VAN 121: Veterinary Gross Anatomy-II (2+2)

TRACTS OF SPINAL CORD

• These consist of bundles of medullated nerve fibres in the dorsal, lateral or ventral white columns or funiculi of the white mater of spinal cord. The fibres having similar origin, termination and function are grouped together and are called as tracts or fasciculi.
• The tracts may be classified as

Sensory or ascending tracts  

• Sensory or ascending tracts conveying impulses from the periphery to the brain.
• They are generally formed (with exceptions) by the axons of neurons in the dorsal gray column, which in turn receive sensory impulses from the peripheral receptors, through the dorsal roots of spinal nerves after relay in the spinal or dorsal root ganglia. View animation

Motor or descending tracts

• Motor or descending tracts  conveying impulses from the brain to the peripheral effectors.
• They arise from different centres or nuclei in the brain, descend in the white mater of spinal cord and finally end in synaptic relations with either somatic motor neurons in the ventral gray column (supplying skeletal muscle) or visceral motor neurons in the lateral gray column (supplying glands, plain muscle and cardiac muscle). View animation

Intersegmental tracts

• Intersegmental tract connecting different segments of the spinal cord.