ii2 , THE UPPER EXTREMITY 



whilst the transverse elevation above the roots of the fingers, 

 which corresponds to the metacarpo-phalangeal articulations, 

 constitutes the distal boundary of the central palmar depres- 

 sion. Two pronounced bony projections on the front of the 

 wrist cannot fail to attract attention when the hand is bent 

 backwards. The more prominent of the two is situated at 

 the proximal extremity of the thenar eminence, and is formed 

 by the tubercle of the navicular bone and the vertical ridge on 

 the front of the os multangulum majus ; the other is placed at 

 the proximal end of the hypothenar eminence, and is some- 

 what obscured by the soft parts attached to it. It is caused 

 by the pisiform bone, and when taken firmly between the 

 ringer and thumb a slight degree of gliding movement can 

 be communicated to it. Traversing the thick integument of 

 the palm, three strongly marked furrows are apparent. One 

 of these begins at the elevation formed by the navicular and 

 os multangulum, and curves distally and laterally, around the 

 base of the thenar eminence, to the lateral margin of the 

 hand. A second crosses the palm transversely. Commenc- 

 ing at the middle of the lateral border of the hand, where the 

 first furrow ends, it runs medially, but, as a general rule, it 

 fades away upon the hypothenar eminence. The third 

 furrow begins near the cleft between the index and middle 

 fingers, and proceeds medially with a gentle curve across 

 the hypothenar eminence to the medial margin of the hand. 

 The transverse cutaneous furrows at the roots of the fingers, 

 and on the palmar aspects of the interphalangeal joints, should 

 also be noticed. The furrows at the roots of the fingers are 

 placed over the palmar aspects of the proximal phalanges 

 very nearly one inch distal to the metacarpo-phalangeal joints. 

 The proximal of the two furrows palmar to each of the 

 proximal interphalangeal joints is placed immediately over 

 the articulation, whilst in the case of the distal inter- 

 phalangeal joints the single crease which is usually present 

 is situated immediately proximal to the articulation. On 

 the back of the hand the metacarpal bones can be readily 

 felt, whilst their distal extremities, or heads, form the promin- 

 ences known as the "knuckles." 



Reflection of Skin. In the first instance the skin should only be raised 

 from the palm. Two incisions are required viz. (i) a vertical incision 

 along the middle line of the palm ; (2) a transverse cut across the roots of 

 the fingers from the medial to the lateral margin of the hand. The skin is 

 tightly bound down to the subjacent palmar aponeurosis, and it must be 



