Stretch Reflex (Nursing)

00:00 Now let’s take a closer look at some of the specific reflexes.

00:05 The first reflex is going to be the stretch reflex.

00:09 This causes contraction of a muscle that has been stretched.

00:14 The stretch reflex is going to try to control muscle length.

00:19 Usually a doctor test this reflex using the hammer, the little rubber hammer and he'll hit you on the tendon on the knee.

00:29 Hitting the tendon causes that muscle or that tendon to stretch and therefore stimulates a sensory receptor in the muscle spindle of the knee From there, the sensory neuron is excited and sends a message to the spinal cord.

00:49 So from the spinal cord, the sensory neuron is going to synapse with the motor neuron.

00:55 The stretch reflex is a monosynaptic reflex arc So the sensory neuron directly synapses with the motor neuron and that motor neuron is going to send an impulse to the effector which is the muscle and that muscle will contract.

01:13 At the same time, there is an inhibitory interneuron in the spinal cord as well.

01:21 When this interneuron is going to then send a inhibitory signal to the antagonistic muscle inhibiting that muscle so that it relaxes.

01:33 Thus, the muscle on the top, is going to contract and the muscle on the back is going to relax.

01:40 This causes you to kick your foot up.