160 AXATOJflCAL TECHNOLOGY. 



narrow longitudinal depression roughened for the attachment of the conjoined tendons of 

 the MM. tens (nipjor) and latissimus (dorsi). It is indicated by an interrupted line on 

 Fig. 70. On Fig. 40 it does not appear, but its proximal end would be opposite the proxi- 

 mal end of the longer brace. Its length equals the dorso-ventral diameter of the bone 

 opposite its distal end. 



§ 415. Epicondylus — The epicondyle or external condyle (Fig, 30, 46, 68, 69, 71, 74). — 

 This is a rough subconical eminence upon the cephalic aspect of the distal extremity. To 

 it is attached the proximal end of the cephalic (external) lateral ligament of the elbow, 

 and from it arise the MM. Extensor ulnaris and Ext. minimi. Obliquely proximad from 

 the epicondylus extends the Crista epicondylaris, which loses itself on the dorsal aspect of 

 the diaphysis nearly opposite the point of nearest approximation of the deltoid and pectoral 

 crests upon the ventral aspect. 



The epicondyle has been called "outer" or "external condyle," and more recently 

 by Markoe {!) and others " external epicondyle." 



§ 416. Epitrochlea — The epitrochlea or internal condyle (Fig. 30, 46, 69, 70, 71, 75). — 

 This is is a rough subconical eminence upon the caudal aspect of the distal extremity. It 

 is larger than the epicondylus, and springs abruptly from the nearly plane caudal surface 

 formed by the caudal prominence of the trochlea. Proximad, however, it is directly con- 

 tinuous with the bar forming the caudal boundary of the Fm. epitrochleare. 



§ 417. Fm. {Foramen) Epitrochleare — The epitrochlear or supracondyloid foramen 

 (Fig. 30, 46, 69, 70, 75, 105). — This is a narrow perforation from the ventral to the dorsal 

 aspect of the humerus near the caudal side of the distal extremity. Through it pass the 

 N. medius and the A. brachialis on their way from the dorso-caudal to the ventral aspect 

 of the arm. 



In the cat, the Fm. epitrochleare is within the natiirally assigned limits of the Ext. 

 distalis, but it is wholly within the diaphysis ; its distal boundary is sometimes very near 

 the diaphysio-epiphysial suture, and sometimes separated therefrom by a space equal to 

 the longer diameter of the orifice. 



The Fm. epitrochleare exists in the other Felidae and in some other Carnivora (Flower, 

 A, 246), and occasionally — partly circumscribed by ligament — in man (Humphrey, A, 373 ; 

 Quain, A, I, 87). Usually, however, the human humerus presents merely an emargination 

 of the bone, along which pass the median nerve and the brachial artery. 



§ 418. Fossa Radialis and Fs. UXnaris — The radial and ulnar fossae of the humerus 

 (Fig. 46). — On the ventral (anterior) aspect of the distal extremity of the humerus, just 

 proximad of the arthral surfaces of the trochlea and capitellum, are two slight depressions, 

 against which, in the strongly flexed condition of the elbow, abut the coronoid process of 

 the ulna (Fig. 30, Pre. coronoideus), and the side of the capitellum or proximal arthral end 

 of the radius (Fig. 30) ; hence their respective names. Between the two fossae, especially 

 in well marked bones, is a slight ridge. The Fossa iilnaris is described, but not named, 

 by Straus-Durckheim (A, I. , 513). 



§ 419. The Fossa olccranalis, on the dorsal aspect of the distal extremity, will be 

 described in connection with Fig. 71. 



§ 430. Trochin and Trochitcr — The caudal (lesser or inner) and the cephalic (greater 

 or outer) humeral tuberosities (Fig. 30, 45, 68-71).— These parts of the proximal extremity 

 have been described in connection with Fig. 45, and their muscular attachments will be 

 mentioned in connection with Fig. 68-71. See also above, CanaliH licipitalis. It has been 

 mentioned under Fi;^. 45 that while the trochin is wholly caudal in position, the trochiter 

 is about equally ventral and cephalic. 



Trochlea— {Y\g. 40, 69, 71).— This is the half saddle shaped arthral surface at the 

 caudal side of the distal end of the humerus. Its caudal border is raised and sharply 



