Cortex & Movement

Question 1

What are the predominate neurotransmitters for LMN and UMN?

Answer 1

LMN: ACh
UMN: glutamate

Question 2

What are the major cortical UMN tracts?

Answer 2

Corticospinal to spinal nerve LMN, corticobulbar to cranial nerve LMN

Question 3

What are the brainstem UMNs?

Answer 3

Eye movement: sup colliculus vergence center

Vestibular nuclei, red nucleus, reticular formation nuclei

Question 4

What are the 2 cortical UMN areas?

Answer 4

Primary motor cortex for focal m contractions, and premotor cortex for planning/sequencing of patterned movements

Question 5

Describe modulation of the primary motor cortex.

Answer 5

Premotor cortex to plan, somatosensory cortex to integrate, thalamus VPM/VPL somatosensory and VL/VA motor

Question 6

What is motor apraxia?

Answer 6

Lesion to premotor cortex or parietal lobe, inability to perform a planned movement w/o paralysis or ataxia

Question 7

What are the neurons of empathy?

Answer 7

Mirror neurons in premotor cortex

Question 8

What are the 2 modulators of motor thalamus?

Answer 8

Basal nuclei (internal globus pallid us, ipsilateral) and pontocerebellum (coordinating intended movement; contralateral)

Question 9

What are the locations and functions of lateral and medial premotor cortex?

Answer 9

Lat: planning/sequencing of grasping movements, front precentral gyrus, visual/verbal guide
Med: supp motor area, planning/sequencing of complex movements, bilateral effects, post-medial part sup frontal gyrus

Question 10

Where does corticobulbar tract project?

Answer 10

Non-ocular CN LMNs bilaterally. There are no cortical UMN projections to ocular CN motor nuclei.

Question 11

What are symptoms of unilateral UMN lesions?

Answer 11

Little effect on LMN of CN 5, 9, 10, 12. For 7: paralysis of contra lower face, forehead spared

Question 12

What are LMN signs?

Answer 12

Ipsilateral deficit, atonia, atrophy, areflexia, fasciculations

Question 13

What are UMN signs?

Answer 13

Positive: spasticity, clasped knife, hyperreflexia, Babinski, clonus, pronator drift, no muscle wasting
Negative: weakness/paralysis, loss of dexterity

Question 14

What is the underlying cause of spasticity?

Answer 14

Exaggerated m spindle stretch reflexes because of abnormal alpha-gamma activation

Question 15

What are three proposed mechanisms leading to spasticity?

Answer 15

Loss gamma/alpha neuron inhibition, unopposed action certain brainstem pathways, maladaptive remodeling in cord or brain

Question 16

What is the lentiform nucleus?

Answer 16

Putamen and globus pallidus

Question 17

Where in the posterior limb internal capsule are corticobulbar, corticospinal, and thalamocortical fibers located?

Answer 17

Bulb: near genu
Spine: posteriorly
TC: face near genu, body posteriorly

Question 18

What part of the crus cerebra is corticospinal and corticobulbar tracts? What’s in the other parts?

Answer 18

Middle 3/5
Anterior 1/5: corticopontine fibers from anterior cortex
Posterior/lateral 1/5: corticopontine from posterior cortex

Question 19

What are the three types of brainstem lesions that affect corticospinal and specific CNs? What are these called? What are the symptoms?

Answer 19

Alternating hemiplegias: corticospinal tract and CN 3 (midbrain lesion), CST and CN 6 (pontine), CST and CN 12 (medulla)
Symp: LMN lesion on 1 side, UMN on alternate side

Question 20

What is affected by lenticulostriate lacunar capsular stroke?

Answer 20

Internal capsule, caudate, putamen, globus pallidus

Question 21

What are symptoms of lesion to posterior limb internal capsule?

Answer 21

Contralateral spastic paralysis and loss of conscious somatosensation of body, lower contra face paralysis, contra loss conscious somatosensation face