ANGEIOLOGY. 89 



anastomotica ; 2, the i^osterior ulnar recurrent^ wliich ascends behind the 

 inner condyle, and anastomoses with the anastomotica and inferior pro- 

 funda ; 3, the interosseal artery^ which passes backwards and divides into an 

 anterior and a posterior branch, the former going to the carpal bones and to 

 the sheaths of the extensor tendons, the latter to the extensor muscles ; 4, 

 mmcular branches to the two layers of flexor muscles and to the skin ; 

 5, dorsalis carpi ulnaris^ to the back part of the wrist and hand ; 6, superficial 

 palmar^ which forms the palmar arch, bending across the palm of the hand 

 to inosculate with branches of the radial artery ; 7, palmaris profundus^ 

 which joins the deep palmar branch of the radial artery, thus completing 

 the deej) palmar arch, 



4. The Eadial Artery continues in the direction of the brachial artery, 

 passing along the radial side of the forearm to the wrist; it then turns round 

 the external lateral ligament of this joint, and passes forwards into the palm 

 of the hand, terminating in three branches. It is accompanied by two 

 veins, and the radial nerve is at its external side in the middle of the fore- 

 arm. It passes over the biceps supinator brevis, pronator teres, flexor 

 digitorum sublimis, flexor pollicis, and pronator quadratus. 



It gives off: 1, the radial recurrent to the supinators and extensors, inos- 

 culating with the superior profunda ; 2, muscular branches^ to the flexors 

 and supinators ; 3, superficialis voice, to the small muscles of the thumb, 

 inosculating with the ulnar artery, forming the superficial palmar arch; 4, 

 dorsalis carpi radialis ; 5, dorsalis pollicis ; 0, radialis indicls ; 7, magna pol- 

 licis^ along the first metacarpal bone, and dividing into two branches ; 8, 

 palmaris profunda, which, passing across the metacarpal bones, joins the 

 deep branch of the ulnar, and thus forms the deep palmar arch, from which 

 branches proceed to the interosseal muscles, and to the bones and ligaments 

 of the metacarpus. 



PI. 134, fig. 2, arteries of the forearm and of the palm of the hand: 

 ', ulnar artery ; ^, anterior interosseal ; ', posterior interosseal ; ', superficial 

 palmar ; *, metacarpal branch ; '■ ', digital branches ; ', radial artery ; ", its 

 palmar branch ; '°, deep palmar arch ; ", branch to the back of the hand ; 

 '% an anterior branch. Fig. 6, arteries of the lower part of the forearm 

 and the back of the hand : ', branches of the external interosseal ; •', dorsal 

 branch of the radial ; ', anastomoses on the back of the hand ; \ artery of 

 the thumb ; ^, third metacarpal branch. 



D. Thoracic Aorta. 



The thoracic aorta descends obliquely forwards from the termination of 

 the arch to the diaphragm. It is inclosed in the posterior mediastinum ; the 

 root of the left lung above, the heart and pericardium in the middle, and 

 the Oesophagus with the vagal nerves below, are anterior to it. The verte- 

 bral column is behind. It gives off the bronchial, cesophageal, and inter- 

 costal arteries. 



The bronchial arteries are two or three in number. They arise from the 

 forepart of the aorta, below the arch. They pass to either side, enter the 

 back part of the root of each lung, and are lost in the cellular tissue of these 



795 



