6S 



THE SKELETON 



lic'^ paralkl Avith tlie handle of the malleus. On the inner aspect of the distal 

 t'xt remit V of this i)rocess is the orbicular tubercle, connected with the process by 

 a' narrow neck. Its free surface articulates with the head of the stapes. The 

 orbicular tubercle is separate in early life. ^ i- . i , • , ^^ 



The stapes is the innermost ossicle. It has a head directed horizontally out- 

 wards ca]n)ed at its outer extremitv by a disc resembling the head of the radius. 

 Tiie cup-sliaped depression receives the orbicular tubercle of the incus. The base 



Fig. 78.— The Bones of the Eak. (Modified from Henle.) 



LEFT MALLEUS 



FOSSA FOR INCUS 



HEAD OF MALLEUS 



SHORT PROCESS 

 SLENDER PROCESS 



HANDLE OR MANUBRIUM 



LEFT INCUS 



SHORT PROCESS 



ANTERIOR CRUS 



POSTERIOR CRUS 



— ARTICULAR SURFACE FOR MALLEUS 



ORBICULAR TUBERCLE 



BASE OF STAPES 



occupies the fenestra ovalis, and like this opening the inferior border is straight, 

 and the superior curved. The base is connected with the head by means of two 

 crura, and a narrow i)icce of bone called the neck. Of the two crura, the anterior 

 is th(! shorter and straigliter. The crura with the base form a, stirrup-shaped arch, 

 of whicli tlic inner margin presents a groove for the reception of the membrane 

 which is stretched across tlie hollow of the stapes. In the early endiryo this hollow 

 is traversed by tlie stapedial artery. The neck is very short, and receives on its 

 posterior border tlie tendon of the stapedius muscle. 



