290 CIRCULATORY SYSTEM, 



The Deep Seated Absorbents of the head have been followed 

 to the membranes of the brain, but not farther. Ruysch ob- 

 served them between the tunica arachnoidea and the pia mater, 

 inflated with air, and called them vasa pseudo-lymphatica. Lan- 

 cisius, Pacchuni, and others, assert their having found them in 

 the pia mater. Doubts, however, are cast upon these several 

 observations, owing to such vessels not having been injected 

 with quicksilver, and from the want of a valvular appearance in 

 them; also from the want of lymphatic glands in the brain. 

 Their existence, however, would seem to be sufficiently proved, 

 both from general analogy, and from affections of the brain 

 producing swellings in the glands of the neck. On the dura 

 mater they have been traced along the course of its arteries, 

 They descend from the interior of the cranium into the neck, 

 along the carotid and vertebral arteries. The absence of 

 lymphatic glands in the cranium may be accounted for from 

 the fact, that the ready tendency of these organs to swell upon 

 slight causes of irritation, would have rendered the individual 

 liable to death, from compression of the brain, by their tume- 

 faction. Mr. Cruikshank has found lymphatic glands in the ca- 

 rotid canal. 



The Deep Lymphatics of the face, as those from the interior 

 of the nose, of the orbit, of the tongue and mouth, attend the 

 arteries which respectively supply those parts. 



These several absorbents, from the surface and from the in- 

 terior of the head, descend to the base of the cranium, and then 

 begin to pass through the chain of lymphatic glands situated 

 along the course of the great blood vessels of the neck. They 

 lie, for the most part, under the sterno-mastoid muscle, and, 

 when successfully injected, are thought to form the most bril- 

 liant plexus of absorbents in the whole frame. On each side 

 of the neck, one or more common trunks are, at length, formed; 

 that on the left side joins the Left Thoracic Duct near its ter- 

 mination, while the one on the right assists in forming the duct 

 peculiar to that side, the Right Thoracic Duct, or, more pro- 

 perly called, the right Brachio Cephalic. 



The lymphatic vessels of the muscles of the neck, and those 

 of the thyroid gland, enter ioto the trunks of the neck. Ac- 

 cording to Mr. Cruikshank, those of the thyroid gland may be 



