Babinski’s sign [Joseph Babinski] , a series of partial responses that are pathognomonic of different degrees of upper motor neuron disease, including (1) absence of an ankle jerk in sciatica; (2) an extensor plantar response, with an extension of the great toe and adduction of the other toes; (3) a more pronounced concentration of the platysma muscle on the unaffected side during blowing or whistling; (4) pronation that occurs when an arm affected by paralysis is placed in supination; and (5) when a patient in a supine position with arms crossed over the chest attempts to assume a sitting position, the thigh on the affected side is flexed, and the heel is raised, while the leg on the unaffected side remains flat.
