THE KNEE-JOINT 



291 



Passing backward from the capsule on each side of the patella is a prominent crescentic 

 fold formed by reduplications of the synovial membrane — these are the alar folds (fig. 322). 

 Their free margins are concave and thin, and are lost below in the patellar fold. There is a 

 slight fossa above and another below each ligament. 



Fig. 322. — Anterior View of the Knee-joint, showing the Synovial Ligaments. 

 (Anterior portion of capsule with the extensor tendon thrown downward.) 



Posterior crucial ligament 



Patellar fold 



Alar fold 



Alar fold 



Synovial pouch under tendon of 

 quadriceps femoris 



Fig. 323. — The Upper Extremity of the Tebia (Posterior View), to show the Relation 

 OF the Articular Capsule of the Knee-joint (in red) to the Epiphysial Line. 



The arterial supply is derived from the art. genu suprema (anastomotica); the superior and 

 inferior medial and lateral articular; the medial articular; the descending branch of the lateral 

 circumflex; the anterior recurrent branch from the anterior tibial; and the posterior tibial 

 recurrent. 



