Spinal Nerve Roots

Each spinal nerve is connected to the spinal cord by two roots called the dorsal root and the ventral root. The spinal nerve roots serve as one-directional information flow into and out of the spinal cord. Even though each spinal nerve contains both sensory and motor fibers, the sensory fibers enter the spinal cord through the dorsal root, and motor fibers exit the spinal cord through the ventral root. Think of the spinal nerve roots as the in and out doors of the spinal cord.

Since the dorsal root contains axons of sensory neurons, it is also known as the sensory root. The cell bodies of the sensory neurons aggregate within the dorsal root, forming a recognizable bump called the dorsal root ganglion.

Figure 1: Spinal nerve roots