Lab 5 - Module 3 - Hip and Anterior Thigh - Lumbosacral Plexus and Nerves of the Thigh: Page 1 of 2

READINGS:

Gray's Anatomy for Students (Fourth Edition): Pages: 398-401, 418-422, 433-437, 481-486, 546-548

Lumbar Plexus:

The Lumbar Plexus is the upper portion of the lumbosacral plexus. It is formed by the ventral rami of L1, L2, L3, L4. Nerves of the lumbar plexus only run as far as the knee except for a cutaneous branch which runs to the foot.

Each of the L1-L4 nerve roots splits to form an anterior and posterior division. The branches of the lumbosacral plexus are like those of the brachial plexus. They receive contribution from either the anterior or posterior divisions depending on what structures they supply.

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	Begin with the right pelvis and femur.
	Add the L1 nerve root which gives rise to the iliohypogastric nerve and the ilioinguinal nerve, both primarily cutaneous (they do have some motor innervations to the abdominal muscles that we will discuss later). The iliohypogastric nerve runs over the iliac spine and is susceptible to injury by a direct blow.
	Add the iliohypogastric nerve. A branch off of L1.
	Add the ilioinguinal nerve. A branch off of L1 supplies superomedial thigh.
	Add the genitofemoral nerve. A branch off of L1 travels inferior to unite with a small part of the anterior division of L2 to form the genitofemoral nerve. Iliohypogastric, ilioinguinal, and genitofemoral provide sensation to the lower abdominal and hip area and the genital areas.
	Add the L2 Nerve Root. The Anterior Division contributes to the formation of the Obturator Nerve (gives motor supply to the medial thigh muscles). The Posterior Division which contributes to both the lateral femoral cutaneous and Femoral Nerves (supplies motor to the anterior thigh muscles).
	Add the Lateral Cutaneous Nerve.
	Add the L3 and L4 Nerves. The Anterior Divisions contribute to the formation of the Obturator Nerve. The Posterior Divisions contribute to the formation of the Femoral Nerve.
	Add the Obturator Nerve.
	Add the Femoral Nerve.
	The Anterior Cutaneous branch of the Femoral Nerve supplies the skin of the anterior and medial thigh. (NOT IDENTIFIED IN THIS CADAVER).