FEMUR. 



89 



FEMUR. 



(Fig. 21.) 



The OS feinoris, 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 innominatura, and 

 also with the tibia and patella. 



The shaft is irregularly cylindrical, and 

 has two surfaces and two borders. The 

 anterior surface is smooth, prominent, and 

 marked by a few muscular imprints. 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 abductor muscle; internal 

 to which a slight ridge runs obliquely up- 

 wards and inwards to join the internal 

 trochanter, to this the ischio-femoralis muscle 

 is inserted. About its middle third is a 

 roughened 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 trochanter minor, 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- condyloid 

 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 gastro- 

 cnemius muscle. The internal border, dividing the anterior from 

 the posterior surface internally, presents near its upper third 



Fio. 21. 

 Posterior view of left femur 

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

 chanter major ; 3, Trochanter 

 minor ; 4, Trochanter in temus: 

 5, Notch for the round 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. 



