192 MYOLOGY 



SERRATtJS MAGNUS. 



{Costo-suhacapularis. ) 



(PL. III. 10. 15.) 



Situated between the shoulder and chest, and on the side of 

 the neck, this is a large fan-shaped muscle ; it may be divided 

 into a cervical and a costal portion, and consists of several bundles 

 with many tendinous intersections, converging upwards to the 

 common point of insertion. 



Origin. — Anteriorly, from the transverse processes of the five 

 posterior cervical vertebrae ; postero-inferiorly, from the external 

 surfaces of the eight true ribs, from about their middles to their 

 cartilages. 



Insertion. — Superiorly to the venter surface of the scapula, 

 between the origin of the subscapularis and the insertion of the 

 rhomboidei. 



Relation. — Anteriorly with the splenius ; superiorly with the 

 rhomboidei ; supero-posteriorly with the longissimus dorsi ; poste- 

 riorly with the great oblique muscle of the abdomen, with which 

 it interdigitates ; inferiorly with the pectorals ; internally with the 

 ribs, longissimus dorsi, splenius, cervical vertebrae, and intercostals ; 

 externally with the subscapular and triceps extensor muscles. 



Action. — It depresses the scapula ; when the limbs are fixed, it 

 elevates the neck, and is also a subservient muscle of inspiration ; 

 but it chiefly serves with its fellow as a muscular sling, in which 

 the body is suspended between the anterior limbs. 



SUPERFICIALIS COSTARUM. 



{Dorso-costalis.) 



(Pl. II. 49.) 



Placed on the supero-lateral part of the back, this muscle is 

 broad, thin, and digitated, and consists of an anterior and a 

 posterior portion. 



Origin. — Ajiteriorly, from the supraspinous ligament, and dorsal 

 spines from the second to the thirteenth inclusive; posteriorly from 

 the spines of the last eight dorsal and anterior lumbar vertebrae. 



Insertion. — The anterior part to the nine ribs behind the 

 fourth, just below their angles, and to their anterior borders ; 

 the posterior part to the posterior borders of the last nine ribs. 



