200 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM 



MUSCLES AND FASCLffi OF THE UPPER 

 EXTREMITY 



MUSCLES AND FASCLffi OF THE SHOULDER AND ARM 



The Acromial Region 



The deep fascia is strong and tendinous over the back of 

 the deltoid and inf raspinatus ; the infraspinatus fascia covers 

 the teres minor and splits at the posterior border of the deltoid, 

 a deep layer passing to the shoulder-joint under that muscle, a 

 superficial layer to the spine of the scapula over the muscle. 



M. Deltoidem. Origin, in three portions; an anterior from 

 the front of the outer third of the clavicle, a middle from the 

 point and outer edge of the acromion, a posterior from the 

 lower border of the scapular spine and triangular surface 

 at its inner end, and from the infraspinatus fascia. These 

 converge into the tendon of insertion into the deltoid tubercle 

 of the humerus. The anterior and posterior parts run by 

 long fasciculi into the marginal parts of the tendon; in the 

 acromial portion most fibers rise in a bipenniform manner 

 from the sides of four tendinous septa; the oblique fibers are 

 inserted below into three septa which come up from the humerus 

 to alternate with those above. Some fibers pass from the tip 

 of the acromion to the tips of the lower septa, and some from 

 the tips of the upper septa directly to the humerus. 



The Posterior Scapular Region 



1. M. supraspinatus, from inner part of the supraspinous 

 fossa to region of the notch, from supraspinous fascia and 

 transverse ligament; adherent to capsule and infraspinatus 

 tendon; inserted into the upper of the three facets on the great 

 tuberosity of the humerus. 



2. M. infraspinatus, rises from the inner two-thirds of the 

 infraspinous fossa, from the infraspinatus fascia, -and under 

 surface of the spine; fibers converge to a tendon concealed 

 within the muscle and inserted into the middle facet of the 

 great tuberosity. It may be inseparably connected with the 

 teres minor. 



