ARTICULATIONS. 



facets on the tibia ; and also between the femoral trochlear sur- 

 face and the patellar. Besides hinge motion, the tibia rotates 

 slightly in extreme flexion. The capsule consists of strong 

 special bands with intervals between them, which are filled by 

 a capsular membrane consisting largely of f ascial and tendinous 

 expansions; it is absent above under the Quadriceps extensor 

 tendon. The expansions are derived anteriorly (lateral patellar 

 ligaments) from the fascia lata and Vasti tendons, on either 

 side of the patella and ligamentum patellae; internally from 

 the Sartorius and Semi-membranosus tendons ; externally from 

 the ilio-tibial band; and posteriorly from the Semi-membrano- 

 sus tendon. [297] 



The anterior ligament, or ligamentum patellae, is a strong flat 

 band running from the tubercle of the tibia to the apex and 

 adjoining margins of the patella. It acts as the Quadriceps 

 extensor tendon and some fibres cover the front of the patella. 

 A bursa separates it from the tibial tubercle; above this it 

 rests on the infra-patellar fat pad. The posterior ligament is 

 attached above to the popliteal surface of the femur, and the 

 condyles just above their articular areas; and below to the 

 posterior border of the tibial head, presenting an opening ex- 

 ternally for the Popliteus tendon. It is thin laterally but thick- 

 ened mesially by an expansion (ligamentum posticum Win- 

 slowii) of the Semi-membranous tendon; this runs obliquely 

 upward and outward to lose itself in the capsule, but may 

 present upper and lower arcuate borders between the femoral 

 condyles. [299] 



The internal lateral ligament is a strong flat band consisting 

 of two parts, which arise close together from the internal con- 

 dyle just below the adductor tubercle. The short (posterior) 

 portion descends slightly backward to the postero-internal 

 aspect of the tibia, just above the groove for the Semi-mem- 

 branosus tendon. The long (anterior) portion descends 

 slightly forward, over the Semi-membranosus tendon, to the 

 tibia just below the level of its tubercle. The ligament adheres 



[261] 



