A fusiform end organ within the skeletal muscle. It is composed of a bundle of 3 to 10 striated muscle fibers (intrafusal fibres) innervated by sensory neurons within a connective tissue sheath. The structure is sensitive to stretch or change in the length of the muscle and is involved in the reflex stretch or the automatic regulation of skeletal muscle length.
It is responsible for the myotatic reflex or stretch reflex of the muscle in which it is enclosed.
- Kuhne’s spindle
- muscle spindle
- stretch receptor