TYMPANIC OSSICLES. yall 
seu anterior, (0) processus brevis seu lateralis. The head and neck are situated in 
the epitympanic recess; the processus brevis and manubrium are fixed to the inner 
surface of the membrana tympani; whilst the processus longus is directed forwards 
Recessus epitympanicus 
q Body of ineus 
Short process of incus~ — Superior ligament of malleus 
: 3 : Head of malleus 
Ligament of ineus—— = 
ZS, a 
= a . . y 
e c 2S Ap ~~ Anterior ligament of malleus 
Chorda tympani nerve — a* & 
. c "GC aol Ge 
Pyramid, with tendon * & & ane 
of stapedius muscle—_ = ry “Demy Handle of malleus 
issuing from it QD 
ae Tensor tympani muscle 
_ Processus 
Foot of stapes cochleariformis 
Osseous part of 
Eustachian tube 
Fie. 520.—LEFT MEMBRANA TYMPANI AND CHAIN OF TYMPANIC OSSICLES (seen from inner aspect). x 3. 
towards the Glaserian fissure, to which, in the adult, it 1s connected by ligamentous 
fibres. The head, somewhat rounded, is smooth and convex above and in front, and 
presents, on its posterior aspect, a facet for articulation with the body of the incus. 
This facet is directed obliquely downwards and inwards, and reaches slightly on to 
its mesial surface. More or less elliptical in form, it is constricted near the middle 
so as to resemble, somewhat, a figure of 8: an oblique ridge, corresponding with the 
constriction, divides the facet into two parts—an upper and larger, directed back- 
wards; and a lower and lesser, directed inwards. Opposite the lower part of the 
constriction the inferior edge of the facet is very prominent, and is continued up- 
wards into the oblique ridge, just referred to; it forms a tooth-like process, the spur 
or cog-tooth of the malleus. On the back of the head, below this spur, is an oblique 
crest, the crista mallei, to which is attached the posterior ligament of the malleus. 
The neck is the slightly-constricted portion immediately below the head. Flattened 
from before backwards, its outer surface is directed towards the membrana flaccida, 
whilst its inner is crossed by the chorda tympani nerve. The handle is directed 
downwards, inwards, and backwards from the neck, forming with the long axis of 
the head an angle, opening inwards, of 126° to 150°. Its upper part is flattened 
from before backwards, but towards the lower end it is twisted on itself, so that its 
surfaces look outwards and inwards; moreover, the lower end is slightly curved, 
the concavity being directed forwards and outwards. It is fixed, along its entire 
length, to the membrana propria of the tympanic membrane by its periosteum and 
by a layer of cartilage (Gruber). This latter intervenes between the handle and 
the membrane, and must be regarded as a residue of that stage of development when 
the entire malleus was cartilaginous. On the inner aspect of the handle, near its 
upper extremity, a slight projection for the attachment of the tendon of the tensor 
tympani muscle may be seen. The long process is a slender spicule springing from 
the forepart of the neck and directed forwards towards the Glaserian fissure. In 
the foetus it constitutes the longest process of the malleus and is directly continuous 
with Meckel’s cartilage. In the adult it usually assumes the form of a small pro- 
jection, since its anterior part is represented merely by fibrous tissue. The short 
process may be looked upon as the upper extremity of the handle projected out- 
wards ; it is fixed to the upper part of the membrana tympani by the cartilaginous 
layer already referred to, and to the extremities of the notch of Rivinus by the 
anterior and posterior malleolar folds. 
The incus (Fig. 519 A, C) may be best likened to a bicuspid tooth, with widely 
