I read with interest the posts regarding palmar pressure to elicit sucking.
 The Babkin reflex is, I think, what is being referenced.  This involves a
strong sudden pressure applied with the examiner's thumb on the palms of both
hands simultaneously.  Pressure can be applied to just one palm, but it is
more difficult to elicit a response.  The response is that the mouth opens,
slight elevation of the tongue occurs, the head flexes and rotates to the
midline, the forearm flexes and occasionally the eyes close.  Pressure to one
palm elicits a weaker response with head rotation to the side of the
stimulus.  It can be elicited in preemies as early as 26 weeks gest. weakens
in the first month of life, and disappears by 3-4 months of life.

The response works best if infant is awake.  The intensity of response is
greatest in prematures of a larger weight.  The Babkin reflex"demonstrates
the phylogenetic importance of the functional unity of hand and mouth" in
humans.

Radtka,S. Feeding Reflexes and Neutral Control, in Oral-Motor Function &
Dysfunction in Children, ed. by J. Wilson, Univ. N.C., Chapel Hill, 1977.

Barbara Wilson-Clay, BSE, IBCLC
priv. pract. Austin, Tx