ANATOMY IN A NUTSHELL. 55 



angle and the triangular smooth surface at the root of the spine. (Plate XX.) 



Action. — To raise the superior angle of the scapula. 



XeryeSupply. — Third and fourth cervical, and frequently by a branch from 

 the nerve to the Rhomboidei. 



Blood Supply. — Vertebral, ascending cervical, superficial cervical, and 

 posterior scapular. 



Rhomboideus minor. — (Plate XVIII.) — Origin. — Ligamentum nucha 1 and 

 spinous processes of the seventh cervical and first dorsal vertebrae. 



Insertion. — Smooth surface at root of spine of scapula. (Plate XX.) 



Action. — To draw the scapula backward and upward. 



Nerve Supply. — Fifth cervical. 



Blood Supply. — Posterior scapular. 



Rhomboideus major. — (Plate XVIII.) — Description. — This muscle is 

 situated immediately below the minor, the adjacent margins of the two being 

 occasionally united. 



Origin. — Spinous processes of the four or five upper dorsal vertebrae 

 and the supra-spinous ligament. 



Insertion. — Into a narrow tendinous arch attached above to the lower 

 part of the triangular surface at the root of the spine, and below to the inferior 

 angle, the arch being connected to the border of the scapula by a thin mem- 

 brane. When the arch extends but a short distance, as it occasionally does, 

 the muscular fibers are inserted into the scapula itself. (Plate XX.) 



Action. — To draw scapula backward and upward. 



Nerve Supply. — The fifth cervical. 



Blood Supply. — Posterior scapular. 



Supraspinatus. — Description. — (Plates XXYIII-XY111.) — The supra- 

 spinatus muscle occupies the whole of the supraspinous fossa. The fibers 

 converge to a tendon which pas>e> across the upper part of the capsular liga- 

 ment of the shoulder joint.. to which it is intimately adherent. 



Origin. — (1) Internal two-thirds of supraspinous fossa. (2) Strong 

 fascia covering surface of fossa. (Plate XX.) 



Insertion. — Upper facet of greater tuberosity of humerus. (Plate XXIII.) 



A< tion. — Raises arm and supports tuberosity of humerus. 



Xf.rve Supply. — Fifth and sixth cervical through the suprascapular nerve. 



Blood Supply. — Suprascapular artery. 



Infraspinatus. — Description. — (Plates XXVII1-XVIII.) This is a thick, 

 triangular muscle which occupies the chief part of the infraspinous fossa. The 

 fibers converge to a tendon which glides over the external border of the spine 

 of the scapula and passes over the posterior part of t he capsular ligamenl of the 

 shoulder-joint. This tendon is occasionally separated from the -pine of the 

 scapula by a synovial bursa which communicates with the synovial cavity of 

 the shoulder-joint. 



Origin. — (1) Internal two-thirds of infraspinous fossa; (2) tendinous 

 fibers from ridges on its surface; (3) strong fascia covering it externally ami 

 separating it from the Teres major and minor. (Plate \ \ 



Insertion.— Middle facet of greater tuberosity of humerus. (Plate XXII.) 



