PALM OP THE HAND. 155 



the ulnar artery. At the anterior border of the adductor 

 pollicis, the radialis indicia communicates with the superfi- 

 cial palmar arch. The continuation of the radial artery 

 is called the deep palmar arch ; it extends across the inter- 

 osseous muscles and the metacarpal bones to the little 

 finger, where it anastomoses with the deep communicating 

 branch of the ulnar artery. The arch sends off recurrent 

 branches, which pass backward to the carpus, and perforat- 

 arteries, which penetrate the interosseous muscles to 

 >in the interosseous arteries on the back of the hand, 

 dually there are, also,, three palmar interosseous arteries 

 rich pass forward and unite with the digital arteries of 



superficial arch at the cleft of the fingers. 

 Although the distribution of the arteries of the hand, 

 lich has been described, is the one considered normal, it 

 to be remembered that " it is not possible to know, before 

 hand is opened, in what manner the arteries are distri- 

 ited. m Sometimes the radial furnishes the superficial 

 arch, and sometimes there is no arch at all ; the arrange- 

 ment is extremely irregular, and the dissector must be pre- 

 pared to find a very different arrangement from that 

 scribed. 



The deep branch of the ulnar nerve accompanies the 

 leep palmar arch across the metacarpal bones to the mus- 

 cles of the thumb, and terminates in branches to the adduc- 

 tor pollicis, the inner head of the short flexor, and the 

 abductor indicis. 



The PALMAR INTEROSSEOUS MUSCLES are three in num- 

 ber, and are placed upon, rather than between, the meta- 

 carpal bones. The first arises from the second metacarpal 

 bone, and is inserted into the ulnar side of the first phalanx 

 and extensor tendon of the forefinger ; the second arises 

 from the fourth metacarpal bone, and is inserted into the 

 radial side of the first phalanx and extensor tendon of the 

 ring-finger; the third arises from the metacarpal bone of 

 the little finger, and is inserted into the radial side of the 

 first phalanx and extensor tendon of the little finger. 



The interosseous and lumbricales muscles being sup- 

 posed to convey to the hand that peculiar dexterity and 

 delicacy of use which is found only in certain professions 

 or individuals, the dissecting-room is not the place to find 

 them in their fullest degree of development. 



1 Horner. 



