The spinal cord in cross-section has a central region of darker gray matter and the rest is lighter white matter. The gray matter is made up of neuroglia cells and neuron cell bodies. The white matter is made up of neuron axons, mostly but not all myelinated.
The dorsal horns are the thinner projections of dark matter that jut out from the rest towards the dorsal/back side of the spinal cord. The ventral horns are the wider projections of dark matter towards the ventral/front side of the spinal cord.
The branches coming off on the back/dorsal sides of the spinal cord are called the dorsal roots. They contain the axons of sensory neurons returning to the spinal cord from sensory receptors. Near the spinal cord, there are bulges called dorsal root ganglia. They contain the cell bodies of the neurons heading back to the spinal cord.
The branches coming off on the front/ventral sides are called the ventral roots. They contain the axons of motor neurons heading off to muscles.
The central canal is a narrow hollow center to the spinal cord that is filled with cerebrospinal fluid (CSF).
Lab 10 Exercises 10.4
1. Fill in the names of the indicated structures in Figure 10-13.