Reflexes

Question 1

Stretch Reflex (Deep Tendon, Myotatic)

Answer 1

Stimulus: Rapid stretch of muscle, excites primary and secondary sensory neurons

Normal response: Stretched muscle contracts, also excites synergist and inhibits antagonist muscles

UMD: Hyperreflexia, Clonus

Question 2

Autogenic Inhibition

Answer 2

Stimulus: Large force on tendon excites GTO

Normal response: Muscle tension decreases; inhibits synergist; excites antagonist muscles

UMD: Clasped Knife reflex - forceful stretch is muscle is first resisted then collapses

Question 3

Flexor Reflex - Protective avoidance reflex

Answer 3

Stimulus: Sharp, painful stimulus - excites cutaneous pain receptors

Normal response: Limb is rapidly withdrawn from stimulus; inhibits extensors of same limb and excites extensors of opposite limb

UMD: Babinski sign - toes extend to cutaneous stimulus of sole of foot

Question 4

Pupillary Light Reflex - II to III

Answer 4

Stimulus: Shine light in eye

Sensory: Optic nerve

Response: Excite constrictor of pupil - III short ciliary nerves

Clinical: Check II, absence can indicate catastrophe

Question 5

Corneal Reflex - V to VII

Answer 5

Stimulus: Touch cornea of eye with cotton

Sensory: Long ciliary nerves (V1), somatic sensory

Response: Close eye (VII branchiomotor)

Clinical: Test for damage to V1 sensory, VII mtor

Question 6

Gag Reflex - IX to X

Answer 6

Test: Touch Posterior tongue, oropharynx

Sensory: Visceral sensory in IX

Response: Excite muscles of pharynx, palate - X branchiomotor

Clinical: Symptoms of X damage - patient says ahh, soft palate not elevated on ipsilateral side, uvula deviated away from lesion

Question 7

Jaw Jerk Reflex (Stretch reflex) - V to V

Answer 7

Stimulus: Tap down on mandible - stretch muscles of mastication

Sensory: Excites muscle spindles in V

Response: Contract muscles that elevate mandible - V3 motor

Clinical: Hyporeflexia indicates V damage