Psoas major innervation is provided by which nerve roots?

Psoas major innervation is provided by which nerve roots?

• A. L2-L4 Ventral Primary Rami
• B. L1-L3 Ventral Primary Rami
• C. L1-L2 Dorsal Primary Rami
• D. L4-L5 Ventral Primary Rami

Answer: (B)

Psoas major gets its motor supply from the anterior (ventral) branches of the lumbar nerves, specifically from the ventral rami of L1 through L3. This makes it a direct product of the upper part of the lumbar plexus, aligning with its origin along the lumbar spine and its role as a hip flexor. The dorsal rami supply muscles of the back, not this deep hip flexor, so they aren’t involved. While the femoral nerve (bearing L2-L4 fibers) innervates other hip/ thigh muscles such as iliacus, the direct innervation to psoas major is from L1-L3 ventral rami. Therefore, L1-L3 ventral primary rami is the correct innervation.

Psoas major gets its motor supply from the anterior (ventral) branches of the lumbar nerves, specifically from the ventral rami of L1 through L3. This makes it a direct product of the upper part of the lumbar plexus, aligning with its origin along the lumbar spine and its role as a hip flexor. The dorsal rami supply muscles of the back, not this deep hip flexor, so they aren’t involved. While the femoral nerve (bearing L2-L4 fibers) innervates other hip/ thigh muscles such as iliacus, the direct innervation to psoas major is from L1-L3 ventral rami. Therefore, L1-L3 ventral primary rami is the correct innervation.