DISSECTING MANUAL. 



processus lenticularis. The neck, internal to the head, is con- 

 stricted; it receives the Stapedius tendon posteriorly. The 

 two crura spring from the neck, diverge, and are attached near 

 the ends of the footplate. The footplate is oval, or reniform 

 in shape. [756] 



Ligaments of the Ossicles. Malleus: The anterior is in 

 two parts; one runs from the base of the long process, through 

 the Glaserian fissure, to the spine of the sphenoid; the other 

 runs from above the long process to the anterior end of the 

 notch of Rivinus. The superior ascends from the head to the 

 roof of the epitympanic recess. The external runs from the 

 crista to the posterior half .of the notch of Rivinus. Incus : 

 The posterior fastens the tip of the short process in the fossa 

 incudis. Stapes : The annular runs from the edge of the foot- 

 plate to the edge of the fenestra ovalis. [757] 



Intrinsic Muscles of the Tympanum. 



Tensor Tympani. Origin; roof of cartilaginous part of 

 Eustachian tube; adjacent part of great wing of sphenoid; 

 walls of its bony canal. Insertion ; inner surface and anterior 

 edge of handle of malleus, near its upper end, by a tendon which 

 bends at right angles around the posterior extremity of the 

 processus cochleariformis. [757] 



Stapedius. Origin ; inner surface of pyramid and canal pro- 

 longing it downward. Insertion; posterior surface of neck of 

 stapes. [757] 



THE INTERNAL EAR. 



Osseous Labyrinth. This series of intercommunicating 

 cavities in the petrous bone consists, from before backward, 

 of the cochlea, vestibule, and semicircular canals. [759] 



The vestibule is an ovoid cavity behind the cochlea; its 

 outer wall presents the fenestra ovalis. Its inner wall cor- 

 responds with the bottom of the internal auditory meatus and 

 presents the following structures: A depression (recessus 



[100] 



