218 VISCERAL ANATOMY. 



Annular Ligament, connecting the base of the stapes to the margin of the 

 fenestra oval is. 



Capsular Ligaments, around the articulations between the ossicles them- 

 selves, which articulations are lined by synovial membranes, with articular 

 cartilages between the contiguous surfaces. 



Name the Muscles of the Tympanum. Three are usually described, 

 the Tensor Tympani, Laxator Tympani, and the Stapedius. A fourth, the 

 Laxator Tympani Minor, is now generally omitted, being considered the 

 posterior ligament of the malleus by most writers. Many otologists omit 

 die Laxator Tympani from the list also. [These muscles are described on 

 page 7 1.] 



What Arteries supply the Tympanum ? The 



Tympanic, branch of the internal maxillary, entering the Glaserian fissure, 

 anastomosing on the membrana tympani, in a vascular circle, with the Stylo- 

 mastoid and Vidian arteries, and the Tympanic br. of the internal carotid. 

 Stylo-mastoid, br. of the posterior auricular br. of the external carotid, en- 

 tering at the stylo-mastoid foramen. 



Petrosal, br. of middle meningeal artery, entering by the hiatus Fallopii. 

 Tympanic, br. from the internal carotid artery. (See p. 105.) 

 Vidian, br. of the internal maxillary br. of the external carotid. 

 Branches, from the ascending pharyngeal br. of the external carotid. 



Name the Nerves of the Tympanum. The 



Tympanic Br. of the Glosso-pharyngeal (Jacobson's Nerve) , enters the tym- 

 panum through its floor, and supplies the two fenestrae and the mucous lin- 

 ing of the cavity, helping to form the Tympanic Plexus (see below). 



Tympanic Branch of the Facial Nerve, to the stapedius and laxator tympani 

 muscles. 



Branch from the Otic Ganglion, to the tensor tympani muscle. [This 

 ganglion is described on page 137.] 



Chorda Tympani Br. of the Facial, enters the tympanum by the iter chordae 

 posterius, crosses the cavity between the handle of the malleus and the long 

 process of the incus, and makes its exit by the iter chordce anterius, after 

 passing close along the upper part of the membrana tympani. 



How is the Tympanic Plexus Formed ? By the 



Tympanic Br. of the Glosso- Pharyngeal, or Jacobson's nerve. 



Branch of the Superficial Petrosal, from the Facial, entering from above. 



Branches from the Carotid Plexus of the Sympathetic, through the wall 

 of the carotid canal. 



The plexus lies in grooves on the inner wall around the promontory, and sup- 

 plies the mucous membrane of the tympanum. 



