Breast bone and Wing of an eagle
2038). The anterior extremity of a bird, although an instrument of flight, is found, when stripped of those feathers and long quills that form the extensive surface presented by this member during life, still closely to adhere to the general type in accordance with which this part of the skeleton is invariably constructed. The framework of the shoulder exhibits the scapula (fig. 355,b), the clavicle (d), and the cora-coid element (c), notwithstanding that these bones, forming, as they do, the basis of a limb so vigorous, and wielded by such powerful muscles, are necessarily modified in their form and general arrangement, so as to constitute strong buttresses adapted to keep the shoulder-joint firm and steady during flight. The scapula (b) is a long and slender bone placed upon the ribs, and lying parallel to the spine along the dorsal region of the thorax, imbedded in the muscles to which it gives attachment, while at its fixed extremity it assists in forming the cavity of the shoulder-joint. The coracoid bone (c) is the great support of the shoulder; for while at one extremity it sustains the wing, at the opposite it is firmly and securely united to the sternum by a broad articulation. But the most peculiar element of this apparatus is the furculum, or forked bone (d), composed of the conjoined clavicles, which, being anchylosed together in the mesial line, and also strongly connected with the shoulder-joint, materially add to the stability of the whole.
(2039). In the wing itself, the humerus (f) is at once recognized, as also the ulna (g) and the radius (h.) But in some birds, as in the Penguin, the student might be at a loss to identify one or two small bones (p), forming a kind of patella to the elbow-joint; these appear to be the representatives of the olecranon process detached from the ulna. The carpus (i) consists of only two small bones. The metacarpus is formed of two pieces (k, I), anchylosed together at their two extremities; and these, with two, or in some cases three rudimental fingers, complete the wing. The largest finger consists of two, or sometimes three phalanges (m, o); a second (n) offers but a single joint; and the third, which is a mere rudiment when present, is an appendage to the radial side of the carpus.
Bald Eagle Pictures:-