100 



THE BONES. 



Fig. 63. 



attachment. The internal condyle presents, posteriorly and inwardly, near 

 the posterior extremity of the intercondyloid notch, a roughened depression 

 tor the insertion of the fibre-cartilaginous meniscus interposed between the 

 external condyle and the corresponding articular plane of the tibia, It is 

 surmounted outwardly, i.e., on the side opposite to the intercondyloid 

 notch, by a large tubercle of insertion. The trochlea, a wide pulley on 

 which the patella glides, is situated in front of the condyles. It is slightly 

 oblique downwards and inwards, and appears to continue in front the inter- 

 condyloid notch. Of the two lips which border its cavity laterally, the 

 internal is the thickest and the most prominent. 

 Between the external and the corresponding con- 

 dyle is seen a digital fossa for muscular insertion. 

 Structure and development. The femur, very 

 spongy at its extremities, is developed from four 

 principal centres of ossification : one for the body, 

 another for the articular head, the third for the 

 trochanter, and the last for the inferior extremity 

 alone. 



LEG. 



This has for its base three bones : the tibia, 

 peroneus (or fibula), and the rotula (or patella),, 



1. Tibia. 



The tibia is a long, prismatic bone, thicker at 

 the superior than the opposite extremity, and 

 situated between the femur and the astragalus, 

 in an oblique direction downwards and backwards, 

 constituting the principal portion of the leg. 



Body. This offers for study three faces and 

 three borders. The faces are wider above than 

 below. The external is almost smooth, and is 

 concave in its superior part and convex below, 

 where it deviates to become the anterior. The 

 internal, slightly convex on both sides, presents, superiorly, deep imprints 

 lor the attachment of the adductor muscles of the thigh and the semi- 

 tendinosus. The posterior, nearly plane, is divided into two triangular 

 surfaces : one, superior, slightly roughened, serves for the attachment of the 

 popliteus muscle ; the other, inferior, much more extensive, is furrowed into 

 numerous longitudinal crests which give attachment to the perforans 

 muscle. On the limit of these two surfaces is remarked the nutrient foramen 

 of the bone. The borders are distinguished as anterior, external, and internal. 

 The first is rounded, and not very salient in its inferior two-thirds ; it forms 

 in its superior third, a curved crest, with the concavity external, which joins 

 the anterior and superior tuberosity of the bone ; this has received the name 

 of the tibial crest. The external border is very thick and concave above, 

 where it constitutes, in common with the fibula, the tibial arch. The 

 Internal is also very thick, straight, and provided superiorly with some 

 Calient tubercles to which the popliteus is attached. 



/^riwiJtert^-The superior extremity, the most voluminous, is formed by 



.three iubertoitiqp/.'feji Anterior and two lateral, which are external and 



r mterjiaU ^he f first ,he smallest^ is a rugged process continuous with 



ihC" ib"ufl 'crest f aa4 r separated from the external tuberosity by a wide and 



SECTION OF LEFT FEMUR, 

 SHOWING ITS STRUCTURE. 



