TERTIARY SYPHILIS. 31 



mentioned. Gummatous ulcerations are common in parts exposed 

 to injury and pressure, such as the tissues around the lower 

 part of the knee, on the buttocks, and over the sacrum. 



With regard to bones, the most vascular and cancellous 

 and those which are exposed to injury from their position are 

 liable to suffer. The proclivity to inflammation of the spongy 

 vascular bones of the nasal cavity, of the palate, of the vertex 

 of the skull, and even of the spinal column, is well known. The 

 tibiae and the clavicles, which are bones especially exposed to 

 injury, are prone to gummata. It is possible that the attach- 

 ment of powerful muscles to bone and periosteum may determine 

 the incidence of syphilitic nodes, for example the clavicular 

 origin of the greater pectoral, the attachment of the calf muscles 

 to the lower end of the femur, and the insertion of the masseter 

 into the mandible. The persistency of the bone pains in gum- 

 matous periostitis may be explained by the tension of the 

 resisting periosteum, whilst the pains which accompany bone 

 sclerosis are due to increasing pressure on the nerves which lie 

 in the contracting Haver sian canals. Syphilitic necrosis is 

 brought about by vascular occlusion, due to pressure and to endar- 

 teritis. The nasal deformities of syphilis are explained by the 

 destruction of the supporting bone and cartilage of the septum, 

 and in children also by retarded growth of the inflamed 

 structures. 



Bursae, by virtue of their functions, are exposed to pressure, 

 and those which are most exposed are most likely to show 

 syphilitic manifestations. In persons who kneel much the 

 prepatellar bursae may become gummatous ; in those who sit 

 much the bursae over the ischial tuberosities may become 

 similarly diseased. Other bursae likely to suffer are those about 

 the insertions of the muscles on the inner side of the leg below 

 the knee, those over the great trochanter, and the bursae between 

 the ilio-psoas muscle and the hip-joint. 



Syphilis may affect the central nervous system in various 



ways. Arterial disease, gummatous and sclerosing inflamma- 



ions of the interstitial tissues, and primary degenerations of 



