Anatomy - Lumbar Plexus

Drawing on whiteboard the structure and branches of the lumbar plexus.
The lumbar plexus is formed within the substance of the psoas major by the union of ventral rami of L1–L3 lumbar nerves and a larger upper part of the ventral ramus of L4 nerve.
The lower smaller part of the ventral ramus of L4 nerve joins with the ventral ramus of L5 nerve to form the lumbosacral trunk which takes part in the formation of sacral plexus.
The ventral ramus of the 4th lumbar nerve is sometimes called nervi furcalis, because it forms the connecting link between the lumbar and sacral plexuses.
The L2, L3, L4 nerves divide into dorsal and ventral divisions. The dorsal divisions of L2, L3, L4 unite to form the femoral nerve. The ventral divisions of L2, L3, and L4 join to form the obturator nerve. The accessory obturator nerve if present is derived from the ventral
branches of the L3, L4 nerves.
The principal branches of the lumbar plexus are the
femoral nerve and the obturator nerve.
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