246 SURGICAL APPLIED ANATOMY. [Chap. xv. 



that lies deeply beneath the flexor tendons, and covers 

 in the interossei muscles, the bones, and the deep 

 palmar arch. This fascia joins on either side the 

 fasciae enclosing the thenar and hypothenar " spaces " 

 (Fig. 27). 



In opening a palmar abscess, when it points above 

 the wrist, the incision should be in the long axis 

 of the fore-arm, should be above the annular ligament, 

 and is most conveniently made a little to the ulnar 

 side of the palmaris longus, for a cut in this position 

 would escape both the ulnar and radial arteries and 

 also the median nerve. 



The tendons about the wrist are bound down and 

 held in place by the annular ligaments. So dense 

 is the anterior ligament, that even in extensive abscess 

 of the palm reaching into the fore-arm, and in severe 

 distension of the sy no vial sheaths beneath the liga- 

 ment, it remains firm, and will not yield. The 

 lower border of the posterior annular ligament 

 corresponds to the upper edge of the anterior band, 

 and these structures together act the part of the 

 leather bracelet that the labourer sometimes wears 

 around his wrist, and that, in fact, takes the function 

 of an additional annular ligament. 



The fit>roiis slieatlis for the flexor tendons ex- 

 tend from the metacarpo-phalangeal joints to the upper 

 ends of the third phalanges. The pu]p of the third 

 phalanx, therefore, rests practically upon the perios- 

 teum. Opposite the finger joints the sheaths are lax 

 and thin, and spaces may occur between the decussat- 

 ing fibres of the sheaths, through which the synovial 

 membrane lining the sheath may protrude. It is, I 

 believe, through this less protected part of the sheath 

 that suppuration without often finds its way into the 

 interior of the sheath. The sheaths in the rest of 

 their course are dense and rigid, and when cut across 

 remain, in virtue of this rigidity, wide open (Fig. 



