LYMPHATICS OF THE MOUTH 



715 



canal of the nervous sj-stem, and which is to be considered as a zone in which the 

 tissue-spaces are especially large. Along the arteries of the brain the adventitia is 

 loose and open, possessing tissue-spaces which have received the confusing name of 

 perivascular lymphatics. It would be better to name them perivascular tissue- 

 spaces. 



The lymphatics of the eye. — No lymphatic vessels have as yet been discovered 

 either in the eyeball or in the orbit. In both, however, there are abundant tissue- 

 spaces, the most noteworthy of the orbit being the interfascial space (space of 

 Tenon), which communicates by a space between the optic nerve and its sheath 

 with the subarachnoid spaces of the cranial cavity. In the eyeball the tissue- 

 spaces are abundant, even if the vitreous and aqueous chamber be omitted from 

 the category. Numerous spaces exist in the chorioid coat, especially in the lamina 

 supra-chorioidea, and in the sclerotic, both sets communicating by perivascular 

 spaces surrounding the venae vorticosaj with the interfascial space. In the cornea 

 there are abundant lacunae, united b}' their anastomosing canaliculi, to form a 

 network of lymph-spaces which come into close relation with the conjunctival 

 lymphatics at the corneal margin. 



Fig. 560. — The Deep Cervical Chain. (After Poirier.) 



Collectors of fossa of 

 auricle 



Mastoid nodes 



Sterno-mastoid node 

 (.external group) 



Node of external 



jugular chain 



Internal jugular chain 



Node draining the sub- 

 mental node 



The conjunctiva, being a portion of the integument, does possess lymphatic 

 vessels Cfig. 562) , arranged in a double network whose collecting vessels accompany 

 those of the eyelids, and terminate with them in the submaxillary, anterior 

 auricular, and parotid nodes. 



The Lymphatics of the Digestive Tract in the Head and Neck 



The lymphatics of the gums. — The lymphatics from the mucous membrane 

 of the gums pass to the submaxillary nodes. The capillary plexus is abundant; 

 the collecting vessels arise from it on the inner surface of the gum, and pass 

 between the teeth to reach a common semicircular collecting vessel on the outer 

 surface. Lymphatics have recently been demonstrated in the pulp of the tooth 

 (Schweitzer). 



The lymphatics of the tongue. — There is a rich lymphatic plexus throughout 

 the entire extent of the submucosa of the tongue, but that portion lying in the 

 basal part of the tongue seems to be more or less independent of the rest. Accord- 

 ing to Aagaard the tongue muscles are provided with h^mphatics which are drained 

 by the ducts of the submucosal plexuses. There are four groups of collecting 

 vessels — (1) apical; (2) marginal; (3) basal; and (4) central. 



(1) The apical vessels axe usually four in number, two on each side. One pair perforates 

 the mylo-hyoid muscle and ends in a supra-hyoid median node, while the other pair pass to 

 the deep cervical chain. The latter are long, slender vessels, which run along the frenum of 

 the tongue to the surface of the mylo-hj^oid muscle, cross the hyoid bone just behind the pulley 

 of the digastric, and then run downward in the neck to a node of the deep cervical chain, just 



