BRANCHES OF THE THORACIC AORTA. 331 



The Common interosseous artery is a short trunk which arises from 

 the ulnar, opposite the bicipital tuberosity of the radius. It divides 

 into two branches, the anterior and posterior interosseous arteries. 



The Anterior interosseous passes down the fore-arm upon the inter- 

 osseous membrane, between the flexor profundus digitorum and flexor 

 longus pollicis, and, behind the pronator quadratus it pierces that 

 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 connection 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 superfi- 

 cial palmar arch. 



The Posterior interosseous artery passes backwards through an 

 opening between the upper part of the interosseous 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 profunda. 



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 

 anterior 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 between the heads of the metacarpal bones, and form the colla- 

 teral 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 superficialis vola3 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 

 frequent variety. 



BRANCHES OF THE THORACIC AORTA. 



Bronchial, 



CEsophageal, 



Intercostal. 



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



