A REVISED DESCRIPTION 
OF THE 
Anatomy of the Elephant’s Ear, 
BY 
ALBERT H. BUCK, M, D„ 
New York, 
Clinical Professor of the Diseases of the Ear, College of Physicians 
and Surgeons; Consulting Aural Surgeon, New York 
Eye and Ear Infirmary. 
[Reprinted from the Transactions of the American Otological 
Society, 1890.1 s 
MERCURY PUBLISHING COMPANY, PRINTERS, 
NEW BEDFORD, MASS. 
1890. A REVISED DESCRIPTION 
OF THE 
Anatomy of the Elephant’s Ear, 
BY 
ALBERT H. BUCK, M D„ 
New York, 
Clinical Professor of the Diseases of the Ear, College of Physicians 
and Surgeons; Consulting Aural Surgeon, New York 
Eye and Ear Infirmary. 
[Reprinted from the Transactions of the American Otological 
Society, 1890.] 
MERCURY PUBLISHING COMPANY, PRINTERS, 
NEW BEDFORD, MASS. 
1890, A REVISED DESCRIPTION OF THE ANATOMY 
OF THE ELEPHANT’S EAR. 
Albert H. Buck, M. D., New Toi-k, N. T. 
The discovery made by Dr. Richards, that the plane of 
section, which I had taken to be a horizontal plane, was 
in reality vertical, renders a large part of the description 
which I published in the Transactions of 1888 inaccurate. 
The restrictions under which I was placed by Prof. Wilder, 
who desired to preserve the specimen in as perfect a con- 
dition as possible for the Cornell Museum of Anatomy, 
rendered it an easy matter to be misled in regard to tbe 
true relations of these different sawed surfaces, to a vertical 
antero-posteriOr and a vertical transverse plane, and this 
must serve as my apology for the error which I was so 
unfortunate as to make. Thanks to the removal of these 
restrictions at a later date by Prof. Wilder, colleague 
has been enabled to study the specimen more thoroughly 
than I could, and he has determined accurately the rela- 
tions of these different parts. With the Society’s permis- 
sion, therefore, I submit herewith, for publication in this 
year’s volume of the Transactions, a corrected version of 
the account which was printed year before last. 
The specimen had been sawed out from the skull in 
such a manner as to show four plane and two uneven sur- 
faces. The plane surfaces are : a vertical one, which is 
situated just in front of the external auditory canal and mid- 
dle ear, leaving both of them intact, but traversing many 4 
BUCK 
of the large air cells which surround these parts; an in- 
ferior transverse section, which bisects the lower end of 
the middle ear a short distance below the point where it 
merges into the Eustachian tube ; a superior horizontal sec- 
tion which passes through an intercommunicating system of 
air cells ; and, finally, a median vertical section which leaves 
one condyle of the occipital part of the occipito-vertebral 
articulation attached to the specimen. The outer and pos- 
terior face of the specimen represents the natural surface 
of the skull as it appears after the soft parts have been to 
a great extent removed. The second specimen contains 
the entire Eustachian tube of the right side, trom its 
pharyngeal orifice to its termination in the narrowed lower 
end of the middle ear. The third specimen consists of the 
membranous portion of the 'left Eustachian tube, divided 
transversely at a point about five inches from its pharyngeal 
orifice, and slit up longitudinally throughout a large part 
of its length. All the specimens are preserved in alcohol. 
The external auditory canal.—The auricle had been cut 
away as close to the skull as possible, and all that remains 
of the cartilaginous portion of the canal is represented by 
two overlapping, funnel-shaped gutters of cartilage, which 
together form a complete conical framework around the 
skin-lined orifice of the external auditory canal. This ori- 
fice, which is nearly circular in shape, measures 9 millime- 
ters in diameter. It enters the skull in a direction nearly 
parallel with the plane of the transverse vertical section. 
At a distance of about 2 centimeters from the orifice, the 
canal begins to bend backward in its course, and at the 
same time its calibre becomes considerably larger. At a 
distance of 7 centimeters from the external orifice it measures 
15 millimeters in diameter. In the vicinity of the mem- 
brana tympani the calibre of the canal again diminishes in 
size, —to 9 or 10 millimeters, as nearly as I could ascer- 
tain. The ring of cartilage, representing, so to speak, the ANATOMY OF THE ELEPHANT’S EAR. 
