Reflexes Flashcards
synonyms for myotatic reflexes
deep tendon reflexes, muscle stretch reflexes, tendon jerks
stretching of intrafusal fibers sends afferent info to the
dorsal horn of spinal corn, stimulates alpha motor neurons
when spinal pathways synapse on the gamma-motor neurons, they influence contraction of the..
muscle spindle, which determines how much contraction happens when the muscle is stretched
these fibers have many mitochondria, extensive capillary blood supply, myoglobin for O2 storage
slow twitch fibers (type I) (distance running)
these fibers have fewer mitochondria, less extensive blood supply, glycogen store and glycolytic enzymes
fast twitch fibers (type IIb) (sprinting)
what determines whether a muscle fiber will be type I or type IIb?
the INNERVATION
a single motor neuron innervating a group of muscle fibers
motor unit
describe motor unit recruitment as used in motor activity
the maximum force developed by a muscle increases exponentially as the percentage of motor units recruited increases and superimposes
describe the pathway in muscle stretch reflex (flexion)
cutaneous afferent fiber enters dorsal horn, synapses, goes to ventral horn, activates motor neuron in the flexor muscle; dorsal horn synapse also goes through ant commissure to contralateral ventral horn to motor neuron to have opposite extensor muscle support
describe the muscle stretch reflex pathway (stretch)
muscle spindle afferent fibers enter dorsal horn, synapse, motor neurons activate the muscle to stretch ;while alpha motor neurons activate the antagonist
reflexes are hyperactive if the lesion is in..
the upper motor neurons
reflexes are hypoactive if the lesion is in the..
lower motor neurons
what type of lesion is characterized by increased muscle tone/spasticity?
upper motor neuron syndrome
what type of lesion is characterized by loss of cutaneous reflexes?
lower motor neuron syndrome and upper motor neuron syndrome
what type of lesion is characterized by Hoffman and Babinski’s sign?
upper motor neuron
