Branches of anterior part of lumbar plexus

Branches of Anterior Part of Lumbar Plexus

The ventral divisions of the anterior rami of the lumbar spinal nerves, which constitute the anterior portion of the lumbar plexus, give rise to several branches. These branches, all of which emerge from or around the psoas major muscle include the following:

1. Obturator Nerve

• Formed by the ventral divisions of the anterior rami of L2–L4.

• The nerve exits from the medial border of the psoas major muscle and passes through the obturator foramen to supply the medial (adductor) muscles of the thigh.

2. Iliohypogastric and Ilioinguinal Nerves

• Both nerves arise from the anterior ramus of L1, which continues as a single nerve trunk that bifurcates into iliohypogastric and ilioinguinal nerves. Some refer to this single trunk as the ventral division of the L1 anterior ramus, as there is no dorsal division.

• These nerves emerge from the lateral border of the psoas major, with the ilioinguinal nerve running inferior to the iliohypogastric nerve.

3. Genitofemoral Nerve

• Formed when distinct roots from the ventral divisions of the anterior rami of L1 and L2 unite. The genitofemoral nerve lies on the anterior surface of the psoas major muscle and later divides into two branches:

• Genital branch: Supplies the cremaster muscle and skin of the genital region.

• Femoral branch: Innervates the skin over the femoral triangle.

4. Accessory Obturator Nerve (if present)

Occasionally, the ventral divisions of the anterior rami of L2 and L3 join to form this nerve. When present, it assists in innervating the hip joint and adjacent muscles.