130 
NATURE 
| Dec. 7, 1882 
It was in endeavouring to trace the co: nection between 
these events, of no very uncommon occurrence, that I 
was led to the discovery of a most important factor in the 
physiology of the ear, and one which gives a rew and 
more rational significance to the mechanism of the ossi- 
cles and membrane. In the shape of anatomical details 
I have nothing new to adduce, but in exhibiting the re- 
lationship of a series of minute particulars hitherto 
enigmatical and glanced at separately and only casually 
by anatomy, I have obtained a valuable result for otology. 
I must here present those details in the order most con- 
venient for a brief demonstration, giving only the main 
features. 
The membrana tympani, though but a single mem- 
brane, consists of two portions. The lower is firm and 
transparent, and of conical shape, being attached along 
its centre to the handle of the malleus, and fixed round 
its whole circumference to the sulcus tympanicus. The 
upper is comparatively loose, and much less transparent, 
and being in reality mainly fastened to the skin of the 
upper wall and only slightly to the bone, there being here 
no sulcus, but only a smooth margin (margo tympan‘cus), 
is easily displaced with a little gentle pressure outwards 
or inwards. Between the two there is a line of dense 
fibres forming a ligament, called by Helmholtz the ante- 
rior ligament of the membrane, and towards the anterior 
border of which the short process of the malleus is in- 
serted. With this marked limiting line there is thus a 
striking difference in the character and mode of attach- 
ment of the two portions of membrane, and this reaches 
to the very foundations of the structures, and is the most 
remarkable feature in their development. It is to be 
remembered that the superior arch of bone, forming at 
its inner end the tympanic margin alluded to, is part of 
the squamous bone, which is characterised by the general 
smoothness of its surface—a character it preserves along 
the whole upper wall of the osseus meatus, not excepting 
its termination at the porus acousticus externus, where it 
presents a smooth bevelled edge. But the os tympanicum 
which forms the inferior arch of bone is contradistin- 
guished by the general unevenness or asperity of its sur- 
face, nct only being hollowed out by the sulcus at its inner 
end, but along the whole floor, maintaining a roughness 
which culminates in its rugged edge at the porus externus. 
Nature, in constructing the meatus, selects one bone for 
its smoothness, another for its roughness, and the evi- 
dent intention is, that what is laid on the one surface 
shall adhere, what is laid on the other shall ylide over it. 
While, therefore, the lower portion of the drum of this 
ear is fixed by its connection with the os tympanicum, the 
upper portion is loosely connected with the os squamo- 
sum, which affords it a movable surface. Helmholtz 
believes that the lower firm portion is alone concerned 
with sound-waves, the upper lying above the handle of the 
malleus, and having therefore no direct connection with 
the chain of ossicles. (Cn this ground, in his treatise on 
the mechanism of the membrane and ossicles, he leaves 
the membrana flaccida out of consideration altogether, and 
no physiologist, as far as I am aware, has ever hinted at 
its function. Having from the foregoing description ob- 
tained an insight into its relation with the bone, it must 
now be viewed in connection with the skin lining the 
upper wall of the pzssage, which is quite distinct in 
character from that covering the rest of the osseous 
passage, and next needs to be specially noticed. 
Prof. Henle says : “ The skin which covers the external 
meatus has originally the appearance and structure of the 
cutis, and retains this character along the upper wall 
beyond the vownded rim of the squamous bone which 
helps to complete the porus acousticus externus up to the 
site of the membrane, whereas in the rest of the circum- 
ference the skin, in passing from the cartilaginous to the 
osseous meatus, abruptly changes its character, decreas- 
ing in thickness and assuming the peculiar silvery glance 
of a fibrous skin.” Thus along the whole passage the 
skin on the upper wall retains its ordinary character, 
being elastic and movable, and having, as noticed by 
Von Fréitsch, the same kind of loose connective tissue 
glands and hair cysts as any other part, whereas the 
movability of the remaining portion ceases with the carti- 
laginous meatus, as beyond that it ceases to be true 
cskin.? Add to this that the one lies on a roughened, the 
other on a smooth surface, and this singular deviation in 
apparently so simple a matter and in so minute a particu- 
lar, must strike the examiner as significant of purpose. If 
we next turn to the arrangements at the porus acousticus 
externus, it becomes manifest. 
What is noticeable in regard to the rim of bone consti- 
tuting the porus is simply corroborative of what has 
already been said. Thus, whereas the under semicircle 
is comparatively rough and uneven, and projects slightly 
beyond the upper semicircle, the latter has a smooth- 
rounded edge bevelled in the manner of bone over whose 
margin a tendon plays. It is to the curved uneven 
lamella of the under circumference known as the auditory 
process that the cartilaginous meatus is principally 
attached. This is effected by means of strong, slightly 
movable ligamentous tissue, or rather, as Henle puts it, 
“by means of a compact cartilaginous substance richly 
interspersed with elastic ligamentous tissue, which fills 
up the rough interspaces of the lamella and extends the 
lower portion of the osseous canal about two milli- 
meters.’ The upper semicircle, on the contrary, is 
closed simply by a dense fibrous membrane, there being 
here a large deficiency of cartilage (Quain). The differ- 
ence is that while below the osseous canal blends in- 
sensibly into the cartilaginous with only dawning facility 
for movement, above it terminates abruptly, admitting 
there and then a large measure of movement. 
Thus then it appears that from the membrana flaccida 
of the membrane, which is easily movable at its margin, 
we have a piece of movable skin running over a smooth 
folished surface along the whole upper meatus of 
the bone, which is here bevelled off, and is immediately 
continuous with the movable membranous roof of the 
cartilaginous portion of the external passage. The 
movable piece of skin serves, after its manner, the pur- 
pose of a tendon, and the muscle which mainly plays 
upon it is attached to this upper membranous wall at its 
point of junction with the osseous meatus. 
Cf this muscle Henle gives the following account :— 
‘Of the lateral portion of the musculus epicranius (occi- 
pito-frontalis), the musculus epicranius temporalis is a 
very thin bundle of fibres, and is anterior to and smaller 
than the attollens auriculam, which forms the remainder 
of the lateral portion. It has its tendinous origin below 
the root of the zigoma, near the rim of the osseous canal, 
to the capsule of the inter-articular cartilage (operculum 
cartilagineum), and to a tendinous arch through which 
the vasa tempora'ia pass into the deep structures. Its 
muscular fibres spread out in parallel lines forwards and 
upwards, some of them stretching to the border of the 
frontalis, and of the orbicularis oculi, and so partly curving 
upwards around the lateral border of the frontalis, and 
intérmixing with the uf per fibres of the orbicularis, they 
are finally inserted into the glabella.” + 
It will thus be observed that, when the muscle con- 
tracts, it raises the membranous roof of the canal up- 
wards and slightly forwards, making the movable patch 
of skin glide outwards, and so telling upon the membrana 
flaccida, which is, even in the adult, almost in a line with 
the upper wall, and is therefore so much the more easily 
influenced by such a movement. When the delicacy of 
the parts concerned are borne in mind, it will be obvious 
that no extensive movement is thus indicated, and in a 
«« Anatomie des Menschen,”’ Z, B. s. 7 
x 2. 
2 ** Diseases of the Ear,’’ Roosa’s Teanlation; Dp. 53- 
3 Loc. cit. p. 722. 4 Loc. ctt., s. 136. 
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