68 



ELEMENTS OF MAMMALIAN ANATOMY. 



enlarged extremities and a shaft whose cross-section is tri- 

 angular. It articulates with the femur and fibula proximally 

 and the fibula and astragalus distally 

 (Fig. 21 ). This is the longest bone in 

 the cat's skeleton. Between the concave 

 condyles on the proximal end is a notch 

 giving attachment to the crucial ligament 

 of the knee-joint (Figs. 41, 46). 



The prominences of the lateral and 

 medial aspects of the proximal extremity 

 are the external and internal tuberosities 

 respectively. Beneath the former is the 

 facet for articulation with the fibula (Fig. 

 41). The tubercle, a prominence on the 

 cranial side of this extremity, is for the 

 insertion of the ligamentum patellae, which 

 is really the termination of the tendon of 

 the quadriceps extensor muscle (Fig. 52). 

 On the caudal aspect between the con- 

 dyles is the popliteal notch. The sharp 

 cranial border of the bone forms the 

 crest. On the distal extremity is a proc- 

 ess, the internal malleolus, bearing two 

 grooves, the more caudal of which shel- 

 ters the tendon of the flexor longus digi- 

 torum muscle while the other is for the 

 tibialis posticus (Fig. 52). A facet is 

 present on the lateral aspect of this ex- 

 tremity for articulation with the fibula. 



The fibula in proportion to its length 

 is the slenderest bone in the skeleton. 

 It is the outer or lateral bone of the crus, and articu- 

 lates proximally with the tibia and distally with the tibia 

 and astragalus (Fig. 21). The proximal extremity is 



FIG. 42. INNER OR 

 MEDIAL ASPECT 

 OF RIGHT FIB- 

 ULA. 



a, Facet for tibia ; 

 ar, facet for as- 

 tragalus ; ex, ex- 

 ternal malleolus ; 

 h, head; s, shaft ; 

 t, articular sur- 

 face for tibia ; 

 gr, groove for 

 peroneus longus 

 muscle. 



