioinguinal nerve replaces the genital branch, while the lateral femoral cutaneous nerve or the femoral nerve replaces the femoral branch.

Note: Testicular torsion may entrap the genitofemoral nerve. Loss of the cremasteric reflex, which is mediated by the genital branch of the genitofemoral nerve, is a clinical sign of testicular torsion.

Unlock with Premium

Genitofemoral nerve