ANATOMY IN A NUTSHELL. 



43 



muscle is enclosed. The insertion of this muscle is larger than the origin. 



Origin. — By strong tendon from the first rib and its cartilage at their 

 junction in front of the rhomboid ligament. 



Insertion. — Under surface of the clavicle in a deep groove about its middle 

 third. (Plate XL) 



Action. — Depresses shoulder by drawing the clavicle downward and for- 

 ward. 



Nerve Supply. — Filaments from the fifth and sixth cervical. 



Blood Supply. — First intercostal and short thoracic arteries. 



Deltoid.— Description.— (Plates XYIII-XIY-XY-XYI. i— The Deltoid is 

 a triangular muscle which gives the rounded outline to the shoulder. It i- 



PLATE XII. 



ANTERIOR STERNO-CLAUCULAR LIGAMENT 





THE INTERARTICULAR FIBRO-CARTILAGE 



THE JOINT BETWEEN THE STERNUM 

 A\D SECOND COSTAL CARTILAGE 





Sterno-Claviculak Articulation. 



large and thick. It surrounds the shoulder-joint in the greater part of its 

 of its extent, covering it on it- outer >ide and in front and behind. It- •: 

 surface is separated from the head of the humerus by a large sacculated syn- 

 ovial bursa. It- anterior border i- separated at its upper part from the Pec- 

 toralLs major by a cellular interspace which lodges the cephalic vein and the 

 humeral branch of the acromial thoracic artery. This muscle i- remarkably 

 coarse in its texture. 



Origin.— (Plate.- XI-XX.> — (1) Outer thiol of anterior border and upper 

 surface of clavicle. (2) Outer margin and upper surface of acromion proc< 

 (3) Lower lip of posterior border of -pine of scapula as far back as the trian- 

 gular surface at the inner end. The part arising from the acromion process 



