36 CLINICAL APPLIED ANATOMY. 



instances of so-called senile gangrene, where, however, arterial 

 disease is usually present, and perhaps more typically in 

 that symmetrical peripheral gangrene known as Eaynaud's 

 disease, in both cases the smaller arterioles and capillaries are 

 obstructed by clot following stasis. Senile gangrene begins 

 almost always at the extreme periphery of the lower extremity, 

 namely, in the toes. These are the farthest off of any part from 

 the heart, and a slight traumatism, such as the cutting of a corn 

 or the pressure of an ill-fitting boot, determines a lessening 

 of resistance which, with the poor circulation, induces death of 

 the area. 



Eaynaud's disease is most frequently seen at the end of the 

 upper extremity in the finger s\ parts which, although nearer the 

 heart than the toes, are perhaps more frequently exposed from 

 their uncovered condition to the effects of cold. So also are the 

 tips of the ears and the nose, which may likewise suffer in this 

 disease. 



The gangrene induced by frost-bite is due to the cessation of 

 circulation in the terminal vessels, and again is seen almost 

 entirely in the extreme peripheral parts, and particularly those 

 subjected to most exposure the toes, fingers, ears and nose. 



The loss of large quantities of blood may so retard the circula- 

 tion that gangrene may result in the extremities, and for the same 

 reason, when the carotid artery is tied after severe haemor- 

 rhage hemiplegia from anaemia of brain tissue is to be expected. 



The second anatomical consideration is that parts exposed to 

 pressure, especially if that pressure be long continued, are 

 extremely liable to necrosis. Inflammatory exudations under 

 firm fasciae and under the periosteum of bones may give rise to 

 sufficient pressure to induce gangrenous or necrotic processes. 

 It is from pressure that bedsores occur over bony points in patients 

 who have to remain in one position for some length of time. 

 Pressure sores may also be caused by the application of a splint 

 not sufficiently padded, where it comes in contact with bony 

 points. In association with this may be mentioned the not very 

 infrequent occurrence of a sore at the posterior part of the heel 



