368 MIDDLE EAR. 



ossicula audituSj stretching across its cavity from the mem- 

 brana tympani to the fenestra ovalis. They are four, the 

 malleus, incus, os-orbiculare, and. stapes , (Fig. 107.) 



The malleus, so called from its resemblance to a hammer, 

 is the first in order behind the membrana tympani, and is 

 FlG - 1Q7 - connected with it. It consists of a head, neck, 

 handle, a long and short process. The head 

 is situated in the depression on the upper part 

 of the tympanum, and is smooth and round 

 above, and concave below for articulating with 

 the incus. Below the head is the constricted 

 portion called the neck -from this the long and 

 short processes arise. The long one called the 

 processus gracilis or process of Kau, is a slender 

 thorn-like process, proceeding from the ante- 

 rior part of the neck. It enters the Glasserian 

 fissure, and gives attachment to the laxator tympani mus- 

 cle, which is thought to be more properly a ligament. The 

 short process is external, and rests against the upper part 

 of the membrana tympani. The handle (manubrium) de- 

 scends almost vertically from the neck, as low as the centre 

 of the membrana tympani, to the radiating fibres of which 

 it is strongly attached. 



The incus, (or anvil,) Fig. 10*7, is posterior to the mal- 

 leus, and has been, not inaptly, compared to a bicuspid 

 tooth. It consists of a body and two crura. The body re- 

 ceives the head of the malleus, and lies in the depression of 

 the tympanum. The superior or short crus proceeds horizon- 

 tally backward and is found in the opening of the mastoid 

 cells. The inferior or long crus 'descends vertically into 

 the cavity of the tympanum, having the chorda tympani 

 between it and the handle of the malleus, and terminates 

 in a hook-like process, which has on its extremity a small 

 round tubercle, the os-orbiculare. 



The Stapes, (Fig. 107,) so called from its resembling a 

 stirrup-iron, is situated between the fenestra ovalis, and the 



FIG. 107 represents the Ossicles or Little Bones of the Ear, separately and of 

 the natural size, a Malleus. 6 Incus, c Os-orbiculare. d Stapes. 



