neuromusc II midterm 2

what are the motor control centers of the brain

motor cortex

cerebellum

basal ganglia

how does the motor cortex connect to the basal ganglia

ipsilaterally

how does the motor cortex connect to the cerebellum

contralaterally

what does the afferent input to the motor cortex relay through

the somatomotor relay nuclei of the thalamus (VA and VL)

how does a basal ganglia lesion present

motor dysfunction contralaterally

how does a cerebellum lesion present

motor dysfunction ipsilaterally

how do the basal ganglia and cerebellum influence motor function

via connections with areas from which UMNs originate

where is the motor cortex located

in the posterior portion of the frontal lobe

what are the components of the motor cortex

primary motor and motor association regions

where is the primary motor cortex located

precentral gyrus

where is the motor association cortex located

anterior to primary motor cortex

where is the premotor portion of the motor association cortex located

lateral aspect of frontal lobe

where is the supplemental motor portion of the motor association cortex located

medial aspect of fronta lobe

what is the final site for cortical processing of motor commands and is involved in execution of motor commands

primary motor cortex

what is the function of the motor association cortex

motor planning

what are additional motor cortical areas

broca's area (expressive language)

frontal eye fields (eye movements)

what vascularizes the motor cortex

branches of the internal carotid artery

what vascularizes the medial aspect of the motor cortex (lower extremity)

anterior cerebral artery

what vascularizes the lateral aspect of the motor cortex (upper extremity and face)

middle cerebral artery

what is the effect of anterior cerebral artery stroke

lower extremity weakness and UMN signs contralaterally

how do middle cerebral artery strokes present

face and upper extremity weakness and associated UMN signs contralaterally

where are UMNs located

entirely in the CNS

what do UMN lesion signs indicate

CNS lesion

where are LMNs located

in both the CNS and PNS

what do LMN lesion signs indicate

either CNS or PNS lesion

where do UMNs originate

motor cortex

brainstem motor nuclei

what UMNs originate from the motor cortex

corticospinal tract

corticobulbar tract

what UMNs originate from the brainstem

rubrospinal

reitculopsinal

vestibulospinal

tectospinal

which UMN tracts are pyramidal

corticospinal and corticobulbar

which UMN tracts are extrapyramidal

rubrospinal

reitculopsinal

vestibulospinal

tectospinal

what are pyramidal tracts

they pass through the pyramids of the medulla

which UMN tracts are direct activating systems

corticospinal

corticobulbar

which UMN tracts are indirect activating systems

rubrospinal

reitculopsinal

vestibulospinal

tectospinal

what are direct activating systems

arise from the motor cortex

what are the indirect activating systems

arise from the brainstem

what are the UMNs that originate in the motor cortex and descend to innervate LMNs in the spinal cord

corticospinal tract

what are the UMNs that originate in the motor cortex and descend to innervate LMNs in the brainstem

corticobulbar tract

what innervates the upper part of the facial nucleus

the corticobulbar fibers from both sides of the motor cortex

how is the lower part of the facial nucleus innervated

only by crossed corticobulbar fibers

what does lesion of corticobulbar fibers from one side of the motor cortex result in

facial weakness in the lower half of contralateral face

how do LMN vs UMN lesions affect facial weakness

-UMN causes contralateral lower half of face weakness

-LMN causes ipsilateral entire face weakness

what makes up the lateral motor system of the spinal cord

lateral corticospinal tract

rubrospinal tract

what makes up the medial motor system of the spinal cord

anterior corticospinal tract

vestibulospinal tract

reticulospinal tract

tectospinal tract

what determines the function of the lateral and medial motor system

-synaptic connections within the ventral horns of the spinal cord

-somatotopic organization of the ventral horn

where do the tracts of the lateral motor system synpase

into the more lateral and posterior portion of the ventral horns

where do the tracts of the medial motor system of the spinal cord synapse

synapse into the more anterior and medial portions of the ventral horns

where do LMNs of the lateral motor system innervate

more laterally placed muscles in the limbs

flexors

what do LMNs of the medial motor system innervate

more medially placed muscles in the trunk

extensors

what are important functions of the medial motor system

-control of trunk and proximal limb extensor musculature

-control of balance and posture

what controls the intrinsic muscles of the spinal column

medial motor system especially vestibulospinal tracts

is control of the limbs from ipsilateral or contralateral motor cortex

contralateral

is UMN control of postural musculature bilateral or unilateral

bilateral

what percent of the corticospinal tract fibers decussate and descend in the lateral column to form the lateral corticospinal tract

