Internal Structure of the Spinal Cord
The arrangement of white and grey matter and the division of grey matter into ventral, dorsal and lateral columns has been seen.
We have also noted that the white matter of the spinal cord is divisible into anterior, posterior, and lateral funiculi. These funiculi are made up of fibres running up and down the cord.
The relative amount of grey and white matter, and the shape and size of the grey columns, vary at different levels of the spinal cord (Fig. 5.1). The amount of grey matter to be seen at a particular level can be correlated with the mass of tissue to be supplied. It is, therefore, greatest in the region of the cervical and lumbar enlarge-ments which supply the limbs. The amount of white matter undergoes progressive increase as we proceed up the spinal cord. This is a result of the fact that:
a. progressively more and more ascending fibres are added as we pass up the cord, and
b. the number of descending fibres decreases as we go down the cord as some of them terminate in each segment.
In the paragraphs that follow we will consider some details about the grey matter of the spinal cord.