Question

Highlight 3 different kinds of reflex’s, going from simple to more complex based reflexes. What makes them simple or more complex, what “triggers” them and what is the resultant action/movements produced?

Answer 1

Answer. Generally there are 3 reflexes based on the location of receptors:

a). Superficial reflex examples, plantar and corneal reflex

b).Deep reflex examples, jaw and knee jerk

c). Visceral reflex , examples, voiding reflex, defecation reflex etc.

Reflex can also be classified as based on the number of neurons involved in the reflex arc:

a). Monosynaptic reflex example, sensory neuron, afferent fiber, motor neuron, efferent fiber, effector organ, stretch reflex. Tapping of muscle tendon brings about the stretching of the extrafusal fibers

b). Polysynaptic reflex example, sensory neuron, afferent fiber, interneuron, motor neuron, efferent fiber, effector organ. Inverse stretch reflex. In this kind of reflex the golgi end apparatus (receptor in tendon), the contraction occurs while muslce is in isometric contractile state i.e the length of the muscle remains same while contraction increases gradually. This tend to snap the tendon in reflex action relaxes the muscle in order to protect the muscle. This is an example of autogeni inhibition.

Clinical significance of reflex can be used to distinguish between lower motor and upper motor neuron lesions. As in uppper motor lesion, all superficial reflexes are lost barring plantar reflex which is babinski positive with exaggerated deep reflexes wherein there is loss of both deep and superficial reflexes.

Plantar reflexes: When toe of foot is stroked and continued untill area underlying the toes there is plantar flexion of all the fingers along with toe.

Babinski positive sign: There is fanning of all the foot fingers and toe dorsiflexion. This is particularly seen in upper motor neuron lesion.