MORBID ANATOMY 



137 



ii III. Morbid 

 anatomy. The usual 

 direct ana t o m i c a 1 

 changes following the 

 invasion of tubercle 

 bacteria are the forma- 

 tion of nodules or 

 tubercles. A tubercle 

 has been defined as, 

 "a small nonvascular 

 nodule compose d o f 

 cells varying in form 

 and size with some 

 basement substa nee 

 between the m a n d 

 with an inherent ten- 

 dency to undergo 

 central necrosis. " In 

 a large number of 

 cases the individual 



Fig. 24. RiffhUatenii aspect 0/ posterior 



tubercles are distinct /'(^if "/ steer's head, (a) lower Jaw. (b) ear 



and easily recogniz- 

 able while in others 

 thev are coalesced 



passage. [c] horn, id] styloid process of 

 occipital bone, (e) parotid gland. {/) siih- 

 ina.villary gland. A. right parotid lymph 

 gland. B. right post maxillary lymph 

 forming a mass of gland. C. right submaxillary lymph gland. 

 necrotic tissue. The I -yniph glands often the seat of tubercular de- 

 lesions vary, there- P°'"^'- ^Smith.) 



fore, from well isolated minute or larger nodules to masses or 

 cavities containing a purulent, caseous, or calcified substance. 

 The location of the primary lesion depends upon the chan- 

 nel of infection. If the specific organisms are lodged in the 

 oral cavity or pharynx the^' may, through an accidental abra- 

 sion of the mucosa, be taken to some of the lymphatic glands 

 about the head ; if they are taken directly through the respira- 

 tory passages into the lungs they either develop nodules in the 

 lung tissue proper, or they are carried through the lymphatic 

 system to the lymph glands draining the lungs where the lesions 

 first appear. If the specific bacteria are first lodged in the 



Digitized by Microsoft® 



