86 TOPOGRAPHIC AND APPLIED ANATOMY. 



FIG. 37. The muscles, nerves, vessels, and tendon-sheaths of the palm of the hand. The tendon-sheaths are 

 colored blue. The carpal canal has been opened by dividing the anterior annular ligament. 



FlG. 38. Diagrammatic representation of the joints of the hand. 



digitorum and of the extensor indicis; (5) for the tendon of the extensor minimi digiti; and (6) 

 for the tendon of the extensor carpi ulnaris. The second and third compartments are frequently 

 combined to form a single sheath. 



The anterior annular ligament connects the eminentia carpi radialis with the eminentia 

 carpi ulnaris and forms the roof of the carpal canal. This canal transmits the flexor tendons of the 

 fingers (flexor sublimis and profundus digitorum and flexor longus pollicis) and the median nerve, 

 which pass into the palm of the hand. The median nerve lies upon the tendons immediately 

 beneath the ligament. The ulnar nerve and artery, however, pass into the hand over the anterior 

 annular ligament to the radial side of the pisiform bone. At the lower end of the radius, distal 

 to the insertion of the supinator longus, the radial artery passes from the flexor to the extensor 

 side, between the styloid process of the radius and the scaphoid bone. It passes beneath the 

 tendons of the extensor ossis metacarpi pollicis and extensor brevis pollicis into the tabatiere or 

 "snuff-box" (see page 85), and then runs beneath the tendon of the extensor longus pollicis to 

 reach the space between the first two metacarpal bones. The vessel then leaves the back of the 

 hand and passes into the palm between the heads of the first dorsal interosseous muscle. During 

 this course the radial artery, in addition to branches to the rete carpi dorsale and -volare [that is, 

 the vascular network on the dorsal and palmar surfaces of the wrist. ED.], gives off two 

 vessels which vary considerably in size : 



1. The superficialis voice, which is often absent, though frequently as large as the continuation 

 of the radial. It leaves the radial at the styloid process of the radius and passes over the origins 

 of the short muscles of the thumb to unite with the ulnar artery and form the superficial palmar 

 arch. This branch is covered only by the skin and a thin fascia (and sometimes also by a few 

 slips from the muscles of the thumb), and, when well developed, is a dangerous vessel on account 

 of its exposed position. In some individuals its pulsations may be seen through the skin. 



2. The prince ps pollicis, which passes between the muscles of the ball of the thumb to the 

 palmar surface and gives off three digital branches to supply both sides of the thumb and the 

 radial side of the index-finger. 



The terminal portion of the radial artery anastomoses with the deep branch of the ulnar and 

 forms the deep palmar arch, which is situated upon the bases of the metacarpal bones. This arch 

 gives off the palmar interosseous arteries, which are usually small in size and pass distally between 

 the bases of the first phalanges to empty into the digital branches of the superficial arch. If the 

 superficial arch and some or all of its digital branches are poorly developed, the palmar inter- 

 osseous arteries are larger and furnish the digital arteries for the fingers. 



The ulnar artery, in contrast to the radial, always remains upon the flexor side of the forearm. 

 After giving off the anterior and posterior carpal branches, it passes over the anterior annular 

 ligament to the radial side of the pisiform bone. In the palm of the hand it gives off a deep 

 branch and then unites with the superficialis volae from the radial to form the superficial palmar 

 arch, which is situated immediately beneath the palmar fascia. From the superficial palmar arch 



