What is the innervation of the interspinalis muscles?

The interspinalis muscles, which are small muscles located between adjacent spinous processes of the vertebrae, are primarily responsible for assisting with extension and stabilization of the spine. They receive their innervation from the dorsal rami of spinal nerves. The dorsal rami provide motor innervation to the muscles located in the back, making them specifically suited to innervate the interspinalis.

In the context of spinal anatomy and function, understanding that the dorsal rami deliver signals to deep back muscles, including the interspinalis, helps emphasize their role in movement and maintaining posture. This innervation is crucial for the coordination and functioning of the musculature responsible for movements of the spine.

The other options suggest incorrect or less relevant sources of innervation. Ventral rami primarily serve the anterior aspect of the body, thoracic spinal nerves would be too specific without referencing overall spinal anatomy, and the cervical and lumbar plexus only innervate groups of muscles within their respective regions rather than specifically targeting the interspinalis muscles.