The scapular portion is a slightly curved oblong plate; its proximal third the scapula (fig. 22, 1) is ossified and bounds part of the well-marked glenoid cavity (fig. 22, 4); its distal portion forms a large oblong cartilaginous plate, the suprascapula (fig. 22, 2).
The precoracoid (fig. 22, 5) forms a small forwardly-directed cartilaginous plate. The coracoid (fig. 22, 3) forms a much larger plate, the greater part of which is unossified and overlaps its fellow in the middle line, the two being overlapped by the sternum. Around the glenoid cavity is an area which is mainly ossified and is continuous with the scapula.
B. The Anterior limb.
This is divisible into three parts, the upper arm or brachium, the fore-arm or antibrachium, and the manus.
The upper arm includes a single bone, the humerus.
The humerus is a slender bone cylindrical in the middle and expanded at either end, the proximal part forms a rounded head which articulates with the glenoid cavity. Along the proximal part of the anterior or pre-axial surface runs a strong deltoid ridge. The proximal part of the postaxial surface also bears a small outgrowth.
The fore-arm contains two bones, the radius and ulna, both of which are small and imperfectly ossified at their terminations.
The radius (fig. 23, B, 11) or pre-axial bone is rather the larger of the two, and is considerably expanded at its proximal end. The ulna or postaxial bone is somewhat expanded distally, but is not drawn out proximally into an olecranon process.
The manus consists of two parts, a group of small bones forming the carpus or wrist, and the hand.