Lumbosacral trunk

Lumbosacral trunk is a part of the human anatomy that is formed by the union of the fourth and fifth lumbar nerves with the first sacral nerve. The lumbosacral trunk is a significant component of the lumbosacral plexus, which is a network of nerve fibers that supplies the lower limb.

Etymology

The term "lumbosacral" is derived from the Latin words "lumbus" meaning loin and "sacrum" meaning sacred bone. The term "trunk" in this context refers to a large nerve, artery, or vein, from which smaller branches arise.

Anatomy

The lumbosacral trunk is formed anterior to the sacroiliac joint by the union of the whole of the anterior division of the fifth lumbar nerve and a part of that of the fourth. It descends into the pelvis and, under the pyriformis muscle, joins with the first sacral nerve to form the sciatic nerve.

Function

The lumbosacral trunk contributes to the innervation of the lower limb. It carries fibers that will become part of the sciatic nerve, which provides motor and sensory innervation to the lower extremity.

Clinical significance

Damage to the lumbosacral trunk can result in motor neuron disease, sensory neuron disease, or a combination of both. This can lead to a range of symptoms, including muscle weakness, numbness, and pain in the lower extremities.

Related terms

• Lumbar nerves
• Sacral nerves
• Lumbosacral plexus
• Sciatic nerve
• Sacroiliac joint
• Pyriformis muscle

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  Diagram of the lumbar plexus
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  Gray's Anatomy illustration of the lumbosacral trunk
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  Lumbosacral trunk
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  Lumbosacral trunk