What is the spinal level for the lumbosacral trunk?

What is the spinal level for the lumbosacral trunk?

• A. L3, L4
• B. L4, L5
• C. L2, L3, L4
• D. L1, L2

Answer: (B)

The lumbosacral trunk is formed by the ventral rami of L4 and L5. This trunk travels into the pelvis and joins with contributions from the sacral roots to help form the sacral plexus. That connection is what bridges the lumbar and sacral networks that ultimately innervate the lower limb, so L4 and L5 are the spinal levels involved. Other pairings won’t form this trunk because they miss one of the crucial segments needed to connect the lumbar and sacral plexuses.

The lumbosacral trunk is formed by the ventral rami of L4 and L5. This trunk travels into the pelvis and joins with contributions from the sacral roots to help form the sacral plexus. That connection is what bridges the lumbar and sacral networks that ultimately innervate the lower limb, so L4 and L5 are the spinal levels involved.

Other pairings won’t form this trunk because they miss one of the crucial segments needed to connect the lumbar and sacral plexuses.