192 MYOLOGY. 



SERRATUS MAGNUS. 



(Costo-subscaj)ularis. ) 



(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 inter- 

 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 also 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. 



SUPERFICTALIS 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 

 vertebra. 



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. 



