Neurology

Question 1

Central Nervous System

(CNS)

Answer 1

• CNS consists of the brain contained in the cranial cavity and the spinal cord, which lies in the vertebral canal
• Particular on transverse sections it can be seen that the CNS is composed of two types of tissue:

1. Grey Matter- composed of nerve cell bodies and unmyelinated nerve processes (fibres)
2. White Matter- composed largely of myelinated nerve processes (fibres). The mass of myelin sheaths accounts for the white colouration in the fresh state

Question 2

Peripheral Nervous System

(PNS)

Answer 2

• The PNS consists of nerves
• These include the cranial nerves arising from the brain and the spinal nerves arising from the spinal cord
• Yet again, the whitish color of nerves is explained by the presence of the myelin sheaths surrounding the nerve processes. Also explains the fact that even fine nerves can be preserved on dissection by their tendancy not to “fray” unlike strands of connective tissue

Question 3

Ganglia

(PNS)

Answer 3

• In various locations of the PNS, ganglia can be identified (e.g. dorsal root or spinal ganglia on the dorsal roots of spinal nerves and autonomic ganglia in for example the sympathetic chain)
• Ganglia consist of collections of nerve cell bodies and look like smooth rounded expansions or star-shaped expansions on appropriate nerve trunks