192 MYOLOGY. 



SERRATUS MAGNUS. 



(Costo-subsca2mlaris. ) 



(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 subscaj)ularis 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 iuter- 

 costals ; externally with the subscapular and triceps extensor 

 muscles. 



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

 it elevates the neck, and is^so a subservient muscle of inspira- 

 tion; 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. — Anteriorly, from the supraspinous ligament, and 

 dorsal spines from the second to the thirteenth inclusive ; poste- 

 riorly 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. 



