THE HAND. 365 



feeling for the upper end of the first interosseous space on the dorsum of the hand 

 and selecting a spot at a corresponding level on the palmar surface. It lies deep 

 beneath the palmar fascia and flexor tendons and nerves, and necessitates too great a 

 disturbance of the parts to expose it for ligation ; hence, when wounded, bleeding 

 from it is checked by packing the wound with antiseptic gauze. A curved line, 

 convex downward, from the radial side of the pisiform bone to the web of the thumb, 

 describes approximately the course of the superficial palmar arch. It lies immedi- 

 ately beneath the palmar fascia, and if it bleeds freely can be exposed by an incision 

 and tied. The incision should preferably be a longitudinal one to avoid wounding 

 the digital arteries and nerves. The superficial palmar arch lies superficial to the 

 tendons and they should not be disturbed. The digital nerves come down beneath 

 the palmar arch, so that they need not be wounded in ligating it. As they reach the 

 webs of the fingers the nerves become superficial to the arteries, and in the fingers 

 they lie anterior and nearer the median line. The fingers are usually supplied with 

 blood from the superficial palmar arch, and the digital arteries between the palmar 

 arch and webs of the fingers may be quite large. Sometimes the fingers are supplied 

 by large digital branches from the deep palmar arch, then those from the superficial 

 will be correspondingly small. 



In uniting the several ends of tendons the two ends of the same tendon should 

 be joined and not the flexor sublimis joined to the profundus and vice versa. 



ABSCESSES OF THE HAND AND FINGERS. 



Purulent collections in the palm of the hand are located either beneath the 

 palmar fascia or are connected with the sheaths of the flexor tendons. When the 

 fingers are affected the pus may be either in the sheaths of the tendons or in the cell- 

 ular tissue beneath the skin. 



Abscess Beneath the Palmar Fascia. As a result of infected wounds pus 

 may accumulate beneath the palmar fascia. The construction of this fascia (see 

 page 357) limits the spread of the pus in some directions and favors it in others. 

 Pus originating beneath the thick middle triangular portion will tend to point to 

 either side, and it may show on the inner side at the hypothenar eminence, or work 

 toward the outer side and point in the web of the thumb (Fig. 379). 



It may take an upward course and pass under the annular ligament to point on 

 the anterior surface of the forearm above the wrist. 



If it tends downward it escapes through the openings for the exit of the digital 

 arteries and nerves, and shows in the webs of the fingers. 



If it extends still farther it burrows between the distal extremities of the meta- 

 carpal bones and shows on the back of the hand. 



Sometimes the pus works directly toward the surface through small gaps in the 

 fascia. In such cases a small amount of pus may accumulate above the palmar fascia 

 and between it and the skin ; so that there is a collection of pus both above and 

 below the fascia, communicating through a hole in the fascia. This is called an 

 hour glass abscess, or the abces en bissac of the French. 



In opening such abscesses, if their character is not recognized the surgeon may 

 only incise the superficial of the two collections and fail to evacuate the deeper and 

 more serious one. 



In incising palmar abscesses the only safe way is to limit the incision to the skin 

 and open the deep parts by inserting a closed pair of forceps and then separating 

 its blades. Incisions should not be made nearer to the wrist than on a level with 

 the web of the thumb, or the superficial palmar arch may be cut. The spaces 

 between the metacarpal bones are occupied by the digital arteries and nerves ; hence 

 any longitudinal incisions should be made over the tendinous sheaths and metacarpal 

 bones. Usually it is not necessary to carry the incision so deep as to open the 

 sheaths. Incisions over the second, third, and fourth metacarpal bones are tolerably 

 certain to avoid the digital arteries, but an incision over the fifth is liable to wound the 

 artery going to the ulnar side of the little finger as it crosses over from the superficial 

 palmar arch. These arteries of the palm are also liable to be more or less irregular 

 in their location, hence it is better to avoid using the knife in the deeper structures. 



