Representation of the<unk>  pathway. Striking of the<unk>  tendon with a reflex hammer just below the<unk> stretches the muscle spindle in the quadriceps muscle. This produces a signal which travels back to the spinal cord and synapses (without interneurons) at the level of L3 or L4 in the spinal cord, completely independent of higher centres. From there, an alpha motor neuron conducts an efferent impulse back to the quadriceps femoris muscle, triggering contraction. This contraction, coordinated with the relaxation of the antagonistic flexor hamstring muscle causes the leg to kick. There is a latency of around 18 ms between stretch of the<unk>  tendon and the beginning of contraction of the quadriceps femoris muscle. This is a reflex of proprioception which helps maintain posture and balance, allowing to keep one's balance with little effort or conscious thought. The<unk>  is a clinical and classic example of the monosynaptic reflex arc. There is no interneuron in the pathway leading to contraction of the quadriceps muscle. Instead, the sensory neuron synapses directly on a motor neuron in the spinal cord. However, there is an inhibitory interneuron used to relax the antagonistic hamstring muscle (reciprocal innervation). This test of a basic automatic reflex may be influenced by the patient consciously inhibiting or exaggerating the response; the doctor may use the Jendrassik maneuver in order to ensure a more valid reflex test.
Patellar reflex
Ankle jerk reflex
Plantar reflex
Glabellar reflex
Extensor digitorum reflex
Biceps reflex
Brachioradialis reflex
Jaw jerk reflex