Lecture 7: Reflexes, Muscle Tone, and Peripheral Nerve Injury

reflex arc have _______ components

sensory and motor

components of a reflex arc

• sensory receptor

• sensory neuron

• interneuron(s)

• motor neuron

• effector

muscle spindle receptors detect

muscle stretch

golgi tendon organ receptor detects

tension (force of contraction)

muscle spindle and golgi tendon organ both signal the

CNS

muscle spindle receptor structure

• lie between muscle cells in the muscles

• has both sensory and motor parts

muscle spindle receptor function

muscle stretch also stretches muscle spindle, activating sensory neuron that sends signals to the CNS (proprioception)

the myotatic reflex is the

stretch reflex

the withdrawal reflex is stimulated by

pain receptors

the crossed-extensor reflex helps us

maintain balance during the withdrawal reflex

reflexes are the key to

muscle tone

damage to a cutaneous nerve affects

sensation and blood flow to skin

damage to a motor nerve affects

muscle function

paresthesia

damage to sensory axons from skin

effects of damaging one motor axon

• motor unit atrophy

• muscle weakness (paresis)

effects of multiple motor axons damaged

reflexes diminished (hyporeflexia)

effects of all motor axons in a nerve to a muscle damaged

• muscle is paralyzed'

• no reflexes (areflexia)

damage anywhere along the length of the axon interrupts

signalling

common nerve compression syndromes

• carpal tunnel

• ulnar nerve compression

neuropathy

can cause a tingling or burning sensation, numbness, sensitivity, and even sharp/jabbing pain