Type II sensory fiber

Type II sensory fiber (group Aβ) is a type of sensory fiber, the second of the two main groups of stretch receptors. They are non-adapting, meaning that even when there is no change in muscle length, they keep responding to stimuli. In the body, Type II fibers are the second most highly myelinated fibers.

The muscle's instantaneous length, or position, is directly proportional to their firing rate. This information would indicate the position of one's leg once it has stopped moving. They do not respond to rate of length changes as do the Ia fibers.

Type II fibers connect to nuclear chain fibers and static nuclear bag fibers, but not to dynamic nuclear bag fibers. These connections, referred to as "flower spray endings" due to their appearance, embed into the poles (ends) of the fibre. It is thought that the relative position of the equatorial regions of the spray when stretched determines the action potential output.