5 
insertion of the auricle, loses itself in the cutaneous lining 
of the canal at a distance of about centimeters from the 
outer orifice.1 The entire length of the canal from the 
external orifice to the membrana tympani, measures 161- 
centimeters, or about inches. The skin lining the canal, 
Fig. 1. Vertical transverse section of the skull, a little in front of the external 
auditory canal. To expose the latter throughout the greater part of its course, the 
anterior wall of the bony cylinder has been chiseled away. (Reduced to one- 
third of the natural size of the parts.) 
lln this particular specimen the canal was found to be filled through- 
out its entire length with a semi-solid material which looked like an 
admixture of cerumen and cast-off epidermis scales. The natural infer- 
ence was, that the sedentary life and the unwholesome diet (candies, 
peanuts, etc.) to which show elephants are almost necessarily subjected, 
had produced this condition of what, in a human being, would be termed 
eczema. 6 
BUCK 
for a distance of about 2 centimeters (| inch) from the 
orifice, presents a finely corrugated appearance, the folds 
running in a direction parallel with the long axis of the 
canal. From this point inward, as far as to the drum-mem- 
brane, it presents a smooth, almost polished appearance. 
As may be seen in the figure, which represents the parts 
reduced to one-third of their natural size, the cylinder of 
bone constituting the external auditory canal lies in the 
midst of a labyrinth of intercommunicating cells or cham- 
bers of varying size and shape. About midway between 
the drum-membrane and the outer orifice this bony cylinder 
lies below a cavity of unusual size. How far this cavity 
extends upward I am unable to determine, as the upper 
part of the skull is not before me ; but that part of the 
cavity which is visible in the specimen measures a little 
over 11 centimeters (4| inches) in its transverse, and at 
least 15 centimeters (6 inches) in its vertical diameter ; this 
latter measurement extending from the surface of the section 
(superior transverse horizontal section) to the lower limits 
of that portion of the cavity which lies below and in front 
of the bony cylinder. x\ll these (presumably) air cham- 
bers communicate freely with each other, sometimes by 
very broad openings. So far as lam able to find out by 
careful exploration with a probe and by forcing smoke 
through different channels, these cavities do not communi- 
cate with the tympanum proper, but do apparently com- 
municate directly with the nasal system of cavities. In 
the human being the pneumatic cells do not communicate 
with the cavities belonging to the nasal system except 
through the Eustachian tube. In this respect, therefore, 
the mastoid cells' of the elephant differ materially from 
those of man. 
lln the human being pneumatic cells are found not only in the mastoid 
process, but also above the dense cylinder of bone which immediately sur- 
rounds the calibre of the external auditorj' canal,—that is, in the very same 
locality as that occupied by the cells here under consideration. Hyrtl, in ANATOMY OK THE ELEPHANT’S EAR. 
7 
v The Eustachian tube, from its pharyngeal1 or nasal ori- 
fice to the point where it emerges into the tympanic sys- 
tem of cavities, measures 11 centimeters (4| inches). Its 
nasal orifice, in the present specimen, is more or less muti- 
lated ; but it is evident that in its general features and size 
it resembles very closely the pharyngeal end of the human 
Eustachian tube. The latter is perhaps a trifle larger, and 
it stands out more prominently from the surrounding surface 
of the mucous membrane. Toward the tympanum the 
tube ends in a nicely rounded orifice, one side of which 
apparently corresponds with the termination of the long 
and thick cartilaginous cylinder, around which the tube is 
curved, gutter-like. As the specimen had been preserved 
in alcohol for two or three months I was not able to make 
out satisfactorily, by simple naked-eye inspection, the exact 
relations of the different tissues of the tube to each other. 
At the two orifices the calibre appeared to be small, i. e., 
simply large enough to admit easily a large-sized probe. 
A section near the middle portion of the tube revealed at 
first no calibre whatever, the opposite walls being appar- 
ently in perfect contact at all points. By manipulating 
the specimen, however, these closely applied walls could 
be made to separate, thus revealing to view a calibre large 
enough to admit the little and perhaps even the third finger. 
The top part of a question mark represents fairly well the 
cr<sss section of the calibre of the tube, when in a state of 
rest, at a point about half-way between the two orifices. 
