304 POSTERIOR AND ANTERIOR TIBIAL ARTERIES. 



external circumflex, while its inferior ramifications communi- 

 cate with those of the corresponding artery below. 



The two inferior arteries originate nearly opposite to the 

 middle of the joint and pass downwards. 



The Inferior Internal artery passes under the internal head 

 of the gastrocnemius muscle, on the posterior and internal side 

 of the head of the tibia. Its ramifications communicate with 

 those of the corresponding aTtery above and of the tibialis 

 antica below. They also extend to the interior of the joint. 



The Inferior External artery passes under the external head 

 of the gastrocnemius and the plantaris muscle, and continues 

 under the external lateral and capsular ligament. It is distri- 

 buted on the external and inferior part of the articulation, and 

 sends also some branches to the interior of the joint. 



There is frequently an azygos vessel, called the Middle 

 Articular artery, which arises from the back of the popliteal, 

 and is distributed to the posterior part of the articulation. 



The Popliteal artery after this, sends off a few small branches 

 to the heads of the muscles of the leg, and among them one of 

 considerable length, to each of the heads of the gastrocnemii. 

 At the under edge of the popliteus muscle, it sends off horizon- 

 tally a large branch, which passes directly forward between the 

 tibia and the fibula, above the commencement of the interosse- 

 ous ligament. After this, it continues to descend, nearly in the 

 same direction, under the soleus muscle, behind the tibia ; but 

 before it has proceeded farther than twelve or fifteen lines, it 

 sends off a branch which forms an acute angle with it ; and 

 approaches near the fibula, along which it descends. 



The branch sent off anteriorly, is called the Anterior Tibial 

 artery. 



The main trunk, which continues downwards, is called the 

 Posterior Tibial artery ; 



And the branch which descends near the fibula is called the 

 Peroneal or Fibular artery. 



The Anterior Tibial Artery, (Tibialis Antica.) 

 After its arrival on the anterior part of the leg, passes down 



