The spinal cord cross-section has three main parts, grey matter, white matter, and the central canal. The gray matter is shaped like the letter H (or a butterfly) and is surrounded by white matter. In the center of the spinal cord, there is the central canal, which contains cerebrospinal fluid. The gray matter on both sides of the spinal cord is divided into horns. The two anterior projections are called ventral horns, which innervate skeletal muscles.

The dorsal (or posterior) horns usually contain interneurons that receive incoming sensory information from sensory neurons.

The thoracic and upper lumbar regions of the spinal cord have a small projection between the dorsal and the ventral horns, called lateral horns. These lateral horns contain autonomic motor neurons that regulate various organs.

Figure 1: Internal Structure of the Spinal Cord