ORGANS OF SPECIAL SENSE. 365 



Ligaments of the Ossicles: 



Lig. mallei anterius, extends from the neck of the malleus to the 

 outer wall of the tympanum; 



Lig. mallei suspensorium, suspends the head of the malleus to the 

 roof; 



Lig. incudi posticum, attaches the short process to the posterior 

 wall ; 



Lig. incudi suspensorium, suspends the incus to the roof; 



Lig. stapedi annularum, connects the base to the margin of the 

 fenestra ovalis. 



Muscles. The tensor tympani, stapedius. 



Tensor tympani (already described). 



Stapedius arises from the hollow of the pyramid on the inner 

 wall, and its tendon is inserted into the neck of the stapes. 

 Nerve from the tympanic branch of facial. 



Arteries: 



Tympanic branch of internal maxillary; 

 Stylo-mastoid branch of posterior auricular; 

 Petrosal branch of middle meningeal; 

 Tympanic branch from internal carotid; 

 Branch from ascending pharyngeal. 



Veins accompany the corresponding arteries and empty into 

 middle meningeal and pharyngeal. 



Nerves: 



Chorda tympani, from the facial, enters the iter chorda 

 posterius, crosses the tympanum between the long process of the 

 incus and the handle of malleus, and makes its exit at the iter 

 chords anterius; 



Tympanic branch of glosso-pharyngeal (Jacobson's nerve) 

 enters the floor, supplies the fenestrae and mucous membrane of 

 tympanum and Eustachian tube; 



Tympanic branch from facial to the stapedius ; 



Branch from the otic ganglion to the tensor tympani. 



The tympanic plexus is formed upon the surface of the 

 promontory, from the following nerves : 



Jacobson's nerve, tympanic branch of the glosso-pharyngeal j 

 Branch of the superficial petrosal, from the facial ; 

 Branches from the carotid plexus of the sympathetic. 



INTERNAL EAR, OR LABYRINTH. 



The internal ear, the essential part of the organ of hearing, 

 consists of three complex cavities within the petrous portion of 

 the temporal bone, filled with fluid, the perilymph, and contain- 



