In this Biopac Student Lab lesson, students become familiar with anatomical and physiological elements of simple spinal reflexes. They will examine properties of some simple neuromuscular reflexes commonly tested in physical diagnosis and measure and compare latent periods and reaction times of extensor and flexor reflexes. Students will elicit an extensor reflex and compare contractile force vs. stimulus strength, apply the Jendrassik maneuver and observe exaggeration of an extensor reflex, then measure and compare reaction times of voluntary activation of skeletal muscle vs. involuntary (reflex) activation of skeletal muscle. http://www.biopac.com/l20-spinal-cord-reflexes
This is an example of the Hoffman's reflex. Pressure is applied over the nail bed of the patient's middle finger using the clinician's fingernail. The clinician then pulls their finger quickly across the nail. A positive reflex is involuntary flexion of any digit and sometimes adduction of the thumb.