TSE HUMERUS. 227 



der ends as a thin tendon ranging from 1-3 cm. long. The details 

 of its indirect connection, through the latissimus, with the bicipital 

 arch (Fig. 73), and thus with the humerus, may be examined more 

 conveniently after the dissection of the pectorales. 



Remark.— This muscle does not exist in man, where the group 

 of dermal muscles is represented only by the M. plaiysma mycddes 

 upon the sides of the neck, and by certain muscles of the face. 



§ 631. Explanation of Figures 68-71 inclusive.— These represent respectively the 

 cephalic (outer), ventral (anterior), caudal (inner), and dorsal (posterior) aspects of the left 

 humerus. 



A shaded representation of the ventral aspect of the right humerus is given in Fig. 46. 

 These four figures are little more than outlines for the sake of indicating the attachment 

 areas and lines of the muscles or muscular divisions described in this work which arise 

 from or are inserted upon this bone. 



As in the figures of the scapula (Fig. 43, 44), the lines enclosing origins are composed 

 of dots, and those enclosing insertions of short dashes. 



In order to place the figures across the page, and so facilitate reference and comparison, 

 many of the parts are undesirably small, and several are so crowded as to be indistinct. 



The attachments are at least approximately correct for the majority of cases, but con- 

 siderable variation is to be expected. 



The identification of the muscles, especially those of the pectoralis group, is much 

 facilitated by the use of a carved wooden model of the humerus, enlarged 4 or 5 diameters 

 so as to increase both the attachment areas and the spaces between them. Such a model, 

 made by Mr. H. W. Turner, a special student, has been in use for several years in the 

 Anatomical Laboratory of Cornell University. 



The following features of the humerus itself are shown and sufficiently described in 

 the descriptions of Fig. 45 B and Fig. 46 : — 



Cn.{canaUs) bicipitalis (69, 70), §§ 403,409; capitsUum (69), § 410 ; caput articulare 

 (71), §§ 403, 411 ; crista deltoidea (68, 69), § 413 ; crs. (crista) epicondylaris (68, 71), § 415 ; 

 epieondylns (69, 71), S 415 ; epitroclilea (69, 70, 71), § 416 ; Fm. (foramen) epitroehleare 

 (69, 70, 71), § 417 ; trocUn (69, 71), §§ 405, 420 ; trocUter (68, 69, 71), §§ 406, 430 ; trochlea 

 (69), § 430. 



The following parts are not designated upon these figures, but may be recognized from 

 the other figures and descriptions : — 



Crista 'pectoralis (Fig. 46, § 413) ; fossa ulnaris and fossa radiaUs (Fig. 46, § 418) : fossa 

 trochiteriana (Fig. 45 B, §§ 404, 679). 



The following parts are not described elsewhere : — 



Crista epitrochlearis. — This name may be applied to the ridge which extends proximad 

 from the epitroclilea (Fig. 69). 



Fm. (foramen) meduUare — The medullary or nutrient foramen (Fig. 70). — This opens 

 upon the caudal aspect of the diaphysis, at about the junction of the middle and distal 

 thirds of the bone. It points distad from the surface. 



Fs. (fossa) olecranalis — The olecranon fossa (Fig. 71). — This is a deep and irregular 

 depression upon the dorsal aspect of the extremitas distalis. When the antebrachium is 

 extended, the olecranon of the ulna is received by it. We have never observed a perfora- 

 tion of the bone at this point, as is sometimes the case with man. 



