Spinal Tracts

Front 1

spinothalamic tract

Back 1

function - pain, sensation, coarse touch and pressure

receives input from cell bodies of afferent fibres that terminate in the dorsal horn, which then decussate to the contralateral spinothalamic tract

terminate in the ventral posterior nucleus of the thalamus -> contains third order neurons which then project to the somatosensory cortex

Front 2

spinocerebellar tract

Back 2

function - information derived from muscle spindles, golgi tendon organs, tactile receptors -> used in control of posture and coordination of movement

cell bodies in base of dorsal horn input from afferent nerves terminating in this area
dorsal tract neuron ascends ipsilaterally to enter the cerebellum by the inferior cerebellar peduncle
ventral tract neuron decussates ascends in the contralateral side enters the cerebellar via the superior cerebellar peduncle
tract neuron terminates in the cerebellar cortex -> predominantly within the vermis

Front 3

corticospinal tract

Back 3

function - control of voluntary, discrete, skilled movement

arise from cell bodies in the cerebral cortex -> mostly the precentral gyrus and the primary motor cortex
leave cerebral hemisphere pass through the corona radiata, internal capsule and enter the crus cerebri of the midbrain
pass through ventral portion of the pons
in the medulla the fibres form two prominent columns on the ventral surface known as the pyramids -> here 75-90% of fibres undergo decussation and enter the contralateral corticospinal tract, other 10-25% remain ipsilateral and enter the ventral corticospinal tract and decussate near termination
axons mostly terminate in the dorsal horn

Front 4

rubrospinal tract

Back 4

control over tone of limb flexor muscles (excitory)

orginates from red nucles of the mid brain tegmentum
axons cross in the ventral tegmental decussation, then descend in the spinal cord
terminating in the ventral horn

red nucleus receives afferent fibres form the motor cortex and the cerebellum -> this tract is a non-pyramidal route by which motor cortex and cerebellum can influence spinal motor activity

Front 5

tectospinal tract

Back 5

thought to mediate reflex movements in response to visual stimulus

axons pass ventromedially around periaqueductal grey matter corss in the dorsal tegmental decussation
superior colliculus recieves visual input --> tectospinal tract function

Front 6

vestibulospinal tract

Back 6

maintain extensor muscle tone in the anti-gravity maintenance of posture

arise from vestibular nuclei -> pons and medulla near fourth ventricle, input from labyrinth system by way of vestibular nerve and cerebellum

axons from lateral vestibular nucleus descend ipsilaterally as the lateral vestibular spina tract
fibres mediate excitory influences upon extensor motor neurons
medial vestibular nucleus contributes descending fibres to the ipsilateral medial longitudial fasciculus, also known as the medial vestibulospinal tract

Front 7

reticulospinal tract

Back 7

influence voluntary movement, reflex activity and muscle tone by controlling the activity of both alpha and gamma motor neurons
also mediate pressor and depressor effects upon the circulatory system and are involved in the control of breathing

arise from reticular formation of hte pons and medulla
axons from the pontine recticular formation descend ipsilaterally as the medial reticulospinal tract

axons from the medulla descends bilaterally in the lateral reticulospinal tract
both tracts located in the ventral funiculus