TERES MUSCLES. 35 



dor-si. Tlie lower border is in contact with the teres minor, with 

 which it is often united. The muscle lies on the scapula and the 

 scapulo-humeral articulation ; and there is sometimes a small bursa 

 between it and the capsule of the joint. 



Action. With the humerus hanging it acts as a rotator outwards ; and use. 

 and when the bone is raised it will move the arm backwards in 

 concert with the hinder part of the deltoid. 



The TERES MINOR (fig. 13, c) is a narrow fleshy slip, which is Teres 

 often united inseparably with the preceding muscle. It arises on minor; 

 the dorsiim of the scapula from a special impression along the upper origin, 

 two-thirds of the axillary border of the bone, and from an inter- 

 muscular septum on each side ; and it is inserted by a tendon insertion, 

 into the lowest of the three marks on the great tuberosity of the 

 humerus, as well as by fleshy fibres into the bone below that spot, 

 about an inch altogether. 



This muscle is partly covered by the deltoid ; it rests on the parts 

 long head of the triceps and the shoulder-joint. Underneath it around li ' 

 the dorsal branch of the subscapular artery turns on to the back of 

 the scapula. 



Art inn. The limb hanging, the muscle rotates it out and moves and use. 

 it back ; the arm being raised, the teres depresses the humerus. 



The TERES MAJOR MUSCLE (fig. 13, D) passes from the inferior Teres major: 



angle of the scapula to the humerus. Its origin is from an oval origin ; 



surface behind the inferior angle of the scapula, from the lower 



half of the axillary border of the bone, and from the interrnuscular 



septum between it and the teres minor. The fibres end in a tendon 



which is inserted into the inner edge of the bicipital groove of the insertion; 



humerus. 



The muscle assists in forming the posterior fold of the axilla, and 



uate beneath the axillary vessels and nerves near the humerus relations ; 

 (fig. 4). The upper border is contiguous to the subscapularis 

 muscle, and the lower is received into a hollow formed by the 

 latissimiis dorsi, which covers the teres behind at its origin, and 

 in front at its insertion. At the humerus the tendon of the 

 muscle is about two inches wide, and is placed behind that of the 

 latissimus : the two are separated above by a bursa ; but they are 

 united below, and an expansion is sent from them to the fascia of 

 the arm. A second bursa is frequently present between the teres 

 and the bone. 



Action. If the limb hangs, it is carried back behind the trunk, use on 

 and is rotated inwards by the muscle. The humerus being raised, swin s in s 

 the muscle depresses and adducts it. 



With the linib fixed by the hand the teres will cause the lower and fixed 

 angle of the scapula to move forwards. 



Below the scapula, where the teres muscles separate from one Triangular 

 another, is a triangular interval, which is bounded in front by the space> 

 shaft of the humerus, and above and below by the teres minor and 

 major (fig. 13). The space is divided into two by the long head 

 of the triceps. Through the anterior part, which is of a quadri- Quadriia- 

 lateral shape, the posterior circumflex vessels (a) and the circumflex teral s P ace - 



D 2 



