Motor Tracts Flashcards
Where are the cell bodies of the UMNs located?
Cerebral cortex or brainstem
What type of motor neurons are the cranial and peripheral nerves?
LMNs
Fibers traveling through the medial corticospinal tract innervate what muscles?
Postural muscles
Fibers traveling through the lateral corticospinal tract innervate what muscles?
Limb muscles
Voluntary motor action is associated with what tract?
Corticospinal
Fractionation of movement is associated with what tract?
Lateral corticospinal tract
What horn do the UMNs and LMNs of the corticospinal tract synapse?
Ventral
What part of the internal capsule do the cell bodies of the corticospinal tract travel through?
Posterior limb
Lesion in the median corticospinal tract would affect what structures? On what side?
Ipsilateral postural muscles
What are the cranial nerves are influenced by the corticobulbar tract?
5, 7, 9, 10, 11, 12
What part of the internal capsule does the corticobulbar tract travel through?
Genu
What is the relationship between the corticobulbar and corticospinal tracts?
Corticobulbar travels medially to corticospinal
If CN IX is being influenced by the corticobulbar tract, what side is being affected?
Ipsilateral
What muscles do the medial LMNs in the ventral horn innervate? Lateral?
Medial project to axial muscles
Lateral project to limbs
What tracts do the medial LMNs receive input from?
Tectospinal
Medial vestibulospinal
Medial reticulospinal
Medial corticospinal
Lateral vestibulospinal
What tracts do lateral LMNs receive input from?
Rubrospinal
Lateral reticulospinal
Lateral corticospinal
Which vestibulospinal tract goes to all spinal levels? What side does it innervate?
Lateral Vestibulospinal tract
Ipsilateral
Where do the medial vestibulospinal fibers terminate?
T2 to T3
(innervate neck and shoulder muscles)
Which reticulospinal tract innervates postural muscles and limb extensors? What side?
Medial reticulospinal (pontine)
Ipsilateral
What neurons do the lateral (medullary) reticulospinal tract facilitate and inhibit?
Facilitates flexor motor neurons
Inhibits extensor motor neurons
What does the rubrospinal tract innervate?
Upper limb flexors
What tract is involved with visual reflexes to auditory stimuli?
Tectospinal
Patient presenting with flaccid paralysis, muscle atrophy, hyporeflexia, and hypotonia or fasciculations probably has a lesion where?
Lower motor neurons
What tract is lost in UMN syndrome?
Corticospinal tract (direct)
Loss of regulation from indirect pathway
In an UMN lesion, what is overactive and what is underactive?
Overactive: Muscles - hypertonic, spastic (collapse of resistance at end of ROM), hyperreflexia
Underactive: distal extremity strength
What side and level would LMN lesion signs manifest?
Ipsilateral at the level of the lesion
Where would a UMN lesion have contralateral and ipsilateral clinical signs?
Contralateral - Above lower medulla (where corticospinal tract crosses)
Ipsilateral - Spinal cord
If UMN is lesioned, where do the clinical signs manifest?
Below level of lesion
If a patient has decorticate posturing, where is the lesion?
Above the level of the red nucleus (UMN)
In decerebrate posturing, what nuclei is the lesion located between?
Below red nucleus, above reticulospinal and vestibulospinal
After suffering an injury to the spinal cord, a patient initially shows +1/4 DTRs. After a period of a couple weeks, pt shows +4/4 DTRs. What disorder does he have? What has been lesioned?
Spinal shock
Corticospinal tract (appears as a UMN lesion)
Patient presents with hemiparaplegia on the ipsilateral side and hemianesthesia on the contralateral side. What syndrome is this and what has been lesioned?
Brown Sequard’s Syndrome
UMN of the CST, Dorsal column, spinothalamic tract
In a syringomyelia, what is affected if that pt has LMN signs?
Ventral horns
In a syringomyelia, what is affected if that pt has UMN signs?
Lateral corticospinal tract
Patient with ipsilateral flaccid paralysis and hyperreflexia, contralateral loss of pain and temperature sensation. However, vibratory sense is intact. You suspect that the anterior spinal artery has been hit. What syndrome is this?
Anterior cord syndrome
Patient presents after MVC where he was rear-ended. Pt states he doesn’t have a headrest and his head “flew back”. The patient complains of loss of motion in the arms and hands. What syndrome might he ahve?
Central cord syndrome
What structures are lost in lateral medullary syndrome?
Spinothalamic tract (ALS)
Spinal trigeminal nucleus/tract
Nucleus ambiguus
vestibular nuclei
Inferior cerebellar peduncle
Dejerine syndrome can be brought on by occlusion of what artery?
Anterior spinal A.
What structures are lost in medial medullary/Dejerine syndrome?
Pyramids
Medial lemniscus
CN 12 nucleus
What tract is lesioned in central 7 palsy? What nucleus?
Corticobulbar tract
Lower facial motor nucleus
Where is the lesion in Weber Syndrome? What structures are affected?
Pons
Corticospinal tract
Corticobulbar tract
CN 3
What neurons are affected in amyotrophic lateral sclerosis?
Somatic motor neurons (both UMNs and brainstem/SC LMNs)
Progressive loss of sensory and motor function in the hands and feet towards the body may be a sign of what disorder?
Polyneuropathy
Patient presents with ataxia, vertigo, loss of pain/temp to the R face but loss of pain/temp to the L arm. What syndrome is this patient suspicious for? What artery may be occluded?
Lateral Medullary/Wallenberg’s syndrome
PICA
Pt presents with R sided loss of proprioception, vibratory loss, as well as R arm flaccid paralysis. Also presents with L tongue deviation. What is this patient suspicious for?
Medial medullary/Dejerine syndrome
Pt presents with R lower face droop, flaccid paralysis of the R arm, as well as R tongue deviation and L uvula deviation. Upon eye examination their R eye is dilated. What syndrome might this patient have?
Weber