80-90%

where does the rubrospinal tract originate

red nucleus of the midbrain

where does the rubrospinal tract decussate

midbrain

where does the rubrospinal tract descend to

only to the cervical cord

where does the vestibulospinal tract orginate

vestibular nuclei in brainstem

what input does the vestibular nuclei receive

input concerning head position and movement from the vestibular receptors in the inner ear

what do ascending projections of the vestibulospinal tract form

medial longitudinal fasciculus

what does the medial longitudinal fasciculus ascend to innervate

CNs III, IV, VI

which tract is concerned wtih maintenance of balance

vestibulospinal

what is the function of the medial longitudinal fasciculus

coordination of head and eye movement (movement of the eyes that compensate for head movement and different head positions

where does the tectospinal tract originate

in the superior colliculi in tectum of midbrain

where does the tectospinal tract decussate

midbrain

what is the function of the tectopsinal tract

reflex head turning in response to visual and auditory stimuli

where does the reticulospinal tract originate

reticular formation of brainstem

are reticulospinal projections crossed or uncrossed

both

where are LMN cell bodies located

brainstem motor nuclei and ventral horns of the spinal cord

what is a motor unit

LMN and all the muscle fibers it innervates

what fibers do LMNs innervate

extrafusal and small intrafusal muscle fibers

what are the LMNs that innervate extrafusal muscle fibers called

alpha motor neurons

what is the function of alpha motor neurons

contraction of the skeletal muscle both voluntary and reflexive

what are LMNs that innervate small intrafusal muscle fibers called

gamma motor neurons

what is the function of gamma motor neurons

sensitivity of the muscle spindle stretch receptor

what is associated with greater gamma motor neuron firing

greater sensitivity of muscle spindle stretch receptors

2+ and 3+ DTRs

what is associated with lesser gamma motor neuron firing

lesser sensitivity of muscel spindle stretch receptor

1+, 1+(R), 0(R) DTRs

what does the trochlear nerve innervate

the contralateral superior oblique muscle

what is the myotome of C5

deltoid

what is the myotome for C6

biceps and wrist extensors

what is the myotome of C7

triceps, wrist flexors and finger extensors

what is the myotome of C8

finger flexors

what is the myotome of T1

interossei

what is the myotome of L1-3

psoas

what is the myotome of L2-4

quads and adductors

what is the myotome of L4

anterior tibialis

what is the myotome of L5

dorsiflexors, extensor hallicus longus

what is the myotome of S1

plantarflexors, evertors

what is the innervation of the axillary nerve

deltoid and teres minor

what is the innervation of the radial nerve

triceps, brachioradialis, supinator, wrist extensors, finger extensors

what is the innervation of the musculocutaneous nerve

coracobrachialis, biceps

what is the innervation of the median nerve

pronator teres and quadratus, flexor carpi radialis, flexor digitorum, thenar muscles

what is the innervation of hte ulnar nerve

flexor carpi ulnaris, flexor digitorum, hypothenar muscles

what is the innervation of the femoral nerve

quads, iliacus, sartorius, pectineus

what is the innervation of the obturator nerve

adductors of the hip

what is the innervation of the common peroneal

anterior tibialis, toe extensors, evertors

what is the innervation of the tibial nerve

gastroc-soleus, posterior tibialis, toe flexors, and intrsinsic muscles of the foot

what is the innervation of the superior gluteal nerve

gluteus medius

what is the innervation of the inferior gluteal nerve

gluteus maximus

what is weakness a common characteristic of

UMN lesions, LMN lesions, NMJ disease, muscle disease

what are UMN lesion signs

hyperflexia

pathological reflexes