Spinal reflexes (dave's notes)

Question 1

What is the simples spinal reflex? Why?

Answer 1

Stretch reflexes - because they are monosynaptic

Question 2

Give the seven steps of a stretch reflex

Answer 2

Stretches spindle
Stimulates afferent fibres
to spinal cord via the posterior root
synapses directly with alpha motor neurons 
axons form the efferent side of the arc
causes extrafusal fibres to contract
Jerk

Question 3

What does diminution or absence of a spinal reflex indicate?

Answer 3

Interruption or muscular defect

Question 4

What does exaggeration of a spinal reflex indicate?

Answer 4

Upper motor neuron lesion due to decreased control

Question 5

What superficial skin reflexes are multi synaptic?

Answer 5

Plantar
Abdominal
Anal
Bulbocavernosus

Question 6

What is the plantar reflex?

Answer 6

Stroking normally causes plantarflexion of the great toe

Question 7

What is the abdominal reflex?

Answer 7

Light stroking across the anterior abdominal wall causes contraction of the underlying muscles

Question 8

What is the anal reflex?

Answer 8

Contraction of the external anal sphincter following pinprick of the perianal skin

Question 9

What is the bulbocavernosus reflex?

Answer 9

Contraction of the sphincter (PR) on squeezing the glans penis