BRANCHES OF THE BRACHIAL. PECULIARITIES. 386 



directed to the back part of the iuner condyle of the humerus. Descending 

 in company with the uluar nerve, it pierces the intermuscular septum, theu 

 lies on the inuer surface of the triceps muscle, to which it gives branches, 

 and entering the interval between the olecranon and inner coudyle, it 

 terminates by inosculating with the posterior recurrent branch of the uluar 

 artery, and with the anastomotic branch of the brachial. 



(c) The nutrient artery of the shaft of the humerus is a small branch 

 giveu off by the brachial about the middle of the arm, or by one of its 

 collateral branches. It inclines downwards, enters the oblique canal in the 

 humerus near the insertion of the coraco-brachialis muscle, and is distributed 

 in the interior of the bone. 



(d) Ttie anastomotic artery (collateralis nlnaris secunda) is a very con- 

 stant branch of moderate size. Arising from the brachial artery about two 

 inches above the bend of the arm, it is directed transversely inwards on the 

 brachialis anticus muscle, above the inner condyle of the humerus, and, after 

 perforating the intermuscular septum, turns outwards behind the humerus, 

 between the bone and the triceps muscle, and forms with the superior pro- 

 funda an arch across the humerus, immediately above the olecranou fossa 

 (arcus dorsalis humeri posticus, Haller). In front of the humerus the 

 anastomotic artery furnishes a branch which ramifies in the pronator teres, 

 and anastomoses with the anterior ulnar recurrent branch. Behind the 

 inner condyle another offset joins with the posterior ulnar recurrent, and 

 behind the humerus several branches are given to the joint and the muscle. 



PECULIARITIES. From their comparative frequency, and surgical interest, the 

 peculiarities of the brachial artery, especially those which affect its trunk, deserve 

 particular attention. 



Course. The brachial artery sometimes lies in front of the median nerve, instead 

 of behind it. 



The brachial artery has been seen, though rarely, to descend, accompanied by the 

 median nerve, towards the inner condyle of the humerus, and regain its usual position 

 at the bend of the elbow by passing forwards underneath a fibrous arch, from which 

 the pronator teres in those cases arises, and which descends to the inner condyle from 

 the occasional prominence called the supracondyloid process, as has been previously 

 described (p. 80). Sometimes this disposition occurs without the development of any 

 bony prominence. 



As an extremely rare condition, the artery has been found divided into two vessels 

 near its commencement, the artery being single above and below, as also occurs with 

 the femoral trunk. 



In a very few cases the three arteries of the fore-arm, radial, ulnar, and inter- 

 osseous, have arisen together from the end of the brachial trunk, at the usual distance 

 below the elbow. 



High division. The most frequent change from the ordinary arrangement of the 

 brachial artery is connected with its division into terminal branches. 



Out of 481 examples recorded by Richard Quain from observations made, some on 

 the right and some on the left side of the body, the vessel was found in 386 to divide 

 at its usual position, a little below the elbow-joint. In one case only (and that com- 

 plicated by another peculiarity, viz., the existence of a vas aberrans proceeding from 

 the axillary to the radial), was the place of division lower than usual, being between two 

 and three inches lower than the elbow-joint. In 64 cases the brachial artery divided 

 above the usual point, at various heights upwards to the lower border of the axilla. 

 The branch prematurely separated from the rest of the trunk in an early division, is, 

 in the proportion of nearly three cases out of four, the radial artery ; sometimes the 

 ulnar is the branch given off; that is to say, a branch corresponding to the ulnar in 

 its distribution below the middle of the fore-arm separates from a trunk which after- 

 wards divides into the normal radial artery and the interosseous of the fore-arm, 

 which last is normally derived from the ulnar artery. Rarely the interosseous of the 

 fore-arm, or a vas aberrans } is the branch given off. 



