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 they keep responding even when the muscle has stopped changing its length. They are the second most highly myelinated fibers in the body.
Their firing rate is directly related to the muscle's instantaneous length, or position. 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, but not to 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.
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