Toward the tympanum the tube does not open directly into 
his “Anatomische Untersuchungen liber das Gehororgan des Menschen 
und der Saugethiere” (Prag, 1845), saJs that “the pars mastoidea of the 
temporal bone is, according to Kostlin, wanting in the hippopotamus, the 
elephant, and the rhinoceros.” 
xThe specimen is too fragmentary in character to warrant me in drawing 
any conclusion whatever in regard to the relations of the peripheral end 
of the Eustachian tube to the nasal and pharyngeal cavities. It is for this 
reason that I employ the terms pharyngeal and nasal indifferently. 8 
BUCK 
the tympanic cavity proper, but into an elongated air cham- 
ber, which lies anteriorly to this cavity, and opens into it 
through an elongated slit-shaped opening. This chamber 
commences as a cul-de-sac at the orifice of the tube, and 
gradually increases in size, throughout a length of between 
4 and 5 centimeters (about 2 inches). Like all the air 
chambers thus far mentioned, its walls consist of thin bone 
lined with a smooth mucous membrane. The antero- 
posterior diameter of the cavity, at a distance of centi- 
meters from the orifice of the tube, measures nearly three 
centimeters inches) ; the breadth varies but does not ex- 
ceed 1|- centimeters (| inch) at any part. The opening 
from this chamber into the tympanum proper is an elonga- 
ted slit and presents one or two peculiarities. The edge 
of the opening, on the side toward the median line, is pro- 
vided with two odd-looking osteophytes, one resembling 
a cock’s comb, the other a padded drum-stick, such as is 
used in beating a big bass drum. The slender handle 
of this miniature drum-stick is perhaps 4 millimeters long 
and scarcely half a millimeter thick, and at the end of it 
is a well rounded knob, fully two millimeters in length and 
about a millimeter and a half in thickness.1 
yrtl says nothing about the occurrence of these osteophytes in the 
elephant in particular, but he refers to their existence in some animals in 
the following words: “In certain animals possessing a roomy tympanic 
cavity there are found, either in the middle ear proper or in some of the 
cavities which communicate with it, bony outgrowths of characteristic 
shape. As these objects are found, with rare exceptions, to be always of 
about the same size and to occupy relatively the same positions, the infer- 
ence is permissible that they are not mere accidental formations, but prob- 
ably possess some functional importance. ******* In the 
posterior segment of the bulla [tympanica] of the lion these curious 
structures attain their highest degree of development, and may be seen 
here in the form of pear and othei' shaped bodies springing by a slender 
(sometimes hairlike) stem from the floor of this cavity.” From this 
description, and also from the pictorial representations which he gives of 
these bodies, it is clear that they are identical with those which I have 
described above. ANATOMY OF THE ELEPHANT’S EAR. 
9 
Still another peculiarity is observable at the opening 
which leads from the Eustachian vestibule, if I may so call 
it, into the tympanum proper. A little behind the opening 
the back wall of the vestibule becomes sharply grooved 
very much like the groove of bone which, in the human 
being, holds the belly of the tensor tympani muscle and 
runs upward, and finally a little forward to the anterior and 
middle portion of what may properly be termed the annulus 
Fig. 2. View of themembrana tympani and grooved ante- 
ro-external wall of the passage leading from the tym- 
panum proper to the Eustachian tube. The sharp-edged 
ridge running along the middle of the grooved antero- 
external wall and dividing it into two subordinate 
shallow grooves, may be seen in the picture. (About 
one-third natural size.) 
tympanicus. This groove extends so far outward that its 
outer wall is well outside of the plane of the drum-mem- 
brane. The anterior wall of the vestibule constituting 
one of the two grooves already mentioned displays three 
openings two oval in shape and one nearly circular 
which lead into adjacent air chambers ; the other groove 
is smooth and free from openings throughout its entire 
length. The chambers just mentioned have no communi- 
cation one with another, nor with any of the neighboring 
cavities. The antero-posterior diameter of the vestibule is 
21 millimeters (nearly | inch). The breadth of the pos- 
terior wall, opposite the osteophytes, is 1 centimeter (| 
inch). 
The tym-panic cavity.— Looked at from below, this 
cavity seems to be separated into two parts by a pro- 
jecting mass of bone, the sides of which form, roughly, an 
angle of 45°. That part of the cavity which lies nearer 
the median line is considerably larger than that which is 
in the immediate neighborhood of the drum-membrane. 
The roof of this outer cavity (or tympanum proper) pos- BUCK 
sesses certain peculiarities which will be described more 
fully by Dr. Richards. 
