MR 



OX DASYriJS SEXCINCTUS. 531 



its fibres fuse with that most posterior factor of the triceps which joins the Utifaimv* 

 dorm as this latter gives off its dorso-epitrochlear contingent to the elbow, also with 

 that portion of the latissimus dorsi which passes np to the usual insertion at the shaft of 

 the humerus. 



It is inserted tendinously into the humerus, immediately below the latt r muscle. 



Latissimus dorsi.— This muscle arises from the " metapophyeei " (Owen) of the lumbal 

 vertebrae, and from the lumbar aponeurosis, between those posterior fibres of the dorsal 

 portion of the trapezius which terminate in this aponeurosis and the anterior libra of 

 origin of the gluteus maximus—aho from fascia which lies beneath the factor of the 



trapezius mentioned above, and which covers one of the longitudinal dorsal muscles. Its 

 upper fibres of origin are scarcely, if at all, to be differentiated from tho lowermost 

 portion of the rhomboidei muscles, or muscle. 



Certain fibres, moreover, take origin from the bony elements of all tho true ribs from 

 the fifth downward, those which arise from the fifth to the ninth inclusive passing 

 straight upwards towards the tendon of insertion of t lie muscle. 



The whole of the outer aspect of the thorax is, in short, completely covered by the 



- 



fibres of this muscle. 

 Those costal elements which derive their origin from the ribs posterior to the ninth, 



and that portion of the muscle which arises from the dorsal region of the trunk, pass 

 together obliquely upwards and onwards, and contribute mainly to the formation of the 

 well-developed dorso-epitrochlien. This cubital offset from the latimmtm dorti, after 

 dropping a few fibres in the fascia covering the elbow, is continued over this process, and 

 proceeds for some distance along the inner aspect of the forearm, to be finally lost in the 



fascia of this region. 

 Those costal fibres mentioned above as taking origin from the ribs between the fifth 



and ninth inclusive, after fusing with the proximal portion of the dorso-epi trochlear 

 branch, and also very slightly with the teres major, at its origin, pass gradually into the 

 terminal tendon of the latissimus tfom-whieh, after passing under the axillary vessels 

 and nerves, is inserted into the shaft of the humerus, on its inner aspect, a little below, 

 and to the outer side of, the insertion of the - short " variety of the coracobrachial*, 



and above that of the teres major. m m 



Certain muscular fibres take origin from the ribs between the fifth and mnth mc usive, 

 anterior, but close, to those costal elements of the latmimus ^already described u 

 arising from the same ribs, and pass straight upward to that portion of the broad tor- 



minal tendon of ikepectoraU. major which has the highest motion mto the humerus. 



Cuvier's representations of this muscle are clear, and agree very fairly with my obser- 

 vations'. The costal slip, last described, is figured very dis inctly as passing outs de , he 



vernal oblique, upwards, and slightly outwards, over the axUla over ^'^^^ 

 and biceps, to be inserted into the humerus above, but in company with the upper pa, t 



aixu <^oc^, tu uc xnac M/t + nwt v,o maior of which muscle, moreover, if his 



of the tendon of insertion ^ of the i-^ 



appended symbols do not belie his meaning, tuvier a PP j 



fig. 2, and 



4 



VOL. XXVI. 



