FOREARM AND HAND 113 



raised with care. More especially is it necessary to proceed with caution 

 at the roots of the fingers in order that some transverse fibres, constituting 

 a superficial cutaneous ligament, may be preserved. In reflecting the medial 

 flap of integument it is well not to lift it quite as far as the medial border 

 of the hand, because it is into this portion of skin that the m. palmaris 

 brevis is inserted. 



Superficial Structures. The superficial fascia over the 

 central part of the palm is dense and thin, and the fat is 

 subdivided into small lobules by fibrous septa which bind 

 the skin to the subjacent palmar aponeurosis. Towards the 

 medial and lateral margins of the hand the fat becomes softer, 

 and the amount of fibrous tissue amongst it diminishes. 

 In connection with the superficial fascia of the palm we have 

 to study (i) the palmaris brevis; (2) the superficial trans- 

 verse ligament ; and (3) the palmar cutaneous nerves. 



The m. palmaris brevis is a small cutaneous muscle embed- 

 ded in the superficial fascia which covers the proximal part of 

 the hypothenar eminence. If it has not already been exposed 

 by the reflection of the skin, carry the knife transversely 

 through the granular fat on the ulnar margin of the palm 

 immediately below the transverse carpal ligament. The fleshy 

 bundles of the muscle will come into view. When these 

 have been cleaned, the muscle will be seen to consist of a 

 series of distinct fasciculi, which, in its distal part, are 

 frequently separated from each other by intervals of varying 

 width. It constitutes a thin fleshy layer, which covers an 

 inch and a half or more of the hypothenar eminence. 

 Laterally it takes origin from the transverse carpal ligament 

 and medial border of the intermediate part of the palmar 

 aponeurosis whilst medially its fasciculi are inserted into the 

 skin over the medial margin of the hand. 



The volar (palmar) cutaneous nerves are three in number, and 

 they arise, as already noted, from the ulnar and median 

 nerves and from the superficial branch of the radial nerve. 

 They should now be traced to their ultimate distribution in 

 the palm of the hand. 



The transverse superficial ligament is a band of fibres which 

 extends across the palm at the roots of the fingers. It is 

 intimately connected with the skin, and is enclosed within the 

 folds of integument in the clefts between the fingers. 



Dissection. The palmaris brevis should be reflected by detaching its 

 fasciculi from their origin, and turning them medially. In raising the 

 muscle care must be taken of the ulnar artery and nerve, which lie under 

 VOL. I 8 



