FEMUR. 



89 



FEMUR. 



(Fig. 21.) 



The OS femoris, femur, or thigh bone, the largest, thickest, 

 and strongest bone in the body, belongs to 

 the class of long or cylindrical bones, and 

 is placed in a direction obliquely down- 

 wards and forwards, articulating with the 

 cotyloid cavity of the os innominatum, and 

 also with the tibia and patella. 



The shaft is irregularly cylindrical, and 

 has two surfaces and tw^o borders. The 

 anterior surface is smooth, jDroininent, and 

 marked by a few muscular imjirints. The 

 posterior surface is flattened and expanded 

 at its upper part, and presents, towards the 

 external part of its upper third, a circular 

 roughened surface for the insertion of part 

 of the triceps adductor muscle ; internal to 

 which a slight ridge runs obliquely upwards 

 and inwards to join the internal trochanter, 

 to this the ischio-femoralis muscle is in- 

 serted. About its middle third is a rough- 

 ened surface, for the attachment of the 

 adductor brevis and part of the adductor 

 longus muscles. The external border, which 

 separates the anterior from the posterior 

 surface, presents a prominent ridge, on the 

 upper third of which is a sharp, flat pro- 

 tuberance, the troclianter 'ininor, curved 

 forwards, and affording attachment to the 

 gluteus externus and vastus externus 

 muscles. At the lower third of this border 

 is a deep, oval, roughened pit, the supra- 

 condylold fossa, from which the flexor 

 perforatus muscle arises ; and about level 

 with this, towards the inner side, is an aggregation of tubercles 

 forming the supra-condyloid crest, where arises one portion of 

 the gastrocnemius muscle. The internal border, dividing the 

 anterior from the posterior surface internally, presents near its 



Fic. 21. 



Posterior view of left femur 

 of a Horse. 1, Head ; 2, Tro- 

 cliaiiter major ; 3, Trochanter 

 minor ; 4, Trochanter interims; 

 5, Notch for the rouiid liga- 

 ment ; 6, Trochanteric fossa ; 

 7, 8, Places of attachment for 

 the lateral ligaments ; 11, The 

 condyles, separated by the 

 intercondyloid groove ; 10, 

 Supra-condyloid fossa. 



