Central Nervous System (CNS)

Topic Content:

The central nervous system consists of the brain enclosed in the skull and the spinal cord, a long narrow tube which runs through most of the length of the vertebral column in the neural canals.

Spinal Cord:

The spinal cord consists of thousands of neurones clustered to form a cylinder of nervous tissue, which runs down the length of the neural canal at the back of vertebrates.

It is enveloped within these membranes.

(i) The meninges.

(ii) The central/spinal canal.

A transverse section of the spinal cord reveals that it has:

(i) White matter: This contains the axons of motor and sensory neurons.

(ii) Grey matter: It is H-shaped and in the inner part of the spinal cord. Intermediate, neurons, cell bodies, and motor neurons are present here.

(iii) Central canal: It contains cerebrospinal fluid in living animals. It is a hole in the centre of the spinal cord.

(iv) Pia mater: This is a membrane that surrounds the spinal cord, other membranes are the Arachnoid mater and Dura mater.

Functions of the Spinal Cord:

1. Coordinates