Lec 13: Review of Anatomy, Physiology and Motor Exam Flashcards
Where are most of the upper motor neurons located?
precentral gyrus (Brodmann area 4)
What are the tracts connected to the cortical motor neurons?
corticospinal, corticobulbar, corticorubrospinal, corticoreticulospinal, corticovestibulospinal, corticotectospinal
Where are lower motor neurons located in the corticospinal tract?
anterior horn of the spinal cord (composed of alpha motor neurons and projections to muscles)
Where are lower motor neurons located in the corticobulbar tract?
cranial nerve motor nuclei of motor and mixed CNs along with projections to the muscles of the face, head, and neck
Why is denervation atrophy more pronounced in LMN paralysis?
in an UMN paralysis, there is still stimulation from the LMN
What causes spasticity and hyperreflexia in UMN paralysis?
lack of inhibition from the UMNs causes the LMN to function primitively and without inhibition
(T/F) An abnormal EMG-NCV is reflective of both UMN and LMN dysfunction.
F
What are the direct activation pathways?
corticospinal and corticobulbar tracts
What is the function of direct activation pathways?
make muscles move and give strength (gross movement
)
What are the control circuits?
basal ganglia, cerebellum, and thalamus
What are the indirect activation pathways?
rubrospinal, vestibulospinal, reticulospinal, and tectospinal
What is the only part of the body with Betz (giant pyramidal cells) cells?
corticospinal tract
What are the components of the final common pathway?
LMN with muscle that it innervates
What are the different types of movement?
reflex, voluntary movement, rhythmic motor patterns
What is the main neurotransmitter of DAPs?
glutamate
How can you differentiate a supratentorial from an infratentorial lesion based on primary gaze?
supratentorial - towards lesion
infratentorial - away from lesion
Where does decussation occur for the fibers of the corticospinal tract?
medullary pyramids
What is the order of the innervating fibers of the corticospinal tract when passing through the posterior limb of the internal capsule?
leg -> arm -> trunk -> head (lateral to medial)
What is the order of the innervating fibers of the corticospinal tract when passing through the lateral funiculus?
sacral -> lumbar -> thoracic -> cervical (lateral to medial)
Which CNs do not have corticobulbar tracts fibers?
CN I, II, VIII (purely sensory)
Which is more medial? corticospinal or corticobulbar tract fibers?
corticobulbar
How can you differentiate a central facial palsy from a peripheral facial palsy?
CFP - contralateral paralysis of the LOWER half of the face
PFP - ipsilateral hemiparalysis
What is the neurotransmitter used in the final common pathway?
acetylcholine
What are the two types of sensory receptors in muscles?
muscle spindle - conveys stretch sensation
golgi tendon organ - senses muscle tension
What types of afferent fibers regulate the golgi tendon and stretch reflexes?
stretch - IA
GT - IB
