After stroke or spinal cord injury in humans, spastic hypertonia (spastic paralysis) often develops, whereby the stretch reflex in flexor<unk> s of the arms and extensor<unk> s of the legs is overly sensitive. This results in abnormal postures, stiffness and contractures. Hypertonia may be the result of over-sensitivity of alpha motor neurons and interneurons to the Ia and II afferent signals.
Muscle spindle
Efferent nerve fiber
Postganglionic nerve fibers
Nerve plexus
Nerve fascicle
Muscle tissue
Cerebrospinal fibers
Sensory nerve