LANDERS DESCENDING PATHWAYS

Question 1

basic unit of muscular activity (motor response to a particular sensory output)

Answer 1

reflexes

Question 2

coordination of voluntary motor activity like muscle synergy

Answer 2

cerebellum

Question 3

modulation of motor activity like regulate motor pattern output

Answer 3

basal nuclei

Question 4

origin of volitional motor activity

Answer 4

cerebral (motor) cortex

Question 5

these tracts mediate voluntary and involuntary movement like truncal muscle groups, postural stability in addition to muscle tone, modulation of spinal segmental reflexes and regulation of visceral functions

Answer 5

descending spinal tracts

Question 6

what are the motor cell types of the descending spinal tracts?

Answer 6

upper motoneurons located in the brain and brainstem

lower motoneurons located in the brainstem and the anterior horn of the spinal cord

Question 7

these motoneurons supply extrafusal fibers of the skeletal muscle and directly illicit skeletal muscle contractions

Answer 7

alpha motorneurons

Question 8

these motoneurons supply the intramural fibers of the neuromuscular spindles

Answer 8

gamma motoneurons

Question 9

one alpha motoneurons and all skeletal muscle fibers it innervates?

Answer 9

motor unit

Question 10

what are the four inputs to alpha motoneurons?

Answer 10

Ia afferent fibers from muscle spindles’

Ib afferent fibers from Golgi tendon organs

upper motoneurons

spinal interneurons

Question 11

this is a glycinergic interneurons excited by collateral processes of an excited alpha motoneurons? They act as an off switch by inhibiting the alpha motoneurons which excited them to immediately fire again and this is called=_____?

Answer 11

renshaw interneurons

recurrent inhibition

Question 12

name this reflex?

patellar tendon reflex, knee jerk

muscle spindle

stimulus is stretch of muscle

Ia afferent and Aalpha efferent fibers

extrafusal muscle fiber of the muscle which was stretched

Answer 12

monosynaptic (stretch, myotactic reflex)

Question 13

what is the effect of the myostactic stretch reflexes?

Answer 13

autogenic excitation
-Ia afferents simultaneously excite an interneuron which stimulates an agonist alpha motoneuron

reciprocal inhibition
-at the same time, an interneuron which inhibits the antagonists alpha motoneuron

Question 14

name this reflex?

stimulus is tension on muscle tendon caused by contraction of muscle

afferent fiber is Ib and efferent fiber is the Aalpha of antagonist

effector is the antagonist of muscle contracting

synapse: inhibitory interneuron to alpha motoneuron of muscle contracting; excitatory interneuron to alpha motoneuron of opposing muscle

Answer 14

golgi tendon (inverse stretch, protective)

Question 15

these fibers simultaneously excite an interneuron is inhibitory to the alpha motoneuron of the agonist muscle (autogenic inhibition) while exciting the alpha motoneuron of the antagonist muscle (reciprocal excitation)

Answer 15

Ib fibers

Question 16

name this reflex?

receptors are the free nerve endings for pain

stimulus is pain

afferent fibers are the AIII of C(IV) pain afferents

synapses are multiple, inhibitory interneurons to limb extensors of area being simulated

Answer 16

flexor (withdrawal, flexor crossed-extensor)

Question 17

name the descending pathway tracts that primarily control the flexor motor system and fine movement?

Answer 17

corticospinal tracts both lateral and anterior

rubrospinal tract

tectospinal

Question 18

name the descending pathway tracts which regulate antigravity muscle for posture and balance?

Answer 18

reticulospinal tract
vestibulospinal tract
-lateral
-medial
others:
raphespinal

Question 19

paralysis or paresis
muscle wasting
areflexive
fasciculation’s

what type of motor lesions are these?

Answer 19

lower motor neurons

Question 20

paralysis 
hyperreflexive
clonus
babinski sign
absence of abdominal reflex

what type of motor lesions are these?

Answer 20

upper motor neurons