Question

Describe information processing that occurs with the knee jerk spinal reflex.

Answer 1

• Patellar reflex is an example of monosynaptic reflex.
• When the patellar tendon is just tapped below the knee , the tap initiate an a action potential on a specialized structure known as muscle spindle , which is located within the quadriceps muscle.
• The action potential travel along L3 and L4 nerve root of the spinal cord , via sensory axon or afferent nerve which chemically communicate with a motor nerve by releasing a neurotransmitter called glutamate.
• The result of this motor nerve activity leads to contraction of quadriceps muscle, leading to extension of lower leg that is lower leg kick forward.
• Sensory inputs from quadriceps also activate a interneuron which releases a inhibitory neurotransmitter glycine onto motor neuron of antagonists muscle, that is hamstring muscle causing blocking their stimulation .
• Relaxation of opposing muscle facilitates the extension of lower leg.
• Improper patellar reflex means damage to central nervous system.