ANATOMY IN A NUTSHELL. 



569 



municates with the naso-pharynx by means of the Eustachian tube, (b) the 

 mastoid antrum, (c) the mastoid cells, (b) and (c) are accessory air chambers 

 to the tympanum. 



3. The internal ear or labyrinth, contains the membranous labyrinth 

 which is a cast of the bony structures. The membranous labyrinth contains 

 the endolymph, and within it are the specialized neuro-epithelial cells and the 

 terminations of the auditory nerve. The perilymph is on the outside of the 

 membranous labyrinth. 



The External Ear. 



The pinna is the projecting part of the ear lying outside of the head, and is 

 attached to the malar and temporal bones by ligaments. It consists of a layer 

 of yellow fibro-cartilage covered with integument. It has the following parts. 



PLATE CCLXXXVII. 



FOSSA FOR INCUS 



ARTICULAR SURFACE FOR MALLEUS 



LEFT MALLEUS 



SHORT PROCESS 



ANTERIOR CRU3 



BASE- 



POSTERIOR CRUS 



HEAD OF MALLtUS 



SHORT PROCESS 

 — SLENDER PROCESS 



HANDLE OR MANUBRIUM 



BASE OF STAPES 



Malleus, [ncus and Stapes. 



1. The helix is the outer curved edge of the pinna which passes upward 

 from the rim of the pinna and ends behind in the lobule. 



2. The lobule is the lowest portion of the auricle and consists of fatty and 

 areolar tissue. 



3. The fossa of the helix (scaphoid ibssa) is a depression internal to the 

 helix. 



4. The antihelix is a range which begins above the Lobule .-u the anti- 

 tragus and passing upward bifurcates to enclose a triangular depression called 

 the fossa of the antihelix. 