The antero-posterior diameter of the tympanic cavity, 
directly abreast of the membrana tympani, is 27 millime- 
ters inches) and its average breadth 25 millimeters 
(about 1 inch). Its height could not be accurately ascer- 
tained, but it must have been at least 50 millimeters (2 
inches). 
The outer wall is made up of the grooved structures 
which I have described above, and of the memhrana tym- 
■pani. This latter membrane, which is shown fairly well 
in Figs. 2 and 4, is decidedly conical in shape, as seen from 
Fig. 3. View of the tympanic cavity from within, showing (distinctly in the photo- 
graph but very faintly in the engraving) the stall-like openings behind and below 
the door of the tympanum, a part of the jagged wall surrounding the mouth 
of the well-like excavation, the two osteophytes and the grooved outer wall of 
the passageway leading from the tympanum to the Eustachian tube. (Slightly 
reduced in size.)1 
the side of the tympanum, while the surface of the mem- 
brane on the side toward the external auditory canal pre- 
sents scarcely any hollowing-out at all,—barely enough to 
lThe difficulties encountered in photographing the middle ear from 
different points of view were found to be very great, and as a consequence 
the half-tone pictures which accompany this article leave very much to be 
desired in the way of clear definition. ANATOMY OF THE ELEPHANT’S EAR. 
11 
justify the use of the expression, a shallow cone. This 
lack of agreement between the two surfaces is due appar- 
ently to two facts : the marked curving inward of the tip 
end of the manubrium mallei, and the great thickness of 
the soft parts in the vicinity of the umbo of the membrane. 
From the great resistance which the latter offers to pressure 
made at any point of its surface I should infer that its 
thickness is at no point less than one millimeter. As a 
whole the membrane is nearly circular in shape and meas- 
ures fully two centimeters (| inch) in diameter. 
Superiorly the tympanic cavity terminates in a cul-de-sac 
composed of soft tissues, which form a thick diaphragm 
separating the tympanum proper from a second, much 
smaller cavity containing the head of the hammer, all of 
the anvil, and presumably the stirrup. From the posterior 
part of this cul-de-sac the chorda tympani nerve passes for- 
ward, and then outward, in the form of a strong rounded 
cord, across the inner aspect of the neck of the hammer, 
at right angles to the manubrium. There is apparently no 
trace whatever of a tensor tympani muscle. 
The comparatively small area of bone surface constituting 
the inner wall of the tympanic cavity proper presents, di- 
rectly opposite the umbo of the drum-membrane, a rounded 
eminence in which no openings are visible. This is proba- 
bly the analogue of the promontory in the human being. 
Behind it, and situated at a higher level, is a rounded ridge 
of bone which terminates in a hooded opening or niche, 
suggesting the niche for the fenestra rotunda ; but a careful 
exploration with the probe fails to detect any break in the 
hard, bony surface at the bottom of the niche.1 Further- 
IHjrtl (op. cit.) says that the fenestra rotunda, in the elephant, is to be 
found behind an angular overhanging projection of the promontory, and 
that the actual opening of communication between the tympanum and 
the scala tympani is a mere narrow slit. He quotes Cuvier as saying that 
the fenestra rotunda of the elephant is very small, irregular in shape, and 
concealed behind a projecting part of the promontory. At the same time 12 
BUCK 
more, this niche faces forward and inward, whereas that 
of the fenestra rotunda in the human being faces backward 
cD 
and outward, and its position is altogether too far removed 
from the stirrup. The mere use of a probe is not sufficient 
to determine this question satisfactorily and I must, there- 
fore, leave it unsettled. The rest of the inner wall of the 
tympanum, down to the point where it bends abruptly 
around the blunt anterior edge of the promontory described 
above, presents no features of special interest. 
