A muscle spindle is a small cluster of specialized muscle fibers within a muscle. Also called stretch receptors, they detect stretch (changes in the length) in the muscle.
The muscle spindle is a type of proprioceptor, which is a sensor in the muscle that identifies the location of your body parts. For example, If you close your eyes and move your arm, you still know where it's located because of proprioceptors.
What It Does
When a muscle stretches, the muscle spindle detects how much and how fast the muscle is stretching and sends signals to the spine with this information.
If your body thinks a muscle is stretching too far or too fast, the muscle spindle's signals trigger the stretch or myotatic reflex. The stretch reflex resists further stretching of the muscle by causing the muscle to contract.
Static and Dynamic
The stretch reflex has two components. The dynamic component lasts for only a moment in response to the initial sudden increase in muscle length. The static component lasts as long as the muscle is being stretched.
The purpose of muscle spindles and the stretch reflex is to help maintain muscle tone and to protect your body from injury caused by overstretching.
- Photo Credit "Practice Makes Perfect (ii)" is Copyrighted by Flickr user: Lin Pernille ♥ Photography (Lin Kristensen) under the Creative Commons Attribution license.
The Structure & Function of Muscle Cells
There are three different types of muscle cells in the human body: skeletal, smooth and cardiac. These are classified as either voluntary...
What Muscles Make You Jump Higher
Whether you're jumping to spike a ball, dunk a basketball or to make a catch in the outfield, the muscles of your...
Definition of a Spindle Cell Tumor
Spindle cell tumors are cancerous masses. They are made up of cells which, when viewed under a microscope have a spindle shape....
What Is a Spindle on a Tire?
Spindles are a component of the suspension system in a vehicle that enables it to drive forward, backward, turn in both directions...
How to Test Deep Tendon Reflexes
According to Kenneth H. Walker, Professor of Medicine and Associate Professor of Neurology at Emory University, a stretch reflex is the “contraction...