THE HAND. 41 



of the joint ; the radio-carpal articulation is placed about three-quarters of an inch 

 above the lowest of these lines. There are three well-marked transverse grooves on 

 each finger ; the lower and middle ones are nearly opposite the two interphalangeal 

 joints ; the upper one, which is produced, as well as the transverse lines of the palm, 

 by bending the metacarpo-phalangeal articulations, is placed nearly three-quarters of 

 an inch (15 mm.) below the joint, and on a level with the web of the fingers. On the 

 thumb, there are only two grooves, and the proximal, which is less distinct than the 

 other, continues upwards the line of the radial border of the index finger, thus 

 crossing obliquely the corresponding articulation. 



The web of the fingers, containing the superficial transverse ligament, limits the 

 interdigital clefts on the palmar side ; on the dorsum of the hand the clefts are 

 continued upwards almost to the metacarpo-phalangeal joints. 



The superficial palmar arch is placed beneath the palmar fascia about the centre 

 of the palm ; its position may be indicated by a line carried from the outer 

 side of the pisiform bone downwards, and then curving outwards across the 

 middle third of the palm on a level with the upper end of the cleft between the 

 thumb and index finger. From the convex side of the arch digital branches 

 proceed, one to the ulnar margin of the little finger, and three which descend 

 opposite the intervals between the fingers and bifurcate about half an inch above 

 the clefts. The deep palmar arch rests against the metacarpal bones about a quarter 

 of an inch nearer the wrist than the superficial arch, and the digital branches given 

 off by the radial artery to the thumb and index finger are deeply placed in the 

 palm, the collateral arteries of the thumb becoming superficial at the base of the 

 first phalanx, that of the index finger issuing from behind the adductor transversus 

 pollicis. The latter branch is not unfrequently derived from the radial artery at 

 the back of the wrist, and may then be felt pulsating as it descends on the posterior 

 surface of the abductor indicis muscle to its destination. The superficial volar 

 artery is occasionally visible as it descends over the upper part of the thenar to 

 the palm. 



