THE ANTERIOR SCAPULAR REGION 201 



3. M. Tares Minor. Origin, from narrow grooved surface 

 or dorsum of the scapula close to the axillary border, from 

 septa between it, the teres major, and inf raspinatus ; inserted 

 into the lowest facet on the great tuberosity and into the 

 shaft for a short distance below. 



May be a bursa under its insertion. It is behind the long 

 head of the triceps and capsule; the dorsal scapular artery 

 passes between it and bone. 



4. M. Teres Major. Is a thick somewhat flattened muscle. 

 Origin, from the oval surface on the back part of the inferior 

 angle of the scapula, and the fibrous septa common to it, and 

 the teres minor and inf raspinatus ; inserted, by a flat tendon 

 into the inner ridge of the bicipital groove of the humerus. 



The Anterior Scapular Region 



M. Subscapularis. Origin, by muscular and tendinous 

 fibers from the venter of the scapula and groove along the 

 axillary border; insertion, small tuberosity of the humerus 

 and into the shaft for a short distance. As in the deltoid, this 

 muscle contains two sets of septa one from the origin, and 

 one from the insertion for attachment of the oblique muscular 

 fibers. Some fibers from the axillary border of the muscle 

 are usually inserted into the capsule, known as the subscapularis 

 minor. 



There is a bursa between the muscle and the capsule, and 

 often another on its anterior surface (bursa coracobrachialis). 



Nerves. Supraspinatus and infraspinatus by the supra- 

 scapular nerve from the fifth and sixth cervical; others from 

 the posterior cord of the brachial plexus, deltoid, and teres 

 minor from the fifth and sixth cervical through the circum- 

 flex nerve; subscapularis by the fifth and sixth cervical through 

 the upper and lower subscapular nerves. 



Actions. Deltoid abducts arm to 90 degrees, posterior 

 fibers said to abduct only to 45 degrees; insertion of the trape- 

 zius corresponds to origin of the deltoid, so that the two are 

 continuous in action; anterior part of the deltoid draws the 

 humerus forward and rotates in; of both deltoids crosses the 

 arms over the chest; posterior part draws the humerus back- 

 ward and rotates out; supraspinatus, infraspinatus, and sub- 

 scapularis steady the capsule while the deltoid acts. The 



