TEE POSTERIOR LIMBS, 137 



Thigh. 

 This has for its base one bone — the femur. 



Femur (Figs. 89, 90). 



The femur (os femon's) is a long, pair bone situated in an oblique direction 

 downwards and forwards, between the coxa and the principal bone of the leg ; 

 it is divided into a bod/j (or shaft) and t/ro extremities. 



Body. — It is irregularly cylindrical, and presents for study four faces. The 

 e^.rtnrial, internal, and anterior., confounded with one another, are regularly 

 rounded and almost sniooth, showing only some slight imprints and vascular 

 grooves. The posterior, nearly plane, and wider above than below, oifers : 1. 

 Outwardly and towards the superior third, an uneven circular surface. 2. On 

 the same level, and inwardly, a slight crest, oblique downward.** and outwards. 

 ?K In the middle, a very extensive roughened surface, having the form of an 

 obliquely angular parallelogram, for the attachment of the great adductor muscle 

 of the thigh. 4. Below this surface, a large vascular groove running obliquely 

 outwards and downwards. 



On the limit of the posterior and external faces are found, towards the upper 

 third, a large rugged, flattened eminence, curved in front, and termed the 

 suhtrochanterian crest (or external smidl trochanter ^), because of its position under 

 the trochanter ; below, a deep fossa, named the subcondyloid, garnished at its 

 bottom with asperities, and bordered in front by an uneven lip. On the limit 

 of the posterior and internal face, there are ol)served from above to below : 

 1. The smcdl trochanter — a large scabrous tuberosity, elongated in conformity 

 with the bone, and situated near its upper fourth. 2. A marked longitudinal 

 imprint for the attachment of the pectineus ; behind, it is confounded with the 

 surface for the insertion of the great adductor muscle of the thigh, and presents, 

 in front, the nutrient foramen of the bone. :^). The origin of the great posterior 

 fissure. 4. Quite below, a collection of large tubercles which form the supra- 

 condyloid crest. 



Extremities. — The superior extremity is sensibly flattened before and behind, 

 and shows : 1. Inwardly, an articular head which is received into the cavity of 

 the acetabulum. This head is separated from the other portion of the body by 

 a neck, which is, however, not well marked in the Horse, and forms two-thirds 

 of a sphere, excavated in its internal part by a very deep cavity for ligamentous 

 insertion. 2. Outwardly, a very large eminence — the trochanter major, or great 

 {external) trochanter, in which is recognized, as in the trochlea of the humerus : 

 a summit, much more elevated than the articular head, and slightly bent inwards ; 

 a convexity, encrusted with cartilage, and anterior to the summit, from which 

 it is separated by a narrow and deep notch ; a crest situated under the convexity, 

 and formed by a tuberculated surface, on which one of the tendons of the middle 

 gluteus muscle becomes inserted, after gliding over the convexity. 8. Posteriorly, 

 the trochanteric ox digital fossa — a deep cavity studded with imprints, and circum- 

 scribed, outwardly, by a salient lip {trochanteric ridge), which descends vertically 



' Thi8 is tlie third trochanter of Cuvier, and takes the place of the external and superior 

 branch of the linea a^pera of Man. (It is the external small trochanter of Percivall, and the 

 middle trochanter of Leyh ) 



