What does a medial branch of dorsal rami innervate?

• A. Facet joint
• B. Intervertebral disc
• C. Muscles surrounding the spine
• D. Pelvic floor muscles

Answer: (A)

The medial branch of the dorsal rami primarily innervates the facet joints of the spine. These small joints located between the vertebrae allow for movement and stability in the spinal column, and their innervation is crucial for proprioception and pain perception in that area. The medial branch provides sensory nerve fibers that relay information regarding the position and condition of the joints, which is essential for maintaining balance and stability during movement.

While the intervertebral discs are important structures in the spine, they are primarily innervated by the sinuvertebral nerve and not directly by the dorsal rami. The muscles surrounding the spine receive innervation from the lateral branches of the dorsal rami rather than the medial branches. The pelvic floor muscles, although essential in their functionality, do not receive innervation from the dorsal rami but instead from the sacral and coccygeal nerve roots. Thus, the specific role of the medial branch in innervating facet joints highlights its importance in spinal function and pain modulation.