368 



APPLIED ANATOMY. 



Bone felons are not as a rule primary in their origin, unless syphilitic in charac- 

 ter, but arise secondarily by extension from the skin above. 



LYMPHATICS OF THE HAND. 



The hand and fingers are abundantly supplied with lymphatics which begin in 

 a plexus around the matrix of the nail and the pulp of the fingers and unite to form 

 lymphatic trunks which proceed up the wrist and forearm. There are both superficial 

 and deep sets, which communicate at the wrist. 



The deep set follows the arteries of the forearm and arm to the axilla. This set 

 sometimes possesses a few nodes in the forearm and one at the flexure of the elbow. 



The superficial set, both anteriorly and posteriorly, concentrates in the supra- 

 trochlear nodes and thence proceeds to the axilla. Some of the lymphatic vessels 

 pass by the supratrochlear nodes and empty direct into the axillary nodes (Fig. 382). 



In infections of the fingers or hand the infection follows the lymphatic trunks, 

 which can be seen as red lines running up the forearm. Suppuration may involve 

 the supratrochlear and, later, the axillary nodes. As some of the lymphatic trunks 



FIG. 382. Superficial lymphatic vessels of upper limb; semidiagrammatic. (Based on figures of Sappey.) 



pass by the supratrochlear nodes to empty direct into the axillary nodes there may 

 be infection of the latter without any implication of the former. Enlargement 

 and inflammation of the occasionally present deep lymphatic nodes of the forearm is 

 clinically unknown, so it may be said that practically there are no lymphatic nodes 

 below the supratrochlear ones. 



AMPUTATIONS OF THE THUMB AND FINGERS. 



In these amputations it is particularly necessary to be able to accurately locate 

 the joints. The distal phalanx when flexed always passes under the proximal one. 

 When the flexor and extensor tendons are cut they should be sewed either to their 

 sheaths or united to one another over the ends of the bone. 



AMPUTATIONS OF THE THUMB. 



Distal Phalanx. In removing the distal phalanx the joint is opened by an 

 incision across the dorsum in a line with the middle of the side of the proximal pha- 

 lanx. A long flap is to be cut from the palmar surface. As the flexor and extensor 

 tendons are inserted into the base of the distal phalanx, it will be an advantage to 

 retain it if possible. The digital arteries may even here require ligation. 



