the fingers are withdrawn from an object uncomfortably
hot.
The wrist and hand receive their blood supply
from the radial and ulnar arteries, which
run parallel with the bones concerned, enter
the hand through the flexor "tunnel," and
then join through a double-arch system (Fig.
10). Small branches from the arches serve the
digits. The major venous system comprises
the basilic and cephalic veins superficially
placed on the volar surface of the forearm.
T H E RESTING HAND PATTERN
The resting hand assumes a characteristic
posture, a feature easily seen when the hand
hangs loosely at the side. The resting wrist
takes a mid-position in which, with respect to
the extended forearm axis, it is dorsiflexed
35 deg. (Fig. 11). It is worth noting that this
is the position of greatest prehensile force
(Fig. 12, bottom). The mid-position for radial
or ulnar flexion appears to be such that the
metacarpophalangeal joint center of digit III
lies in the extended sagittal plane of the wrist
(Fig. 11).
Typically, the conformation of fingers and
thumb is similar to that shown for palmar prehension
(Fig. 13), the fingers being more and
more flexed from index to little finger. The relations
between thumb, palm, and fingers are
such as to permit grasp of a 1.75-in. cylinder
crossing the palm at about 45 deg. to the
radioulnar axis. Bunnell (4) considers this "an
ancestral position ready for grasping limbs,
weapons, or other creatures."