The bones of the fore limb are humerus, ulna, radius, carpus, metacarpus, and phalanges. =The Humerus.= _Location._—The humerus constitutes the arm, which, when at rest, lies parallel to the dorsal vertebræ. It articulates superiorly with the glenoid cavity, a shallow ball-and-socket joint, formed by the scapula and the coracoid; and inferiorly with the ulna and radius. _Description._—The proximal extremity of the humerus is provided with a trochanter (Fig. 11, _G_, No. 5) and a large oval head or caput humeri, which articulates in the glenoid cavity. The head is an elongate, semi-oval convexity, with the long axis transverse from the radial to the ulnar side and with the ends continued into upper and lower crests. The upper crest of the head of the humerus is on the radial side and the lower crest on the under side. Under this latter crest there is a _pneumatic fossa_ (Fig. 11, _F_, No. 1), at the upper end of which there is an opening into the bone, the _pneumatic foramen_, which brings the air-sac into communication with the air space of the bone. The shaft, or corpus humeris, is irregularly cylindrical and slightly S-shaped. The proximal part of the shaft, which is expanded on the palmar side, is concave across and convex lengthwise. The distal part is slightly flattened. The shaft of the humerus is almost cylindrical. The distal extremity of the humerus is provided with two articular condyles, one of which articulates with the ulna and the other with the radius. On the radial side of the palmar surface there is a ridge; and on the ulnar side of the same surface there is a second ridge diverging to the opposite tuberosity. The radial surface is a narrow, subelongate convexity, extending from the middle, approximately, of the palmar surface, obliquely to the lower part of the radial tuberosity. The two _articular convexities_, or _trochlea_, at the distal end of the humerus are bent toward the palmar aspect, the _anconal aspect_ is the side on which the elbow is situated. The inner convexity is the larger and articulates with the ulna. To the outside is the _processus cubitalis humeri_. The outer articulates with the radius and is so arranged that the radius makes a greater flexion than the ulna. At the lower end of the humerus there is a depression which receives the anconeus of the ulna during flexion and extension of the forearm. On the shoulder- and elbow-joint are found grooves over which the tendons glide, at which places sheaths are provided. This arrangement also aids in keeping the capsular ligament in place. =The Ulna.= _Location._—The ulna, larger than the radius, is bent and articulates with the radius only at the ends. The two bones are bound together by a ligamentous band. It also articulates superiorly with the distal end of the humerus, and inferiorly with the carpus. When the wing is folded the radius is superior and a trifle to the inner side of the ulna.