The spinal cord

Spinal cord overview

The spinal cord is part of the nervous system and runs the length of the back, extending from the base of the brain at the medulla to about the waist at the conus medularis. The spinal cord is housed within the spinal column. Within the column, the cord is surrounded by cerebral spinal fluid. This fluid acts as a buffer to protect the spinal cord from damage sustained by striking the inside of the vertebral column.

Spinal cord illustration

The diagram below illustrates the main anatomical features of the spinal cord. The function of the main areas highlighted are listed below.

Spinal Nerve – Carries nerve impulses
Dorsal Root Ganglion – Receives impulses from other areas such as the skin for transmission to the brain.
Central Canal – Fluid filled space running the length of the spinal cord
Grey Matter – Contains nerve cell bodies.
White Matter – contains the axons of the spinal cord.

Spinal cord function

The spinal cord carries out two main functions, and is effectively a highway for communication of signals.

Firstly, it connects a large part of the nervous system to the brain. Nerve impulses are transmitted to the spinal cord through sensory neurons. These impulses are then transmitted by the spinal cord to the brain. This pathway is known as the ascending tract of nerves. In the reverse process, impulses are generated in the brain, which are transmitted down the cord and leave by the motor neurons. This pathway is known as the descending tract of nerves.

Secondly, the spinal cord acts as a co-ordinating centre in order to produce simple reflexes such as the withdrawal reflex.

The area within the spinal column beyond the end of the spinal cord is called the cauda equina. The nerves that branch out from the spinal cord to the other parts of the body are called lower motor neurons (LMNs) and dorsal root sensory neurons.