THE EAR 391 



at their extremities by the base, which fills up the fenestra 

 ovalis. 



The articulations between the several bones are provided 

 with synovial membranes; their surfaces are covered with 

 cartilage and are connected by capsular ligaments. The 

 following ligaments connect the bones with the walls of the 

 tympanum : 



The anterior ligament of the malleus is attached to the neck 

 of the malleus at one end, and at the other to the anterior wall 

 of the tympanum close to the Glaserian fissure, and its sus- 

 pensory ligament runs from the roof of the tympanum to the 

 head of the bone. An external ligament runs from the notch 

 of Rivini to the body and lesser process, and the accessory 

 anterior ligament is the thickened front portion of the sheath 

 of the tensor tympani, which runs from the anterior wall to 

 the manubrium and neck. An inferior ligament runs from the 

 end of the handle to the outer wall of the tympanum. 



The base of the stapes is fixed to the margin of the fenestra 

 ovalis by an annular ligament. 



The incus is provided with a posterior ligament, running 

 from the short process to the posterior wall, and a suspensory 

 ligament, from the roof of the tympanum to the upper part 

 of the bone near its articulation with the malleus. 



The Muscles of the Middle Ear. The tensor tympani runs in 

 the canal previously mentioned. Arising from the under surface 

 of the petrous portion, the cartilage of the Eustachian tube, 

 and the margins of its own canal, its tendon is reflected over 

 the processus cochleariformis and is inserted into the handle 

 of the malleus near its root. It pulls on the malleus, thus 

 drawing inward and making tense the membrana tympani. 

 Its nerve comes from the otic ganglion. 



The stapedius arises from the sides of its containing cavity 

 within the pyramid, and, emerging from the apex, is inserted 

 into the neck of the stapes. It draws the head of the stapes 

 backward, thus pressing the base against the fenestra ovalis 

 and compressing the contents of the vestibule. Its nerve is 

 the tympanic branch of the facial. 



The mucous membrane of the tympanum is pale and thin 

 and its epithelium ciliated. It invests the contents of the 

 cavity, the inner surface of the membrana, and covers the 

 fenestra rotunda. It is continuous with that of the mastoid 

 cells, Eustachian tube, and pharynx. 



