define motor unit
an alpha motor neuron and the muscle fibers it innervates
phase one of phasic stretch reflex
striking of muscles tendon
phase two of phasic stretch reflex
strike stimulates type 1a afferents from the muscle spindle
phase three of phasic stretch reflex
activity of type 1a afferents causes monosynaptic excitation of alpha motor neurons
phase four of phasic stretch reflex
abrupt contraction of muscle fibers and quick stretch of muscle
medial UMN movements
postural and gross movements
do medial UMN tracts project muscles on contralateral, ispilateral, or both sides of the body
both sides of the body
do lateral UMN tracts project MOSTLY to muscles on contralateral, ispilateral, or both sides of the body
contralateral
What is the motor homunculus?
map of the functional arrangement of neurons in the primary motor cortex
in what region of the cortex does the motor homunculus lie?
primary motor cortex
can stretch reflexes be elicited in people with SCI?
yes
individuals with SCI often exhibit ________-reflexia
hyper
is the (disrupted) lateral corticospinal tract coming from the right or left motor cortex?
right (primary motor cortex)