Motor systems II

Question 1

what is the origin of the corticotectal tract? termination?

Answer 1

1. occipital lobe 2. oculomotor accessory nuclei, superior colliculus (projects to medial longitudinal fasciculus to nuclei of CN 3, 4, 6)

Question 2

what is the origin of the tectospinal tract? termination?

Answer 2

1. superior colliculus 2. C and T spinal cord levels

Question 3

what is the function of the corticotectal / corticospinal tracts?

Answer 3

reflex movement of the eyes, neck (head), and upper thorax in response to auditory, vestibular, and/or cutaneous stimuli

Question 4

how does the rubrospinal tract control movement of the hands and digits?

Answer 4

1. facilitating motor neurons that innervate the digital flexors of the UL 2. inhibiting the motor neurons that innervate the distal extensors of the UL

Question 5

the rubrospinal and reticulospinal tracts consist of what type of neurons?

Answer 5

UMNs

Question 6

the medial (pontine) reticulospinal tract is excitatory to which muscles?

Answer 6

paravertebral and limb extensors

Question 7

what is the effect of the medial (pontine) reticulospinal tract on paravertebral and limb FLEXORS?

Answer 7

inhibitory

Question 8

what is the effect of the lateral (medullary) reticulospinal tract on paravertebral and limb FLEXORS?

Answer 8

excitatory

Question 9

what is the overall function of the medial and lateral reticulospinal tracts?

Answer 9

modulation of muscle tone and posture maintenance

Question 10

what is the function of the medial vestibulospinal tract?

Answer 10

1. maintenance of balance in response to vestibular input 2. control of head movement to keep an image on the retina

Question 11

what is the function of the lateral vestibulospinal tract?

Answer 11

1. excitatory to antigravity muscles (trunk paravertebral and proximal limb extensors) 2. inhibits LMNs that innervate limb flexors

Question 12

what are the descending tracts of the anteromedial group?

Answer 12

1. anterior corticopinal 2. medial and lateral vestibulospinal 3. medial and lateral reticulospinal 4. tectospinal

Question 13

what is the general function of the descending tracts of the anteromedial group?

Answer 13

gross movements of axial trunk and proximal limb to maintain balance as postural adjustments are made

Question 14

what are the descending tracts of the lateral group?

Answer 14

1. lateral corticospinal 2. rubrospinal

Question 15

what is the general function of the descending tracts of the lateral group?

Answer 15

influence movement of distal muscles of limb (fingers)

Question 16

what descending tract makes up the cortical group?

Answer 16

lateral corticospinal (only terminates on lower motor neurons)

Question 17

what is the general function of the descending tract of the cortical group (lateral corticospinal)?

Answer 17

mediate distinct, fractionated movements of the digits (eg typing)

Question 18

what is the arrangement of cell bodies of motor neurons in the ventral horn, from medial to lateral?

Answer 18

TSAFH (trunk, shoulder, arm, forearm, hand)

Question 19

what characterizes Brown-Seguard syndrome?

Answer 19

1. loss of discriminative touch at and below lesion (ipsilateral) 2. loss of pain and temperature 1-3 segments below lesion (contralateral) 3. loss of reflex activity at level of lesion (ipsilateral) 4. UMN signs below level of lesion (ipsilateral) 5. LMN signs at level of lesion (ipsilateral)

Question 20

poliomyelitis affects what part of the spinal cord? what is the result?

Answer 20

1. ventral horns 2. LMN lesion signs

Question 21

combined systems disease is characterized by degeneration of what areas? what are the results?

Answer 21

1. dorsal funiculus - loss of discriminative touch, two point discrimination, vibratory sense, proprioception; sensory ataxia 2. lateral funiculus - UMN signs (Babinski, hyperreflexia, muscle weakness, spasticity)

Question 22

the anterior spinal artery supplies what area of the spinal cord?

Answer 22

anterior 2/3 (anterior and lateral funiculi and gray matter)

Question 23

the posterior spinal artery supplies what area of the spinal cord?

Answer 23

posterior 1/3 (dorsal funiculi and posterior part of dorsal horns)

Question 24

occlusion of the anterior spinal artery could result in what deficits?

Answer 24

1. loss of pain and temperature sensation (anterolateral system) 2. LMN weakness (anterior horn) 3. UMN signs (lateral corticospinal tracts) 4. incontinence (descending pathways)

Question 25

occlusion of the posterior spinal artery could result in what deficits?

Answer 25

loss of proprioception, vibratory sense, discriminative touch (posterior columns)