THE EAR 233 



The handle: a long tapering process passing downward, 

 and attached by its outer side to the membrana tympani. 



The processus gracilis : a slender spicule passing from the 

 neck downwards and forwards into the Glaserian fissure. 



The processus brevis : arises from the root of the handle and 

 projects outwards to be attached to the membrana tympani 

 by the anterior and posterior malleal folds which bound the 

 notch of Rivini. 



The incus, or anvil, consists of : 



The body : articulating in front by a saddle-shaped facet 

 with the head of the malleus. 



The processus brevis : attached to the margin of the mastoid 

 aditus. 



The processus longus : passes downwards, behind and parallel 

 to the handle of the malleus. The tip projects inwards, 

 and ends in the orbicular process, which articulates with the 

 head of the stapes. 



The stapes closely resembles a stirrup. It consists of: 



The head: looking outwards, and articulating with the 

 orbicular process of the incus. 



The base : fixed to the margins of the fenestra ovalis. 



The crura : arising from a constricted part, the neck, pass 

 inwards to the extremities of the base. The anterior crus is 

 shorter r-xd straighter than the posterior, and between the 

 two a th.n membrane is stretched. 



The ligaments unite the chain of bones to the adjacent 

 walls of the tympanum. They are : 



The anterior ligament of the malleus : passing between the 

 root of the processus gracilis and the edge of the Glaserian 

 fissure. This ligament was formerly described as a muscle 

 passing from the malleus out of the Glaserian fissure, and 

 termed the laxator tympani. 



The external ligament of the malleus : passing between the 

 processus brevis and notch of Rivini. 



The superior ligament of the malleus : passing between the 

 head of the malleus and the roof of the tympanum. 



The ligament of the incus : passing between the processus 

 brevis and the posterior wall of the tympanum. 



The annular ligament of the stapes connects the base of the 

 stapes with the edge of the fenestra ovalis. 



The muscles : 



The tensor tympani arises from cartilage of the Eustachian 

 tube, and from the bony canal in which it lies. The tendon 

 turns round the end of the processus cochleariformis, and 

 is inserted into the inner border of the handle of the malleus, 

 near its root. 



