MAVO Year 4 · Coordination and control · Section 10.3

The spinal cord

What is the spinal cord?

The spinal cord forms part of the central nervous system. It extends down from the brainstem through the vertebral canal and, in adults, ends in the upper lumbar region rather than at the bottom of the spine. Nerve roots continue below it. The vertebral column and protective membranes called meninges surround it. Cerebrospinal fluid provides additional cushioning.

The spinal cord carries information between the brain and much of the body and coordinates many reflexes.

Grey and white matter

The inner region of the spinal cord is grey matter, containing many neuron cell bodies, including those of motor and relay neurons, as well as synapses and other structures. Around it lies white matter, containing many axons carrying signals up and down the cord. Its pale appearance is largely due to myelin around many of these axons.

Sensory and motor pathways

Sensory fibres carrying information such as touch or pain enter through the dorsal roots, at the back of the spinal cord. The cell bodies of these sensory neurons lie in dorsal root ganglia, swellings just outside the cord.

Motor fibres leave through the ventral roots, at the front, carrying signals towards muscles and other effectors. Sensory and motor roots join to form mixed spinal nerves. These nerves therefore carry information both towards and away from the spinal cord.