Descending Tracts

Question 0

Extrapyramidal tracts

Answer 0

Rubrospinal
Tectospinal
Medial and lateral vestibulospinal
Reticulospinal

Question 1

Pyramidal tracts

Answer 1

Anterior corticospinal
Lateral corticospinal
Corticobulbar

Question 2

Anterior corticospinal

Answer 2

Decussate near termination
Arise from cerebral cortex
Pass through corona radiata and internal capsule
Pass through ventral pons
Form pyramids on ventral surface of medulla

Question 3

Lateral corticospinal

Answer 3

75-95% of neurones on the common pathway decussate, entering the contralateral lateral corticospinal tract
Decussation occurs in medulla

Question 4

Corticobulbar

Answer 4

Supplies head and neck
Arise from lateral part of primary motor cortex - same inputs as corticospinal tracts
Terminate at motor nuclei of cranial nerves
Most innervate bilaterally (not 7 and 12)

Question 5

Pyramidal tract functions

Answer 5

Control voluntary, discrete movements

Question 6

Extrapyramidal tract functions

Answer 6

Involuntary and automatic control of musculature
Tone
Balance
Posture
Locomotion

Question 7

Rubrospinal tract

Answer 7

From red nucleus of midbrain
Decussate as emerge
Red nucleus receives input from motor cortex and cerebellum
Function unclear - fine control of hand movements?

Question 8

Tectospinal tract

Answer 8

From superior colliculus of midbrain
Decussate as they emerge
Most terminate at cervical level
Coordinate movement of head in relation to visual stimuli

Question 9

Medial and lateral vestibulospinal

Answer 9

From medial and lateral vestibular nuclei respectively
Input from organs of balance
Both remain ipsilateral

Question 10

Reticulospinal

Answer 10

From reticular formation (pons and medulla)
Medial (pontine)
Lateral (medullary)
Control activity of alpha and gamma neurones - reflex, tone