CoursesAnatomyAbdomenNerves, vessels and lymphatics of the abdomenLumbar plexus

CoursesAnatomyAbdomenNerves, vessels and lymphatics of the abdomenLumbar plexus

Lumbar plexus

Learning objectives

After completing this study unit you will be able to:

Identify the spinal nerve levels from which the lumbar plexus arises.
Name the terminal branches of the lumbar plexus and their supply areas.

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The lumbar plexus is a collection of spinal nerves located deep in the lumbopelvic region, close to the psoas major muscle. Formed from the anterior rami of spinal nerves L1–L4, this nerve network provides innervation to the muscles, joints and skin of the anterolateral aspects of the pelvis and thigh.

The lumbar plexus has six major terminal branches. According to their anatomical position, the branches can be grouped into anterior or posterior parts: the anterior part largely providing innervation to the pelvis and the posterior part supplying branches to the thigh. Fibres from spinal nerve L4 join with fibres from L5 to form the lumbosacral trunk. This large nerve links the lumbar plexus with the sacral plexus, thus these nerve complexes are often given the combined name of lumbosacral plexus. Together these two plexuses supply all innervation to the pelvis and lower limb.

This video tutorial will provide you with an overview of the lumbar plexus.

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Summary

Key facts about the lumbar plexus
Roots	Spinal nerves L1, L2, L3, L4
Structural organization	Branches from spinal nerve L1 Branches from anterior division of spinal nerves L2-L4 Branches from posterior division of spinal nerves L2-L4
Terminal branches	Iliohypogastric nerve, ilioinguinal nerve, genitofemoral nerve, obturator nerve, lateral femoral cutaneous nerve and femoral nerve.
Function	Motor: innervation of abdominal muscles, flexors of hip joint, extensors of knee joint Sensory: cutaneous innervation of lower abdomen, hip/inguinal/genital regions, thigh (except posterior part), medial aspect of leg

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