176 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM 



First Layer. 1. Trapezius (cucullaris), or hood muscle. Origin, 

 inner third superior curved line of occipital bone, ligamentum 

 nuchae, spinous processes of the seventh cervical, and of all 

 the dorsal vertebrae and supraspinous ligament; insertion, 

 fibers converge to shoulder girdle; superior ones to outer third 

 or half of posterior border of clavicle; middle fibers horizontally 

 to inner margin of acromion and superior lip of scapular spine; 

 inferior fibers up and out to a triangular tendon gliding over 

 the inner extremity of the spine of the scapula and inserted 

 into a tubercle on its upper lip. The aponeuroses of the two 

 muscles form an ellipse widest at the seventh cervical spine. 



2. M. Latissimus Dorsi, broad and flat at its origin, narrow 

 at its insertion. Origin, spinous processes of the lower six or 

 seven dorsal vertebrae, posterior layer of the lumbar aponeu- 

 rosis which attaches it to the lumbar and sacral spines and 

 iliac crest, from the external lip of the iliac crest in front of 

 the lumbar aponeurosis; from the last three or four ribs by 

 digitations interposed between those of the external oblique; 

 often by a slip from the inferior angle of the scapula. Its 

 upper fibers are nearly horizontal, middle oblique, and the 

 lower vertical; it winds around the teres major and in front 

 of it, and is inserted by a tendon 1| inches wide into the floor 

 of the bicipital groove, a little higher than the teres major, 

 and by its upper edge into the inner lip of the groove limiting 

 the insertion of the subscapularis. 



Second Layer. 1. M. Rhomboideus Minor. Origin, seventh 

 cervical and first dorsal spines and ligamentum nuchae of 

 that region; insertion, vertebral margin of scapula opposite 

 triangular surface at commencement of the spine. 



2. M. Rhomboideus Major. Origin, spinous processes of 

 four or five upper dorsal vertebrae and supraspinous ligament; 

 insertion, vertebral margin of scapula between the spine and 

 the inferior angle. The greater part of its fibers are not fixed 

 directly to bone, but end in a tendon attached to the lower 

 angle of the scapula, so that the muscle acts more especially 

 upon this angle. 



3. Levator Angulis Scapuli. Origin, by tendinous slips 

 from the transverse process of the atlas, the posterior tubercles 

 of the transverse processes of the second, third, and fourth 

 cervical vertebrae; insertion into the posterior border of the 



