Muscle spindle
Videos
Muscle spindles are stretch receptors within the body of a skeletal muscle that primarily detect changes in the length of the muscle. They convey length information to the central nervous system via a
Mammalian muscle spindle showing typical position in a muscle (left), neuronal connections in spinal cord (middle) and expanded schematic (right). The spindle is a stretch receptor with its own motor supply consisting of several intrafusal muscle fibres. The sensory endings of a primary (group Ia) afferent and a secondary (group II) afferent coil around the non-contractile central portions of the intrafusal fibres. Gamma motor neurons activate the intrafusal muscle fibres, changing the resting firing rate and stretch-sensitivity of the afferents.
Light microscope photograph of a muscle spindle with H&E stain
schematic of fusimotor action
Proprioception
Videos
Proprioception is the sense of self-movement, force, and body position.
Muscle spindle
…the muscle. They convey length information to the central nervous system via afferent nerve fibers. This information can be processed by the brain as proprioception. The responses of muscle spindles to changes in length also play an important role in regulating the contraction of muscles, for example, by activating…
Schematics and images of types of limb proprioceptor neurons in mammals (top) and insects (bottom)