Motor Tracts

Question 1

Types of LMN fibers

Answer 1

Gamma - project to intrafusal muscle spindle

Alpha motor - project to extrafusal skeletal m

Question 2

What type of movement does the direct corticospinal tract induce

Answer 2

Voluntary

Question 3

Medial corticospinal tract is for

Answer 3

Postural m

Question 4

Lateral corticospinal tract is for

Answer 4

Limb muscles

Fractionation

Question 5

What part of the internal capsule do the fibers of the direct corticospinal tract travel through

Answer 5

Posterior limb

same as medial corticospinal tract

Question 6

Where does the corticospinal tract decussate

Answer 6

Pyramids of the lower medulla

Question 7

which arteries supply the posterior limb of the IC

Answer 7

lenticulostriate a (off MCA) and anterior choroidal a

Question 8

what does the corticobulbar tract influence

Answer 8

muscles innervated by cranial nerves

NOT eye movements

Question 9

what part of the IC does the corticobulbar tract travel through

Answer 9

the genu of the IC

Question 10

where is the corticobulbar tract located in comparison to the corticospinal tract(s)

Answer 10

medial

Question 11

where are LMNs innervating extensors located in the ventral horn

Answer 11

ventral

Question 12

where are LMNs innervating flexors located in the ventral horn

Answer 12

dorsal

Question 13

what is the purpose of indirect somatic motor pathways

Answer 13

tonically activate antigravity and axial LMNs

keeps a basal rate of firing to maintain a natural tone

Question 14

where are cell bodies located in the tectospinal tract of medial UMN tracts

Answer 14

midbrain, superior colliculus

axons synapse in contralat. ventral horn

Question 15

where are cell bodies located in the medial reticulospinal tract of medial UMN tracts

Answer 15

pons, reticular formation

axons synapse in ipsilat. ventral horn

Question 16

where are cell bodies located in the lateral and medial vestibulospinal tracts of medial UMN tracts

Answer 16

medulla, vestibular nuclei
medial axons synapse in contralat. ventral horn
lateral axons synapse in ipsilat. ventral horn

Question 17

where are cell bodies located in the rubrospinal tract of the lateral UMN tracts

Answer 17

midbrain, red nucleus

axons synapse in contralat. ventral horn

Question 18

where are cell bodies located in the lateral reticulospinal tract of the lateral UMN tracts

Answer 18

medullary reticular formation

axons synapse in ipsilat. ventral horn

Question 19

medial LMNs receive input from

Answer 19

med and lat vestibulospinal
med corticospinal
med reticulospinal
tectospinal

Question 20

lateral LMNs recieve input from

Answer 20

lat corticospinal
lat reticulospinal
rubrospinal

Question 21

what does lateral vestibulospinal tract innervate

Answer 21

ipsilat. LMNs innervating postural m and limb extensors (respond to gravity)

Question 22

what does medial vesibulospinal tract innervate

Answer 22

ipsi and contralat LMNs innervating neck and shoulder ms. (up to T2-T3?)

Question 23

what does medial reticulospinal tract innervate

Answer 23

ipsilat. LMNs innervating postural m and limb extensors (reaction to mvmt and alert?)

Question 24

what does lateral reticulospinal tract innervate

Answer 24

bilat. LMNs fascilitates flexor motor neurons and inhibits extensor motor neurons

Question 25

what does rubrospinal tract innervate

Answer 25

contralat. LMNs innervating upper limb flexors

Question 26

what does tectospinal tract innervate

Answer 26

contralat. LMNs innervating neck m. | turns head to where eyes are looking?

Question 27

LMN lesion signs

Answer 27

``` flaccid paralysis muscle atrophy (chronic) hyporeflexia or areflexia hypotonia denervation hypersensitivity (fasciculations) ```

Question 28

UMN syndrome

Answer 28

loss of corticospinal (direct) tract and loss of regulation from indirect pathway

Question 29

UMN lesion signs

Answer 29

CST: loss of distal extremity strength and dexterity babinski sign hypertonia spasticity - UMN lesion (rate dependent resistance) rigidity - basal ganglia disease (not rate or force dependent) hyperreflexia

Question 30

determining LMN lesion location

Answer 30

clinical signs on same side as lesion

Question 31

determining UMN lesion location

Answer 31

above lower medulla, clinical signs are contralat. to lesion in spinal cord, clinical signs ipsilat. to lesion

Question 32

Decorticate posture

Answer 32

above level of red nucleus (arms make C's)

Question 33

Decerebrate posture

Answer 33

below red nucleus but above reticulospinal and vestibulospinal nuclei

Question 34

Hemisection (brown-sequard syndrome)

Answer 34

pain and temp loss of contralat. side (ALS) ipsilat. discriminative touch, proprioception loss (PCMLS) LMN at lesion UMN ipsilat. lesion ~2 lvl down?

Question 35

syringomyelia | motor tracts ppt

Answer 35

associated with chiari type 1 pain and temp lost first (ALS) motor lost if ventral horn affected UMN lost if lat. CST affected

Question 36

Anterior cord syndrome

Answer 36

compression or damage to anterior portion of spinal cord

Question 37

central cord syndrome

Answer 37

compression and damage to central portion of spinala cord | usually due to cervical hyperextension

Question 38

medial medullary syndrome (dejerine syndrome) what structures affected what vessel could cause this

Answer 38

CN XII nucleas -- lick your wounds medial lemniscus -- (PCMLS) contralat. loss of discriminative touch, propioception, vibratory sense pyramids -- contralat. UMN lesion sx. area supplied by Ant spinal a.

Question 39

lateral medullary syndrome (wallenberg syndrome) what structures affected what vessel could cause this

Answer 39

ALS -- contralat. pain and temp to body trigem. spinal -- ipsilat. pain and temp to face nucleas ambiguus -- CN IX and X vestibular nuclei -- nystagmus, vertigo hypothalamic tract -- ipsilat. horner inf. cerebellar peduncle -- cerebellar ataxia? area supplied by PICA

Question 40

lesions of corticobulbar tract can lead to which types of palsy

Answer 40

central 7 palsy | bell's palsy

Question 41

central 7 palsy

Answer 41

upper facial m. are controlled bilaterally lower facial m. are controlled only by contralat. hemisphere lesion rostral to facial nucleas --> drooping of corner mouth contralat. to lesion

Question 42

bell's palsy

Answer 42

ipsilat. flaccid paralysis of upper and lower face

Question 43

Weber syndrome | structures affected

Answer 43

midbrain CST -- UMN s & sx to UE and LE CB -- central 7 palsy CNIII -- down and out

Question 44

Amyotrophic Lateral Sclerosis (ALS)

Answer 44

destroys only somatic motor neurons | UMNs, brainstem, and sc LMNs