Genitofemoral nerve

Origin

The genitofemoral nerve arises from the anterior rami of the first and second lumbar spinal nerves (L1 and L2). It is a mixed nerve, comprising both sensory and motor fibers.

Course

The genitofemoral nerve forms within the substance of the psoas major muscle. It emerges on the anterior surface of the muscle while remaining retroperitoneal. Along its course, it descends deep to the psoas fascia and crosses posterior to the parietal peritoneum, as well as structures like the ureter and gonadal vessels. Near the inguinal region, it pierces the psoas fascia and divides into two terminal branches—the genital branch and the femoral branch—just above the inguinal ligament.

Branches and Innervation

1. Genital Branch

Course:

This branch enters the deep inguinal ring and traverses the inguinal canal. In males, it accompanies the spermatic cord. In females, it follows the round ligament of the uterus.

Innervations:

• Males: Provides motor innervation to the cremaster muscle and sensory innervation to the skin of the upper anterior scrotum. spermatic fasica and tunica vaginalis of testis.

• Females: Supplies sensory innervation to the skin of the mons pubis and labium majus.

2. Femoral branch

Course:

The femoral branch runs along the lateral side of the external iliac artery, passing beneath the inguinal ligament. It enters the femoral sheath lateral to the femoral artery, then pierces the sheath and the fascia lata.

Innervation:

Supplies sensory fibers to the skin covering the upper anterior thigh, specifically in the femoral triangle region.

Fiber types and neural pathways

The genitofemoral nerve comprises both motor and sensory fiber types:

1. General Somatic Afferent (GSA)

Sensory fibers transmit information from the skin of the upper anterior thigh and external genitalia to the spinal cord.

• Pathway: Sensory impulses travel through the genitofemoral nerve → anterior rami of L1 & L2 → spinal nerves → posterior roots → dorsal gray horns of spinal segments L1 and L2.

2. General Somatic Efferent (GSE)

Motor fibers innervate the cremaster muscle.

• Pathway: Signals originate in the anterior gray horns of spinal segments L1 and L2 → anterior rami of L1 & L2 → genital branch of the genitofemoral nerve → cremaster muscle.