Clavicle,                     or   collar-bone       | form shoulder

Scapula,                      „    shoulder-blade | girdle.

Humerus,                    „    bones of upper arm.

Ulna and Radius,        „     bones of forearm.

Carpal,                       „    bones of wrist.

Metacarpal,                „    bones of palm.

Phalanges,                  „    bones of fingers.

The clavicle is commonly known as the collar-bone.     It articulates by one end with the sternum (breast-bone) and  by the other end with the acromion process of the scapula.     It tends to keep the shoulders back.

Fig. 30.—Clavicle (Right).

The scapula is a flat triangular bone traversed at the back by a ridge, the spine of the scapula, which ends in the acromion process. There is another process called the coracoid, which arises from the top of the glenoid cavity. These two processes overhang the joint, and help to keep the humerus in place. The scapula has a shallow socket, the glenoid cavity, which receives the head of the humerus, and forms the shoulder-joint. In life this cavity is deepened by a rim of fibro-cartilage, the glenoid ligament ; the shallowness of the cavity renders the humerus liable to dislocation, but permits great freedom of movement, which is further secured by laxity of the ligaments which bind the bones together. The narrow part of the scapula behind the cavity is the neck.

Fig. 31.—Scapula (Right).

1, Spine; 2, acromion process; 3, coracoid process ; 4, superior border ; 5, superior angle; 6, posterior or vertebral border; 7, inferior or axillary border ; 8, inferior angle.

The under or anterior surface of the scapula is smooth, and glides over the back of the chest.