grasp reflex

n.
  1. An involuntary bending of the fingers in response to tactile or tendon stimulation on the palm, producing an uncontrollable grasp, and associated with frontal lobe brain lesions.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.