The patellar reflex is an example of the<unk> . The<unk>  (myotatic reflex), or more accurately "muscle<unk> ", is a muscle contraction in response to<unk> ing within the muscle. The reflex functions to maintain the muscle at a constant length. The term deep tendon reflex is often used by many health workers and students to refer to this reflex. "Tendons have little to do with the response, other than being responsible for mechanically transmitting the sudden<unk>  from the reflex hammer to the muscle spindle. In addition, some muscles with<unk> es have no tendons (e.g., "jaw jerk" of the masseter muscle)". As an example of a spinal reflex, it results in a fast response that involves an afferent signal into the spinal cord and an efferent signal out to the muscle. The<unk>  can be a monosynaptic reflex which provides automatic regulation of skeletal muscle length, whereby the signal entering the spinal cord arises from a change in muscle length or velocity. It can also include a polysynaptic component, as in the tonic<unk> . When a muscle lengthens, the muscle spindle is<unk> ed and its nerve activity increases. This increases alpha motor neuron activity, causing the muscle fibers to contract and thus resist the<unk> ing. A secondary set of neurons also causes the opposing muscle to relax. Gamma motoneurons regulate how sensitive the<unk>  is by tightening or relaxing the fibers within the spindle. There are several theories as to what may trigger gamma motoneurons to increase the reflex's sensitivity. For example, alpha-gamma co-activation might keep the spindles taut when a muscle is contracted, preserving<unk>  sensitivity even as the muscle fibers become shorter. Otherwise the spindles would become slack and the reflex would cease to function. This reflex has the shortest latency of all spinal reflexes including the Golgi tendon reflex and reflexes mediated by pain and cutaneous receptors.
Stretch reflex
Tonic vibration reflex
Triceps reflex
Tendon reflex
Biceps reflex
Scratch reflex
Red reflex
Jaw jerk reflex