316 SPECIAL ANATOMY. 



major, below teres minor, behind os humeri. Branches to the articular 

 capsule, periosteum, and m. deltoideus. 



564. Brachialis, the Brachial artery. 

 Continuation of axillaris, reaches as far as the fore-arm, where 



it bifurcates. Course : extends downwards first on the internal, 

 then on the anterior surface of the upper arm, so that it is situated 

 in front of the elbow-joint in the centre of the flexure. Situation : 



565. 1. In the upper arm : 



covered in front and above by m. coraco-brachialis, then by the 

 internal border of m. biceps; behind and above by m. triceps, then 

 by brachialis inter nus ; internally by fascia brachialis and skin; 

 externally accompanied by m. coraco-brachialis and the internal 

 surface of the Humerus ; in a common sheath with n. medianus. 

 Vv. brachiales lie on both sides ; N. medianus above on the out- 

 side, in the middle in front, below on the inner side ; N. cubitalis 

 above on the inner side ; N. radialis behind the brachial artery. 



566. 2. In the flexure of the arm : 



separated before by v. mediana, aponeurosis bicipitis from the skin ; 

 behind by m. brachialis internus from the joint ; on the inside of 

 the tendon of m. biceps ; on the outside of the n. medianus and 

 m. pronator teres. 



Branches sixteen to twenty ; external anterior for mm. coraco- 

 brachial., biceps, brachial. intern., and deltoid; internal posterior 

 for m. brachial. internus. 



Nutritia humeri arises from a muscular branch, or from profunda brachii, 

 enters into the foramen above the centre on the inner side of the humerus. 

 Also the following : 



1. Profunda brachii. Or.: often in common with circumfl. poster., on the 

 inferior border of teres major. Course : downwards and backwards, close to 

 2V. radial., round the posterior circumference of os humeri, in a groove which 

 it abandons under the attachment of m. deltoid., and divides into a deep and 

 superficial branch. Situation : between os humeri and m. triceps, then between 

 triceps and brachial intern. Branches: 



a. Collateralis radialis profunda, accompanying the n. radialis, between 

 cap. intern, and extern, tricipitis ; supplies these ; anastomoses with 2. 



b. Collateralis radialis superficial passes directly downwards along the lig. 

 intermuscl. extern, behind the condyl. extern, and anastomoses with a. re- 

 currens radialis. 



2. Collateralis ulnaris superior (prima), [s. profunda inferior] arises close 

 next to or from the profunda brachii, passes downwards on the inner side of 



