40 



SUPERFICIAL ANATOMY OF THE UPPER LIMB. 



less regular lines, representing the folds or " flexures " produced in the skin by the 

 movements of the principal joints of the hand. Two of these lines are directed 

 nearly transversely, the others longitudinally. Of the transverse lines, one 

 commences about the junction of the upper three-fourths with the lower fourth of 

 the inner border of the palm, and runs outwards and then downwards to the cleft 

 between the index and middle fingers ; this is caused by bending the metacarpo- 

 phalangeal articulations of the inner three fingers ; the second starts nearly opposite 

 the foregoing, at the outer border of the hand, and is directed inwards and sorne- 



SUPtRFICIAL 

 ARCH 



Fig. 18. PALMAR SURFACE OF THK HAND, SHOWING THE CUTANEOUS LINES AND THE SITUATION OF 



THE CHIEF ARTERIES IN RELATION TO THE SKELETON. (G. D. T. ) 



what upwards across the middle of the palm ; this results mainly from the flexion of 

 the first joint of the index finger. The metacarpo-phalaugeal articulations are 

 placed about midway between these lines and the web of the fingers. Of the 

 longitudinal lines, one, beginning near the centre of the wrist, curves outwards to 

 join the upper transverse line, and is produced by the opposition of the thumb ; the 

 other runs downwards from the wrist through the centre of the palm to meet the 

 lower transverse line opposite the middle finger, and is caused by the opposition of 

 the fifth metacarpal bone. The four lines give rise to a figure resembling the 

 letter M. At the wrist, two or three lines, directed rather obliquely, outwards and 

 a little downwards, indicate the position of the principal folds formed during flexion 



