motor control

Question 1

what are important CNS regions from control of motor movement?

Answer 1

cerebral cortex, brainstem, spinal cord as well as basal nuclei and cerebellum

Question 2

what is another name for the cortical motor system?

Answer 2

the pyramidal system

Question 3

what is the cortical motor system/pyramidal system made up of?

Answer 3

axons whose nerve cell bodies are located in motor areas of the cortex

Question 4

where are the cell bodies of the cortical motor system/pyramidal system located?

Answer 4

in the pyramidal cell layer of motor areas of the cortex

Question 5

where do the axons of the cortical motor system leave the cortex?

Answer 5

through the caudal limb of the internal capsule

Question 6

where do the axons of the cortical motor system/pyramidal system pass through the midbrain?

Answer 6

the middle 3/5 of the crus cerebri

Question 7

what is the corticobulbar tract?

Answer 7

axons from neurons in the cortex that extend and synapse in the brainstem. these synapse on motor neurons of the cranial nerves

Question 8

what is the corticospinal tract?

Answer 8

it is axons with cell bodies in the cortex that extend from the cortex, through the internal capsule, through the crus cerebri of the midbrain and through the pons and onto the ventral surface of the medulla as the pyramids. the fibers then pass dorsally and decussate to the contralateral side to descend into the dorsal part of the lateral funiculus as the lateral corticospinal tract

Question 9

what is different about ungulates in where the corticospinal tract goes?

Answer 9

in ungulates, most of the fibers of the corticospinal tract end in the cervical cord an interneurons take impulses to the LMN.

Question 10

where does the corticospinal tract end in carnivores:

Answer 10

50% in cervical cord, 20% in thoracic area, 30% below this area

Question 11

where do the corticospinal fibers send collateral branches to?

Answer 11

basal nuclei, thalamus, reticular formation, brainstem nuclei

Question 12

where do the fibers of the corticobulbar tracts travel?

Answer 12

with the corticospinal tracts in then they leave the main pathway via three major branches: peduncular branch to nuclei or cranial nerves III, IV, VI and pontine branchV and the rostral part of the nucleus ambiguus and a bulbopontine branch to the motor nuclei of VII, XII and the caudal part of nucleus ambiguus.

Question 13

what brainstem nuclei project to the spinal cord?

Answer 13

vestibular nuclei (vestibulospinal tract) and numerous nuclei in the reticular formation of the pons and medulla (pontine and medullary reticulospinal tracts)

Question 14

what is the brainstem responsible for (in terms of motor function?)

Answer 14

initiiating and coordinating actions for semiautomatic movements: locomotion, cheewing, maintaining muscle tone, posture

Question 15

what are the basal nuclei?

Answer 15

group of nuclei in telencephalon, diencephalon, rostral midbrain that from subcortical feedback loop; receive input from cerebral cortex and provide input back to cortex

Question 16

what are the 5 structures of the basal nuclei?

Answer 16

caudate nucleus, putamen, globus pallidus, subthalamuc nucleus, substantia nigra

Question 17

what structures of the basal nuclei receive the input from the cortex?

Answer 17

the caudate nucleus and putamen

Question 18

what are the caudate nucleus and putamen together referred to as?

Answer 18

the striatum

Question 19

what are the fibers that goes from the cortex to the caudate nucleus and putamen called?

Answer 19

the corticostriate fibers

Question 20

what are the major output fibers of the basal nculei?

Answer 20

substantia nigra and portions of globus pallidus that give feedback to cortex via the thalamus

Question 21

do the basal nuclei have projections to the brainstem?

Answer 21

relatively few

Question 22

do the basal nuclei have a direct influence on movement?

Answer 22

no that act through corticospinal and brainstem spinal projections

Question 23

what are signs caused by lesions of CNS motor centers and pathways?

Answer 23

1. paralysis or paresis
2. local reflexes present but possibly altered
3. appearance of abnormal reflexes
4. disuse atrophy

Question 24

what is the difference between the pyramidal and extrapyramidal systems?

Answer 24

the pyramidal system has to do with the neurons whose axons connect directly to motor neurons in the spinal cord. clinically, extrapyramidal system has to do with the basal nuclei

Question 25

what are extrapyramidal signs of lesion?

Answer 25

involuntary movements or rigidity without paralysis

Question 26

what are the three major regions which are directly involved in initiation of movement?

Answer 26

the spinal cord, brainstem and the cerebral cortex

Question 27

what are the two important structures that regulate output from the brainstem and cerebral cortex

Answer 27

cerebellum and the basal nuclei

Question 28

what distinguishes voluntary movements from reflexive movements?

Answer 28

voluntary movements they are purposeful and do not necessarily have to be evoked by external stimuli

Question 29

why can lesions that disrupt the brainstem affect muscle tone?

Answer 29

they may disrupt the brainstem lesions such as the vestibular nuclei and nuclei of the pontine reticular formation as well as the red nucleus. these centres tend to facilitate postural muscles