DESCENDING PATHWAYS

Question 1

these descending tracts are involved the flexor motor system and fine movement?

Answer 1

corticospinal 
lateral corticospinal 
anterior corticospinal
rubrospinal
tectospinal

Question 2

this descending tract has some control over the perception of pain, runs down the center of the brainstem and is involved with serotonin?

also uncrossed

Answer 2

raphespinal

Question 3

these descending tracts are responsible for the primary extensor musculature, posture and balance and also antigravity muscles?

Answer 3

lateral vestibulospinal
medial vestibulospinal
reticulospinal

Question 4

name this descending pathway?

Primary volitional pathway (Broadmann area 4 and 6)

Begins at corona radiata

Descend through internal capsule and cross cerebri

Becomes lateral and anterior!

2% doesn’t cross!

Answer 4

Corticospinal

Question 5

name this descending pathway?

90% crossed at medullary pyramids

Voluntary skilled motor activity

Greatest control in limb girdles

Comes from primary motor cortex

Answer 5

Lateral Corticospinal

Question 6

name this descending pathway?

8% crossed at anterior white commissure

Passes medulla uncrossed

Greatest control in neck and upper trunk

Answer 6

Anterior Corticospinal

Question 7

name this descending pathway?

Crossed

Coordinates quadrupedal movements (not significant in humans!)

Active in exciting flexor motoneurons

Inhibiting extensor motoneurons

Red nucleus of tengentum of the mid brain crosses to opposite side to contralateral
interneurons and motor neurons of limbs

Answer 7

Rubrospinal

Question 8

name this descending pathway?

Crossed

Reflexive movements of head/neck in response to visual and auditory stimuli (pain too)

Come from tectal superior colliculi of the roof of the midbrain to cervical interneurons and
motor neurons

Answer 8

Tectospinal

Question 9

name this descending pathway?

Uncrossed

Modifies center of gravity to keep balance

Control of extensor motor tone and postural adjustments by antigravity muscles in response
to movement or tilting of head

Nuclei in the medulla to interneurons and motor neurons innervating extensors of trunk and
ipsilateral limbs

Inhibitory input from cerebellum

Excitatory input from vestibular apparatus

Answer 9

Lateral Vestibulospinal

Question 10

name this descending pathway?

Cross and uncrossed

From medial vestibular nucleus

Descends to cervical spinal cord

Adjusts the position of the head in response to changes in posture
(keeps head stable while walking)

Answer 10

Medial Vestibulospinal

Question 11

name this descending pathway?

Uncrossed in pons

Some crossed in medulla

Movement patterns associated with arousal and emotional states

Mediation of motor function

Comes from gigantocellular nucleus

Projects bilaterally as lateral reticulospinal
- Suppresses extensor spinal reflex activity

From medial pontine reticular nuclei

Descends ipsilateral as medial reticulospinal
- Facilitates extensor spinal reflexes

Answer 11

Reticulospinal