Motor Tracts Flashcards
What is pathway for corticospinal tract
Cells arise in cortex
descend through posterior limb of internal capsule
passes through cerebral peduncles, anterior pons, pyramids
fibers cross in pyramids of lower medulla
descends in lateral column of SC
synapses with LMNs in spinal cord
Where is the primary motor cortex located
precentral gyrus
What is the function of the medial corticospinal tract
controls postural and proximal movements
What is the difference between medial and lateral corticospinal tract
medial tract doesn’t have fibers crossing in the medulla
What CN are affected by the corticobulbar tract
CN V, VII, IX, X, XI, XII
What is the pathway of the corticobulbar tract
Cortex
descending through genu of internal capsule
cerebral peduncles, anterior pons, pyramids
crosses at pyramids
descends
Where do Medial LMN have a primary function
in axial muscles
Where do Lateral LMNs have a primary function
in limb muscles
Where do LMNs for extensor muscles lie in the SC
ventral
Where do LMNs for flexor muscles lie in the SC
dorsal
What are the medial UMN tracts
Tectospinal
medial reticulospinal
lateral and medial vestibulospinal
What are the lateral UMN tracts
rubrospinal
lateral reticulospinal
Function of Indirect pathways
tonically activate antigravity and axial LMNs
Function of lateral vestibulospinal
facilitation of extension against gravity
Function of medial vestibulospinal
coordination of head movements
function of medial reticulospoinal
facilitation of postural reflexes
Function of rubrospinal
innervate upper limb flexors
Function of lateral reticulospinal
Facilitates flexor motor neurons and inhibits extensor motor neurons
Where does tectospinal tract fibers go
to neck muscles from superior colliculus
Function of tectospinal
coordination of head with eye movements
Characteristics of LMN lesion
flaccid paralysis wasting/atrophy hyporeflexia hypotonia fasciculation
What causes UMN syndrome
loss of corticospinal tract and loss of indirect brainstem motor control pathways
Characteristics of UMN lesion
loss of distal extremity strength and dexterity babinski sign hypertonia spasticity hyperreflexia clasp knife phenomenon
What does rigidity suggest
basal ganglia disease
What does spasticity suggest
UMN lesion
Where are LMN lesions normally located
ipsilateral of lesion
For UMNs, where are lesions located
above lower medulla: contralateral
below/in sc: ipsilateral
What symptoms are associated with complete transection of the spinal cord
all sensation 1/2 lesions below bladder control lost spinal shock (loss of reflexes) UMN signs at levels below lesion LMN signs at level of lesion
Symptoms of hemisection of spinal cord
pain and temp loss from contralateral side
loss of discriminative touch/conscious proprioception on same side
LMN signs at level of lesion
UMN signs ipsilateral of lesion
What is Brown Sequards syndrome
associated symptoms with hemisection of SC
What is syringomyelia
Formation of cysts within spinal cord
What are some symptoms of syringomyelia
Pain and temp affected, motor may also be lost .
Cape/shawl pattern
What is the mechanism of injury to central cord syndrome
cervical hyperextension
What is central seven palsy
lesion of corticobulbar tract involving the 7th CN.
What does a lesion rostral to facial motor nucleus result in
dropping of muscles at the corner of the mouth
What is ALS
destroys only somatic motor neurons
What vascular structure is affected in Wallenberg sign
PICA
What vascular structure is affected in Dejerine syndrome
Anterior spinal a.
What does damage to spinal V nucleus and tract ddo
ipsilateral loss of pain and tempt to teh face
What does inferior cerebellar peduncle damage do
ataxia, known as Wallenberg sign
