780 MR. ST. GEORGE MIVART ON THE [JunC 27, 



The sterno chido-mastoid is of large size (figs. 1, 2, 2 a, 6 & 8, 

 S. G. 31.). It arises by muscular fibres from rather more than the 

 lower half of the outer margin of the anterior surface of the clavicle, 

 and by a very strong tendinous fascia (fig. 8, t.) from the anterior 

 part of the true sternum. This strong fascia extends forwards (co- 

 vered by the pectoralis major) ; and the muscular fibres springing 

 from it arise in a point between the pectoralis major and the lower 

 portion of the deltoid. The muscle passes forwards, overlapping 

 first the omo-hyoid, and afterwards the levator clavicula). It then 

 becomes intimately united with the outer side of the anterior part of 

 the trapezius, and is inserted into the outer half of the postero- 

 superior margin of the parietal process and into the postero-external 

 end of the parotic process. 



Slerno-Jujoid. This was so much injured in my specimen that I 

 am unable to describe it ; according to Cuvier* and Meckelf, how- 

 ever, it proceeds from the outer part of the sternum to the os hyoides. 



The omo-hyoid (figs. 2 & 7, O. H.) is rather large, and arises from 

 rather more than the upper half of the clavicle, where externally it 

 is adjacent to the trapezius and sterno-cleido-mastoid and internal 

 to the deep layer of the first part of the deltoid. It is mainly in- 

 serted into the posterior cornu of the hyoid ; but some fibres pass 

 (nearer the middle line of the body) to the body of the os hyoides. 



Levator duviculcB. This large muscle has a strong tendinous 

 origin from the transverse process of the atlas. Passing backwards it 

 emerges from beneath the sterno-cleido-mastoid (figs. 2 & 7, L. C), 

 and, spreading out, is inserted into the summit (or acromial end) of 

 the clavicle and into the anterior margin of the scapula. About the 

 lower half of its insertion is conterminous, posteriorly, with the origin 

 of the upper (or second) portion of the deltoid ; internally this 

 muscle is in close juxtaposition with the second part of the subsca- 

 pularis and the fourth part of the serratus magnus (fig. 7, L. C). 



The trieej)s (figs. 1, 2, 0, 8, 9 & 10) arises by four distinct heads J:, 

 of which two are long, descending from the scapular arch : — 



(1) The first part or external long head (which appears to answer 

 to the ordinary long head of this muscle in mammals) arises from 

 the strong, tendinous strap, or ligament before described as passing 

 from the axillary margin of the scapula to the head of the humerus 

 and as binding down the infraspinatus. Thus the head may be said 

 to arise by a bifurcating tendon like that of the rectus femoris of 

 Man (figs. 1, 2 & 9, T. 1). 



(2) The second part, or internal long head (fig. 9, T. 2), takes 

 origin by a long and rather slender tendon, which also bifurcates 

 above, — its lower bifurcation being attached to the postero-internal 

 angle of the deep surface of the coracoid, while its upper bifurcation 

 fuses with that before- described tendinous arch into which the costo- 

 coracoid muscle is inserted. 



This second head of the triceps soon joins with the first head, and 

 at its union with the latter receives a small tendinous slip (fig. 9, t.) 



* Loc. cit. vol. iv. part ], p. 531. t Loc. cif. vol. viii. p. l."^5. 



\ Meckel, loc. cit p. .3G4. 



