90 THE EAE. 



by a longitudinal groove into secondary facets. The inferior margin of the articular 

 surface is very prominent opposite the constriction, and forms here, in fact, the 

 lower end of the ridge above mentioned (spur of the malleus}. Below the head 

 is a constricted neck (d) ; and beneath this another slight enlargement of the bone, 

 to which the processes are attached. The handle (manubrium) (m), the lower 

 tapering point of the malleus, is slightly twisted, and is compressed from before 

 backwards to near its point, where it is flattened laterally. It forms a rounded 

 obtuse angle with the head of the bone (fig. 97 B), and passes downwards with an 

 inclination forwards and inwards, on the inner side of the membrana tympani, to 

 which it is closely attached both by its periosteal covering and. also by a layer of 

 cartilage extending its whole length, and especially marked at the attachment of the 

 processus brevis. The point of insertion of the tendon of the tensor tympani muscle 

 is sometimes marked by a slight projection on the inner side of the manubrium near 

 its upper end. The long process (processus gracilis vel Folianus) (fig. 97 B, pr. (jr.) 

 is a very slender spiculum of bone, which in the adult is usually converted, except 

 a small stump, into ligamentous tissue, and even where it still exists as bone is often 

 broken off in its removal from the tympanum ; it projects at nearly a right angle 

 from the front of the neck of the malleus, and extends thence obliquely downwards 

 and forwards to the Glaserian fissure. Its end is flattened and expanded, and is 

 connected by ligamentous fibres or bone to the sides of the fissure. In the foetus 

 this process is directly continued into Meckel's cartilage (see Vol. I, Part I, p. 168). 

 The short process (processus brevis vel obtusus) (b) is a low conical eminence situated 

 at the root of the manubrium, beneath the cervix, and projecting outwards towards 

 the upper part of the membrana tympani, to which it is attached. 



The incus (fig. 98), as its name implies, has been compared to an anvil ; but it 

 resembles perhaps more nearly a tooth with two fangs widely separated. It consists 



Fig. 98. LEFT INCUS, VIEWED FROM THE INNER SIDE AND SOMEWHAT 

 FROM BEFORE. Magnified four times. (GK D. Thane.) 



b, body ; a m. ridged articular surface for the malleus ; pr. br, 

 processus brevis ; I. ?', rough surface near its extremity for the 

 , attachment of the ligament of the incus ; pr. I, processus longus, 



terminating below in a small projection which comes off from it at a 

 right angle, and is capped by a convex tubercle, processus lenticularis, 

 p7*o CB) pv- v, for articulation with the stapes. 



of a body and two processes. The body has a deep saddle-shaped articular surface 

 in front (a.m\ which fits over the articular surface on the head of the malleus, and 

 which consists, like that of the malleus, of two chief facets, each subdivided to form 

 two secondary facets. The lower margin of the articulation is excavated to receive 

 the spur-like prominence of the malleus, and in front of this excavation is very 

 prominent, where it also forms a spur, against which that of the malleus catches in 

 inward movements of the manubrium. The shorter process (cms breve) (pr.br.) of 

 the incus projects backwards. Its extremity is tipped with cartilage, and is 

 moveably articulated by ligamentous fibres with the posterior and partly with the 

 outer wall of the tympanum near the entrance to the mastoid cells. The place 

 where the ligamentous fibres are attached to the wall of the tympanum is somewhat 

 depressed, and has a covering of cartilage. The long process (crus longum) 

 (pr.l.) tapers rather more gradually, and passes downwards and inwards parallel 

 to the handle of the malleus, and about 1| mm. mesial to and behind it. At 

 its extremity it is bent inwards at an angle which varies considerably in different 

 bones, and is suddenly narrowed into a short neck ; and upon this is set a flattened 

 tubercle (pj'ocessus orbicular is seu lenticularis) (pr. o.), tipped with cartilage. This 

 tubercle, which articulates with the head of the stapes, was formerly, under the name. 



