248 



OSTEOLOGY. 



BICEPS 



FlBULAR 



COLLATERAL 



LIGAMENT OF KNEE 



distal to this the areas for the origins of the peronseus longus and extensor digitorum 

 longus are often crisply defined. The circumference of the medial condyle is grooved 

 postero-medially for the insertion of the tendon of the semi-membranosus. 



In front of the condyles, and about an inch distal to the level of the condylic sur- 

 faces, there is an oval elevation called the tuberosity of the tibia. The proximal 

 half of this is smooth and covered by a bursa, while the distal part is rough and 

 serves for the attachment of the ligamentum patellae. 



Considered in its entirety, the proximal extremity of the tibia is broader 

 transversely than antero-posteriorly, and is inclined backwards so as to overhang 

 the shaft posteriorly. 



The corpus tibiae (body) is irregularly three -sided, possessing a medial, a 

 lateral, and a posterior surface, separated by an anterior crest, a medial margin, and 

 a lateral or interosseous crest. It is narrowest about the junction of its middle 

 and distal thirds, and expands proximally and distally to support the extremities. 

 Running along the front of the bone there is a gently-curved, prominent margin, 

 the crista anterior, confluent proximally with the tuberosity, but fading away distally 



on the anterior surface of the 

 distal third of the bone, where 

 it may be traced in the direc- 

 tion of the anterior border of 

 the medial malleolus. This 

 is the anterior crest or 

 shin, which is subcutaneous 

 throughout its entire length. 

 To the medial side of this is 

 a smooth, slightly convex 

 surface, which reaches the 

 medial condyle proximally, 

 and distally becomes con- 

 tinuous with the medial sur- 

 face of the medial malleolus. 

 This is the medial or sub- 

 cutaneous surface of the body, 

 FIG. 248. ANTERIOR ASPECT OF THE PROXIMAL PORTIONS OF THE which is covered only by skin 



MA BIOHT LEG WI ATTACHMENTS OF MC8CLES and superficial fascia, except 



in its proximal fourth, where 



the tendons of the sartorius, gracilis, and semitendinosus muscles overlie it, 

 they pass towards their insertions. This surface is limited posteriorly by ttu 

 medial margin, which passes from the medial and distal surface of the medi* 

 condyle proximally to the posterior border of the medial malleolus distally. Tl 

 margin is rounded and indefinite proximally and distally, being usually bes 

 marked about its middle third. To the lateral side of the anterior crest is th 

 lateral surface of the bone ; it is limited behind by a straight vertical ridge, the 

 crista interossea (interosseous crest), to which the interosseous membrane, whicl 

 occupies the interval between the tibia and the fibula, is attached. This 

 commences near the middle of the lateral and distal surface of the lateral condyle 

 and terminates about two inches from the distal extremity by dividing into tw( 

 lines, which separate and enclose between them the surface for articulation wit! 

 the distal end of the fibula, and the area of attachment of the interosseom 

 ligament, which here unites the two bones. In its proximal two-thirds th< 

 lateral surface provides an extensive origin for the tibialis anterior. Distally, 

 where the anterior crest is no longer well defined, the lateral surface ' 

 forwards on to the front of the body, and is limited by the anterior margii 

 of the distal articular surface. Over this the tendon of the tibialis anterior, 

 and the combined fleshy and tendinous parts of the extensor hallucis propriuf 

 and extensor digitorum longus muscles pass obliquely distally. The posteri< 

 surface of the body lies between the interosseous crest laterally and the medi* 

 margin on the medial side. Its contours are liable to considerable variatioi 

 according to the degree of side to side compression of the bone. It is usually full 



