364 HUMAN ANATOMY. 



OSSICLES OP THE TYMPANUM. 



The small bones of the tympanum are three in number, and 

 connect the membrana tympani with the membrane closing the 

 fenestra ovalis. They are the 



1. Malleus., or hammer., consists of a head, neck, manubrium 

 or handle, processus gracilis, and processus brevis. The manu- 

 brium is attached to the membrana tympani, and has the tendon 

 of the tensor tympani attached. Processus gracilis is lodged in 

 the Glaserian fissure. 



FIG. 164. 



The auditory ossicles. A. G., external meatus; M, membrana tym- 

 pani; n, handle of the malleus and its short process (p); h, head of 

 the malleus; a, incus; K, its short process, with its ligament; 1, long 

 process; s, os orbiculare; S, stapes; Ax, Ax, the axis of rotation of 

 the ossicles, shown in perspective; t, line of traction of the tensor 

 tympani. The other arrows show the movements of the ossicles when 

 the tensor contracts. (Boenning.) 



2. Incus, or anvil, consists of a body and long and short 

 processes. The body articulates with the malleus and the long 

 process by means of a rounded process. The os orbiculare ar- 

 ticulates with the head of the stapes. 



3. Stapes, or stirrup, has a head, neck, two branches (or 

 crura) which unite into a cross-piece or base. The neck has in- 

 serted into it the stapedius muscle, and the base is fitted to the 

 fenestra ovalis. 



