Plantar Reflex

PLANTAR REFLEX (planter) is obtained by irritating the sole with a stroking stimulus (usually with the handle of a percussion hammer) and is manifested by plantar flexion of the toes, dorsal flexion of the foot, flexion of the calf, and flexion of the thigh. In the normal state, the reflex has a rapid tempo and is essentially different from pathological protective reflexes, which are characterized by slowness of the reflex movement. The volume of the reflex is very different individually and in the normal state: in some cases it is limited only to flexion of the toes, in others, after irritation of the sole, there follows vigorous withdrawal of the entire lower limb. The reflex arc of the P. r. corresponds to Lv-Si-и. With a violation in the area of these segments or the corresponding roots or peripheral nerves, the P. r. fades. With a lesion of the pyramidal tract, the P. r. undergoes a typical change: instead of the usual plantar flexion of the toes, irritation of the sole gives dorsal extension of the big toe and a fan-like divergence of the others (see Babinski reflex)—the most important sign of a lesion of the pyramidal tract.