Chapter 2. Prehension

374 Appendices
features of the human hand was its adaptable grip for irregularly
shaped objects, where the palm could arch around the object.
Another palm opposition is seen when objects are held diagonally
in the closed fist, identified by Sollerman (1980) as the diagonal
volar grip and by Cutkosky (1989) as a medium wrap (T). The
thumb sits resting on the radial aspect of the index finger, acting as a
buttress holding the object. The object lies diagonally in the hand.
This is reminiscent of Napier’s power grasp (recall Figure 2.2a).
However, in the power grasp, the thumb pad is usually placed against
the object, the same location seen in the lateral pinch (F). For this
reason, it is classified in Figure B.l as a combination grasp
consisting of the diagonal volar grasp (T) with lateral pinch (F).
Another combination grasp is seen in holding beer mugs, where the
the closed fist cylindrical grasp (B) combines with the lateral pinch
(F) to create the posture that Schlesinger called the ‘cylindrical grasp
with adducted thumb.’
B.1.2 Pad oppositions
When contact is made between the thumb pad and one or more
finger pads, pad opposition is observed. Pad oppositions are based on
five characteristics:
1) the number of fingers used,
2) object shape,
3) size of hand opening (or object size),
4) the finger surfaces making contact, and
5) the flexion/extension state of the fingers.
The opposition between the thumb and one or more finger pads is
posture (D). For simplicity, we are lumping the use of multiple
fingers into one category, although some researchers have chosen to
make this explicit (e.g., Cutkosky, 1989; Kapandji, 1982). Some
researchers have noted the difference in the posture for prismatic
objects (D) and for symmetrical objects (D’). If the researcher did
not make the object shape distinctions, we have classified the pinch
as (D). However, due to the anatomy of the hand, particular
combinations of the fingers are effective in manipulating objects. For
example, when the thumb, middle, and index fingers are used to hold
a rounded object, the three jaw chuck (K) is created (e.g., Cutkosky,
1989; Lister, 1977; Schlesinger, 1919; Skerik et al,. 1971). When
the hand is open wide for a large object and all five fingers are used,