242 CIRCULATORY SYSTEM. 



ply the lower part of the vastus externus muscle, and others 

 the superior external portion of the knee joint. 



3. The Middle Articular Artery (*ftrt. *flrticularis Media) 

 is smaller than either of the above, and sometimes comes from 

 one of them, but generally from the popliteal, on a line with 

 the articulation of the krifce. It is distributed to the posterior 

 part of the capsular ligament, to the crucial ligaments, and to 

 the corresponding adipose matter. 



; 4. The Inferior Internal Articular Artery (Art. Articularis In- 

 ferior Internet) arises on a line with the inferior part of the 

 internal condyle, sometimes lower down. Its origin is very 

 much concealed by the internal head of the gastrocnemius; it 

 passes beneath the latter, and then between the internal lateral 

 ligament of the knee and the head of the tibia; consequently, it 

 is covered by the internal hamstring muscles. It afterwards 

 ascends towards the patella, and is distributed in numerous 

 branches to the inferior internal part of the knee joint, and to 

 the adjacent portion of the tibia. 



5. The Inferior External Articular Artery (Art. Articularis 

 Inferior Externa) arises near the last, below the 'external con- 

 dyle, being concealed by the belly of the plantaris. It passes, 

 horizontally, or nearly so, between the popliteus and the outer 

 head of the gastrocnemius, and afterwards beneath the tendon 

 of the biceps and the external lateral ligament of the joint, 

 around the external face of the head of the tibia. It gives 

 small branches to these several parts, and is then distributed, 

 by two orders of ramifications, to the superficial and to the 

 more deeply seated parts at the external inferior portion of the 

 knee joint. 



These several articular arteries anastomose freely with 

 each other, and are minutely ramified on the knee joint and 

 the contiguous structure. They also anastomose with the 

 long descending branch of the external circumflex of the thigh, 

 with the anastomotica of the femoral, and with the tibia! re- 

 current. 



