Pathways (test 2)

Question 1

What is the function of the anterior corticospinal pathway? Describe the pathway

Answer 1

Function:
Motor for axial muscles

Pathway:
UMNs originate at the precentral gyrus → corona radiata → posterior limb of the internal capsule → brainstem via the cerebral peduncle → through the pons → medullary pyramids → down the anterior corticospinal tract of the spinal cord → decussate at the level of the LMN → synapse onto LMNs in the medial regions of the ventral horn of the spinal cord

Question 2

What is the function of the lateral corticospinal pathway? Describe the pathway

Answer 2

Function:
Motor for limb muscles

Pathway:
UMNs originate at the precentral gyrus → corona radiata → posterior limb of the internal capsule → brainstem via the cerebral peduncle → through the pons → medullary pyramids → decussate at the pyramidal decussation → down the lateral funiculus of the spinal cord → synapse onto LMNs in the lateral regions of the ventral horn of the spinal cord

Question 3

What is the function of the corticobulbar pathway? Describe the pathway

Answer 3

Function:
Path from UMNs to cranial nerve motor nuclei

Pathway:
Primary motor cortex → genu of the internal capsule → brainstem via cerebral peduncle → various CN motor nuclei BILATERALLY except for nuclei for lower facial muscles and hypoglossal to genioglossus

Question 4

What is the function of the rubrospinal pathway? Describe the pathway

Answer 4

Function:
Provides control of the contralateral limbs (innervation of flexors)

Pathway:
UMN originates in the red nucleus → decussates immediately in the ventral tegmentum → anterior horn in cervical spine to flexor LMNs

Question 5

What is the function of the vestibulospinal pathway? Describe the pathway

Answer 5

Function:
Control of head movement in response to vestibular stimulation; bilateral

Pathway:
Vestibular system → vestibular nuclei in pons → medial and lateral vestibulospinal tracts → LMN in anterior horn → postural muscles (head, neck, and trunk)

Question 6

What is the function of the reticulospinal pathway? Describe the pathway

Answer 6

Function:
Provide ipsilateral control of antigravity muscles (upper body flexors and lower body extensors) and muscles involved in locomotion

Pathway:
Reticular formation in the pons or medulla → descend pontine or medullary reticular formation → synapse on LMNs in the spinal cord

Question 7

What is the function of the tectospinal pathway (aka colliculospinal pathway)? Describe the pathway

Answer 7

Function:
Involved in startle reflexes

Pathway:
UMN originate in tectum → decussate immediately → descend down the tectospinal tract → innervate LMNs at spinal levels

Question 8

Describe the pathway discriminative touch in the face

Answer 8

sensory nerves of the trigeminal CN –> chief sensory nucleus in the pons –> synapse and decussate –> travel to the cortex

Question 9

Describe the pathway pain and temperature in the face

Answer 9

sensory neurons of the trigeminal CN –> enter the pons –> descend to the medulla –> synapse and decussate at the spinal nucleus of CN V –> ascend to the cortex and insula

Question 10

What tracts belong to the lateral motor system?

Answer 10

anterior corticospinal

lateral corticospinal

corticobulbar

rubrospinal

Question 11

What tracts belong to the medial motor system?

Answer 11

vestibulospinal

reticulospinal

tectospinal (colliculospinal)

Question 12

Describe facial motor innervation

Answer 12

lower face is innervated contralaterally by the cortex

upper face is innervated bilaterally by the cingulate gyrus

Question 13

Describe innervation of the tongue (CN XII)

Answer 13

the tongue is innervated contralaterally by the cortex

Question 14

Where do corticospinal and corticobulbar tracts run in the internal capsule?

Answer 14

corticospinal (posterior)

corticobulbar (genu)

Question 15

Might need to know this

Answer 15

got it?