Motor Unit

Question 1

where does the decision for a simple motor act originate

Answer 1

frontal cortical areas

Question 2

which neurons travel in the descending patheays (upper or lower)

Answer 2

upper

Question 3

what are the two types of lower motor nuerons

Answer 3

alpha and gamma

Question 4

what are the features of aplha motor nuerons

Answer 4

large cell bodies, large myelinated axons

branch into numerous termials as approach muscle, attach at nmj

Question 5

definition of a motor unit

Answer 5

a single motor nueron and all the muscle fibres it innervates

Question 6

describe the final common pathway

Answer 6

another term for the activity of lower motor neurons - b/c the last patheay that the NS has control over a muscle

Question 7

role of BN and cerebellum

Answer 7

monitor and adjust activity of descending pathways

- stimulate or inhibit the activity of motor nuclei and the primary motor cortex

Question 8

Name the 3 main descending pathways we focus on

Answer 8

corticospinal

medial

lateral

Question 9

role of the medial descending patheay

Answer 9

control gross movements of the trunk and proximal limb muscles

Question 10

Role of lateral descending pathway

Answer 10

control distal limb muscles that perform more precise movements

Question 11

what layer of the primary motor cortex does the corticospinal pathway originate

Answer 11

pyramidal

Question 12

name the structure near the thalamus that the corticospinal axons travel through

Answer 12

internal capsule

Question 13

what is the pther name for the primary motor cortex

Answer 13

pre-central gyrus

Question 14

name the 3 parts of the corticospinal pathway

Answer 14

corticobulbar

lateral corticospinal

medial corticospinal

Question 15

what cranial nerves does the corticobulbar track synapse on

Answer 15

3-7, 9, 11

and 12 haha

Question 16

role of the corticobulbar tract

Answer 16

conscious confrol of the muscles that move the eye, jaw, face, and some muscles of the neck and pharynx

Question 17

role of umns

Answer 17

generally the lmn have a continuous firing pattern - the umns control this, inhinit the rapid firing, generate tone in the muscle

Question 18

signs of umn leison

Answer 18

abnornal cutaneous reflex
abnormal timing of muscl activation
paresis
hyPERtonia
clasp-knife response

Question 19

signs of lmn leison

Answer 19

loss of reflexes
atrophy
hyPOtonia
fibrilliations (only detected ecg)

Question 20

general role of BN

Answer 20

control of posture and movement

Question 21

name the two classes of movement disorders that BN dysfunction can cause

Answer 21

Hypokinetic (too little movement - e.g. PD),

hyperkinetic (excessive movement e.g. huntingtons, subtypes of cerebral palsy)

Question 22

symptoms of PD

Answer 22

muscular rigity, shuffling gait, droopy posture, muscle tremors and mask-like facial expressions

Question 23

pathology of PD

Answer 23

death of dopamine producing cells in substantia nigra para compacts

loss of dopamine producing cells: reduces activity in motor areas of cerebral cortex, decreasing voluntary movement

Question 24

signs and symptoms of cerbellum dysfunction/ cerebellar disease

think of a drunk person

Answer 24

lack of coordination (ataxia), slurred speech, poorly articulated speech (dysarthia), intention tremor (shaking of limb during voluntary movement)
past pointing (inability yo accurately perform repitious tasks)