308 BRANCHES OF THE THORACIC AORTA. 



The Anterior interosseons passes down the fore-arm upon the intercsse- 

 ous membrane, between the flexor profundus digitorum and flexor longus 

 pollicis, and behind the pronator quadratus. In the latter position it 

 pierces the interosseous membrane, and descends to the back of the wrist, 

 where it inosculates with the posterior carpal branches of the radial and 

 ulnar. It is retained in connexion with the interosseous membrane by 

 means of a thin aponeurotic arch. 



The anterior interosseous artery sends a branch to the median nerve, 

 which it accompanies into the hand. The median artery is sometimes of 

 large size, and occasionally takes the place of the superficial palmar arch. 



The Posterior interosseous artery passes backwards through an opening 

 oetween the upper part of the interosseods membrane and the oblique 

 ligament, and is distributed to the muscles on the posterior aspect of the 

 fore-arm. It gives off a recurrent branch, which returns upon the elbow 

 between the anconeus, extensor carpi ulnaris and supinator brevis muscles, 

 and anastomoses with the posterior terminal branches of the superior pro- 

 funda. 



The Muscular branches supply the muscles situated along the ulnar 

 border of the fore-arm. 



The Carpal branches, anterior and posterior, are distributed to the an- 

 terior and posterior aspects of the wrist joint, where they inosculate with 

 corresponding branches of the radial artery. 



The Digital branches are given off from the superficial palmar arch, and 

 are four in number. The first and smallest is distributed to the ulnar side 

 of the little finger. The other three are short trunks, which divide be- 

 tween the heads of the metacarpal bones, and form the collateral branch 

 of the radial side of the little finger, the collateral branches of the ring and 

 middle fingers, and the collateral branch of the ulnar side of the index 

 finger. 



The Superficial palmar arch receives the termination of the deep palmar 

 arch from between the abductor minimi digiti and flexor brevis minimi 

 digiti near their origins, and terminates by inosculating with the superfi- 

 cialis volae upon the ball of the thumb. The communication between the 

 superficial and deep arch is generally described as the communicating 

 branch of the ulnar artery. 



The mode of distribution of the arteries to the hand is subject to fre- 

 quent variety. 



BRANCHES OF THE THORACIC AORTA. 



Bronchial, 



CEsophageal, 



Intercostal. 



The BRONCHIAL ARTERIES are four in number, and vary both in size 

 and origin. They are distributed to the bronchial glands and tubes, and 

 send branches to the oesophagus, pericardium, and left auricle of the heart. 

 These are the nutritious vessels of the lungs. 



The CESOPHAGEAL ARTERIES are numerous small branches ; they arise 

 from the anterior part of the aorta, are distributed to the oesophagus, and 

 establish a chain of anastomoses along that tube : the superior inosculate 

 with the bronchial arteries, and with cesophageal branches of the inferior 



