Flexion reflex

Flexion reflex is a neural circuit-mediated response to harmful stimuli. It is a withdrawal reflex that functions to remove a body part from potentially damaging events by contraction of the flexor muscles, leading to withdrawal.

Overview

The flexion reflex is a polysynaptic reflex, meaning it involves more than one synapse in the central nervous system. It is a protective motor reflex that is triggered by noxious stimuli such as a painful or harmful event. The reflex involves the rapid contraction of flexor muscles and the simultaneous relaxation of extensor muscles in the same limb, causing the limb to pull away from the harmful stimulus.

Mechanism

The flexion reflex is initiated when nociceptors (pain receptors) in the skin or other tissues are activated by a harmful stimulus. This sends a signal through a sensory neuron to the spinal cord, where it synapses with interneurons. These interneurons then activate motor neurons that control the flexor muscles, causing them to contract and pull the limb away from the harmful stimulus. At the same time, the interneurons inhibit the motor neurons that control the extensor muscles, causing them to relax.

Clinical significance

The flexion reflex is an important part of the body's protective mechanisms. It is often tested in clinical settings to assess the integrity of the spinal cord and peripheral nerves. Abnormalities in the flexion reflex can indicate damage to these structures or to the neural circuits that mediate the reflex.

See also

• Monosynaptic reflex
• Polysynaptic reflex
• Reflex arc
• Nociceptor
• Motor neuron
• Interneuron