276 THE INTEROSSEAL ARTERY. 



the internal condyle, and between the flexor sublimis and the 

 flexor profundus. Before the Ulnar Recurrent goes off from 

 this vessel, the interosseal artery often leaves it. This recur- 

 rent artery passes upwards between the muscles of the inter- 

 nal condyle, and distributes branches among them. It then 

 passes up in the groove behind the internal condyle, and anas- 

 tomoses with the branches of the Anastomotica or Profunda 

 Humeri. 



The ulnar and interosseal arteries separate from each other 

 at the distance of fifteen or twenty lines from the origin of the 

 radial artery, very near the commencement of the interosseal 

 ligament. 



The Interosseal Artery, , 



In a majority of cases, arises in a single branch from the 

 common trunk of the ulnar and interosseal. When it does so, 

 the single branch soon sends off the Posterior Interosseal artery, 

 which perforates the interosseous ligament, and passes down 

 on its posterior surface, while the main branch continues on 

 the anterior surface of the ligament, and is denominated the 

 Anterior Interosseal Artery. In some cases, the main branch 

 proceeds on the anterior surface as low as the upper edge of 

 the pronator quadratus muscle, before it sends off the poste- 

 rior branch. Sometimes the anterior and posterior interosseals 

 arise separately. In this case the posterior soon perforates the 

 ligament. 



The Anterior Interosseal passes down almost in contact with 

 the ligament, and gives branches to the contiguous parts in its 

 course. It generally perforates the interosseous ligament near 

 the wrist, and sends off many small branches to the back of 

 the wrist and hand, which anastomose with the small branches 

 of the radial and the posterior interosseal arteries. 



The Posterior Interosseal soon gives off a recurrent or anas- 

 tomosing branch, and then proceeds downwards towards the 

 wrist, sending branches in its course to the extensor muscles and 

 tendons. 



This vessel sometimes divides into two branches. 



