Chapter 2. Prehension

Appendix A - Human Upper Limb Anatomy 35 1
A.2 Skeletal Structure of the Upper Limb
The upper limb skeleton is suspended by muscles to allow for
mobility. Its only skeletal connection with the axial skeleton (in the
trunk) is at the body midline, through the clavicle. The clavicle
articulates with the sternum at its medial, more movable end, and with
the scapula, a free moving structure at its lateral end. Interestingly, the
clavicle is the first bone in the human body to commence ossification
(in about the 5th embryonic week) and among the last bones in the
body for secondary ossifications to be completed (by about 20 - 25
years of age, Camp & Cilley, 1931, cited by Hollinshead, 1982).
Figure A.2 shows the bones and joints of the upper limb skeleton.
The arm consists of the humerus that articulates proximally at the
shoulder with the glenoid fossa of the scapula and distally with the
radius and ulna in the forearm. The hand itself consists of eight carpal
bones, five metacarpals, two phalanges in the thumb, and three
phalanges in each of the four fingers. Figure A.3 provides labels for
the bones and joints in the hand.
A.3 Movement and Degrees of Freedom of Joints
in the Upper Limb
Movement terms are are provided for consistent descriptions of
movements of body segments. The following terms are used to
describe motions in the upper limb. Figure A.4 shows some of these
limb movements.