158 SPECIAL SENSES. 



with the malleus, and, by the extremity of its long process 

 (B, 2, Fig. 11), with the stapes. The stapes (C, Fig. 11) is 

 the most internal bone of the middle ear. It is articulated 

 by its smaller extremity with the long process of the incus. 

 Its base is oval (C*, Fig. 11) and, with its annular ligament, 

 is applied to the f enestra ovalis. The direction of the stapes 

 is nearly at a right angle with the long process of the incus 

 in the natural state (8, Fig. 12). 



There are three well-defined muscles connected with the 

 middle ear. Of these, two are attached to the malleus, and 

 one, to the stapes. 



The largest of the three muscles is the tensor tymparii, 

 called sometimes the internal muscle of the malleus. Its 

 fibres arise from the cartilaginous portion of the Eustachian 

 tube, the spinous process of the sphenoid bone, and the adja- 

 cent portion of the temporal. From this origin, it passes 

 backward, almost horizontally, to the tympanic cavity. In 

 front of the f enestra ovalis, it turns, nearly at a right angle, 

 over a bony process, and its tendon is inserted into the han- 

 dle of the malleus at its inner surface near the root. The 

 tendon is very delicate, and the muscular portion is about 

 half an inch in length (10, Fig. 10). The muscle and its 

 tendon are enclosed in a distinct fibrous sheath. The action 

 of this muscle is to draw the handle of the malleus inward, 

 pressing the base of the stapes against the membrane of the 

 fenestra ovalis, and producing tension of the membrana tym- 

 pani. The fibres of this, and of all the muscles of the ear, 

 are of the striated variety. The tensor tympani is supplied 

 with motor filaments from the otic ganglion, which are prob- 

 ably derived from the facial nerve. 1 



The laxator tympani, the external muscle of the malleus, 

 arises from the spinous process of the sphenoid bone and, by 

 a few filaments, from the cartilaginous portion of the Eusta- 

 chian tube. It passes backward, through the Glasserian fis- 

 sure, to be inserted into the neck of the malleus, being en- 



1 See vol. iv., Nervous System, p. 420. 



