Library · Physiology
Reflex arc
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A typical reflex arc is the complete circuit that makes the body respond without you deciding anything. It has these parts: an afferent neuron, the one that brings information in from the periphery and is usually sensory; an efferent neuron, the one that carries the command back out and is usually motor; and one or more interneurons, the ones that connect them to each other.
When the arc is spinal, its parts are arranged in two limbs: the afferent one, which enters the spinal cord, the cord of nerve tissue that runs inside the spine, and the efferent one, which leaves it, with one or more interneurons between the two. It is a doorbell with its own wire between the button and the bell.
The simplest spinal reflex is the monosynaptic one, the kind that needs only a single connection, and the myotatic reflex, also called the stretch reflex, is one of those. It begins when the muscle is stretched suddenly, and among its structures is the muscle spindle, a sensor tucked inside the muscle itself.
In brief
A typical reflex arc consists of an afferent neuron, usually sensory, an efferent neuron, usually motor, and one or more interneurons that connect them.
In the spinal reflex arc these parts are arranged in two limbs, afferent and efferent, with one or more interneurons between them.
A doorbell with its own wire between the button and the bell.
The simplest spinal reflex is monosynaptic, and the myotatic reflex is one: it arises from sudden stretching of the muscle, and the muscle spindle is among its structures.
Sources (2)
- National Center for Biotechnology Information, StatPearls PublishingNeuroanatomy, Spinal Cord Myotatic Reflex, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingNeuroanatomy, Somatic Nervous System, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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