392 



HISTOLOGY. 



modiolus from the veins of the spiral lamina; these anastomose with the 

 spiral veins (Fig. 440). It receives branches also from the acoustic nerve 

 and from the bones, and empties "in all probability, into the vena spinalis 

 anterior." (The transverse and petrosal sinuses are often said to receive 

 this vein; and the vena aquaeductus vestibuli has been described as entering 

 the inferior instead of the superior petrosal sinus.) 



Lymphatic spaces within the internal ear are represented by the 

 perilymph spaces which communicate through the aquaeductus cochleae 

 with the subarachnoid space; the connecting structure or "ductus peri- 

 lymphaticus" is described as a lymphatic vessel. The saccus endolymph- 

 aticus which is the dilated distal end of the endolymphatic duct, is in con- 

 tact with the dura, and there are said to be openings between it and the 

 subdural space. In the internal ear perivascular and perineural spaces 

 are found, and they probably connect with the subarachnoid space. 



Cartilage. "~ ~ 



Glands, -srr^j; ~ 



Mucosa of the 

 pharynx. 



Glands. 



FIG. 441. CROSS SECTION OP THE CARTILAGINOUS PART OP THE AUDITORY TUBE. 

 (Bohm and von Davidoff.) 



X 12. 



MIDDLE EAR. 



The tympanic cavity, which contains air, is lined with a mucous 

 membrane closely connected with the surrounding periosteum. It consists 

 of a thin layer of connective tissue covered generally with a simple cuboidal 

 epithelium. In places the epithelial cells may be flat, or tall with nuclei 

 in two rows. Cilia are sometimes widely distributed and are usually to be 



