518 THE ABSOEBEXT VESSELS. 



some of the vessels passing through one or two glands usually found 

 near the zygoma, whilst others enter those situated on the parotid 

 gland ; all of them terminate in the lymphatic glands of the neck. 

 The cranial lymphatics of the occipital set, accompanying the occipital 

 artery, descend to the glands situated behind the ear, on and near the 

 mastoid process of the temporal bone, and hence join the superficial 

 lymphatics of the neck. 



"Within the cranial cavity, lymphatic vessels have been demonstrated 

 in the pia mater and in the arachnoid membrane. Distinct vessels 

 have not been traced in the dura mater, nor have they been shown in 

 the substance of the brain. The trunks of those derived from the pia 

 mater pass out of the skull with the veins. 



In the substance of the brain and spinal cord, according to the observations of 

 Robin and of His, i)fr'n-a!<cidiir spaces or canah suiTound all the bloodvessels, 

 even to their capillary ramifications, and are in communication with similar 

 spaces and lymphatic vessels in the pia mater, and, acco^xling to Axel Key and 

 Retzius, they may be injected from the svibarachnoid spaces. The delicate walls 

 of these perivascular canals agree in their histological character \\ith those of the 

 capillary Ijinphatic vessels, and their cavity is filled with a clear Ij-mph-like fluid, 

 containing numerous lymph corpuscles (Robin, in Journ. de la Physiol., 1859, 

 p. 5.37 ; and His, in Zeitsch. fur Wissensch. Zool., vol. xv. p. 127. See also 

 Vol. II. p. 572, of this work.) 



The superficial lymphatics of the face, more numerous than 

 those of the cranium, descend obliquely in the course of the facial vein, 

 and join the submaxillary glands, from six to ten in number, which are 

 placed beneath the base of the lower maxillary bone ; a few of them in 

 their descent pass through some glands situated on the buccinator 

 muscle. The deciJ lymphatics of the face, derived from those of the 

 temporal fossa and the cavities of the nose, mouth, and orbit, proceed, 

 outwards in the course of the internal maxillary vein ; and, having 

 reached the angle of the jaw, they enter the glands in that neigh- 

 bourliood. 



