THE UPPER LIMB 367 



FRONT OF THE WRIST AND PALM. 



Landmarks. — Below, and internal to, the styloid process of the 

 radius the tuberosity of the scaphoid can be felt, and below this the 

 tuberosity of the trapezium. On the inner aspect of the front of the 

 wrist the pisiform bone can easily be felt, and below, and external to, 

 it, the hook of the unciform bone. The interval between these two 

 projections indicates the position of the ulnar vessels and nerve. 

 The centre of the palm presents a triangular hollow, the apex of 

 which is directed upwards and inwards towards the wrist, and the 

 base downwards towards the roots of the fingers, in which latter 

 situation there is a transverse prominence, broken up by grooves 

 leading to the four inner digits. The palmar hollow is bounded 

 above and externally by the thenar eminence, and internally by 

 the hypo thenar eminence. 



The integument of the palm presents four furrows, two being 

 disposed transversely, and two more or less longitudinally. The 

 lower transverse furrow is about i inch above the roots of the inner 

 three digits, and is most conspicuous when the fingers are flexed. 

 It commences at the inner border of the palm, and, passing outwards 

 in a slightly arched manner, it terminates at the cleft between the 

 index and middle fingers. It is produced by the flexion of the 

 me tacarpo- phalangeal joints of the inner three fingers. These 

 joints are situated about midway between this line and the roots of 

 the fingers when these are extended. The upper transverse furrow 

 commences at the outer border of the palm about f inch above 

 the root of the index finger, and it passes inwards and slightly 

 upwards to the inner border of the palm, lying about ^ inch above 

 the lower furrow. The outer part of this furrow is due to flexion 

 of the metacarpo-phalangeal joint of the index finger, and the 

 remainder to complete flexion of the metacarpo-phalangCcJ joints of 

 the inner three fingers. One of the longitudinal furrows commences 

 about the centre of the wrist, and curves downwards and outwards 

 to meet the upper transverse furrow. It is produced by flexion of 

 the joint between the trapezium and metacarpal bone of the thumb 

 during the movement of opposition. The other longitudinal furrow 

 runs downwards from the wrist internal to the preceding, and meets 

 the lower transverse furrow. It is due to the movement of opposi- 

 tion of the little finger. The front of each of the four inner fingers 

 presents three transverse furrows. The distal pair correspond 

 with the interphalangeal joints, but the proximal furrow is about 

 \ inch beyond the metacarpo-phalangeal joint. The front of the 

 thumb presents only two transverse furrows. 



The position of the superficial palmar arch corresponds with a line 

 drawn across the palm from the web between the thumb and index 

 finger (the thumb being abducted) to the outer side of the pisiform 

 bone. This line is slightly arched, with the convexity towards the 

 fingers. From the convexity of the arch the three compound 



