Function Of Descending Tracts

Front 1

Corticospinal tracts

Back 1

pathways concerned with voluntary, discrete, skilled movements (especially those of distal parts of limbs)

Front 2

Reticulospinal tracts

Back 2

facilitate or inhibit activity of alpha and gamma motor neurons in anterior gray columns and thus can facilitate or inhibit voluntary movement or reflex activity

Front 3

Tectospinal tract

Back 3

concerned with reflex postural movements in response to visual stimuli

Front 4

Rubrospinal tract

Back 4

acts on both alpha and gamma motor neurons in anterior gray columns and facilitates activity of flexor muscles and inhibits activity of extensor or antigravity muscles

Front 5

Vestibulospinal tract

Back 5

facilitates activity of extensor muscles by acting on motor neurons in anterior gray columns, inhibits activity of flexor muscles and is concerned with postural activity associated with balance

Front 6

Olivospinal tract

Back 6

may play a role in muscular activity

Front 7

Descending autonomic fibers

Back 7

concerned with control of visceral activity

Front 8

Cerebellar circuits

Back 8

Cerebellum receives information from cerebral cortex, including motor areas and is also informed of changes in lengths and tensions of muscles, position and angular movements of the head

Output of cerebellar nuclei: primary a supplementary motor areas, through a relay in the posterior division of the ventral lateral thalamic nucleus (VLp)

Other cerebellar efferents influence lower motor neurons through connections with vestibular nuclei and nuclei of reticular formation

Front 9

Basal Ganglia

Back 9

Motor circuitry of basal ganglia involved in transfer of information from whole of neocortex to motor areas, in particular the premotor and supplementary
motor areas

Striatum serves as repository of instructions for fragments of learned movements