Coupon Accepted Successfully!


Open Flashcards

Central Nervous System

9 out of 9

Crossed extensor reflex is a

A Withdrawal reflex
B Postural reflex

C Monosynaptic reflex
D Sympathetic

Ans. A Withdrawal reflex

I. Spinal Reflex:

a. Monosynaptic reflex- ~ The simplest reflex arc is one with a single synapse between the afferent and efferent neurons. They are monosynaptic. Eg. stretch reflexes (Knee jerk, ankle jerk etc) ~ Muscle spindle is the receptor for stretch reflex. Q

b. Polysynaptic reflex ~ Reflex are, in which one or more intemeurons are interposed between the afferent and efferent neurons.

Eg.i. Withdrawal reflex Q ii. Abdominal reflex Q iii.Cremastric reflex etc. Q

  1. Withdrawal reflex: ­

a. The withdrawal reflex is a typical polysynaptic reflex Qthat occurs in response to a noxious and usually painful stimulation of the skin or subcutaneous tissues and muscles.

b. The response is flexor muscle contraction and inhibition of extensor muscles.

c. When a strong stimulus applied to a limb, the response includes not only flexion and withdrawal of that limb but also extension of the opposite limb. This is called crossed extension response, which is properly part of the with drawl reflex

  1. Bell-Magendie Law: - in the spinal cord the dorsal roots are sensory and the ventral roots are motor.