The posterior wall of the tympanum, in the vicinity of 
the promontory, is smooth, but on a line with the posterior 
margin of the annulus tympanicus it terminates abruptly 
in a thick, rounded edge which projects free into the air 
space. This edge represents the inner and lower termina- 
tion of the bony cylinder constituting the external auditory 
canal. In the excavation behind and beneath the edge 
of bone just mentioned may be seen three sharp-edged 
membranous septa, dividing the space into three deeply- 
shaded. r.ecesses and one shallow cul-de-sac, all facing 
obliquely inward. Taking them in regular order from 
above downward I explored each stall with the probe, and 
found that the first one is a mere cul-de-sac, extending to 
only a slight depth. The second one, which presents the 
largest opening, measures 33 millimeters (1| inches) in 
length and runs apparently directly behind, and nearly in 
the same direction with, the external auditory canal. By 
withdrawing the probe a short distance and at the same 
time causing it to press against the antero-inferior wall of 
the channel, one becomes conscious that the end of the 
instrument reaches the free edge of an elastic septum that 
divides this second stall into two subordinate channels. The 
long axis of this second subordinate channel measures 30 
millimeters (1| inches). The third stall is somewhat nar- 
he states that Kick (Ue.ber das Labyrinth des Elephanten, in Mueller’s 
Archiv, 1844, p. 431) believes that this opening' is the outlet of the aquae- 
ductus cochleae, and that the elephant has no true fenestra rotunda. ANATOMY OF THE ELEPHANT’S EAR. 
13 
rower at the entrance than the one just described. It 
consists apparently of a single passage without any bifur- 
cations, and measures, from the entrance to its farther end, 
nearly 70 millimeters (3| inches). Its general direction 
corresponds quite accurately with that of the external audi- 
tory canal. The fourth stall has a length of 53 millimeters 
(3 inches), and its long axis, whose general direction is 
outward, forms an angle of about 40° with the axis of the 
external auditory canal. The floor is lacking close to the 
entrance, and the space is occupied by a deep excavation 
from which the probe passes downward into a large cham- 
ber. 
The pit into which the stalls open is characterized by 
the presence, on its inner side, of a honey-comb structure 
which projects to such a degree as to partially conceal the 
entrances to the stalls. One of them is particularly con- 
spicuous by reason of its perfectly cylindrical shape, by the 
jagged character of its free edge, and by the depth (30 
millimeters—| inch) of the enclosed well, which seems to 
have no communication with any of the adjacent cavities. 
The large cavity which I mentioned in the earlier part 
of this description as forming an acute angle with the 
tympanum proper, presents few features of special interest. 
Its total length, or rather height, is approximately 50 milli- 
meters (3 inches) ; its maximum transverse diameter is 30 
millimeters inches) and the minimum 30 millimeters ( | 
inch). At the upper and back part of this subsidiary tym- 
panic cavity are two triangular openings with smoothly 
rounded edges. The inferior opening seems to lead into 
the general system of air cells which surround the exter- 
nal auditory canal; the superior opening leads into a long 
cavity, or system of cavities, which certainly do not com- 
municate with these cells. A probe introduced into this 
superior opening can be passed, in an outward and some- 
what upward direction, to a distance of 85 millimeters BUCK 
(3-| inches) without encountering any resistance. Several 
other openings are visible along the outer wall of the sub- 
sidiary tympanic cavity, but with one exception they all 
lead into shallow pockets or diverticula. In this single 
exceptional instance a slightly curved probe can be passed 
in to a depth of 25 millimeters (1 inch). This small curv- 
ing cavity is situated in the mass of bone which forms the 
Fig. 4. View of the subsidiary tympanic cavity as seen from within and behind, 
after the removal of the greater part of the anterior and upper boundaries. (Nat- 
ural size.) 
angle between the tympanum proper and the larger sub- 
sidiary cavity. 
We come, finally, to the consideration of the small cavity 
lying above and behind the tympanum proper, the cavity 
containing the anvil, the body or head of the hammer, and 
presumably the stirrup. The plate of bone covering both 
this cavity and that of the tympanum proper was found to ANATOMY OF THE ELEPHANT’S EAR. 
15 
be of considerable thickness, probably at least 5 millime- 
ters (T3g inch) thick. This smaller cavity, as we have 
mentioned before, is entirely shut off from the tympanum 
proper. It is, roughly measured, about ten millimeters 
inch) square. From the forward and outer corner of this 
cavity a probe can be passed, in a direction parallel with 
the long axis of the external auditory canal, a distance 
of 55 millimeters (2| inches) before it encounters any 
obstacle. By the smoke test it appears that this cavity or 
channel is a closed sac, having no communication with the 
adjacent system of pneumatic cells, and therefore not rep- 
resenting, in a physiological sense, the analogue of the 
mastoid antrum in the human being. 
The space between the tegmen tympani and the head of 
the hammer and body of the anvil, was found to be filled 
with a mass of soft connective tissue (almost like adipose 
tissue). Its removal disclosed to view the interlocking 
malleo-incudal joint. The body of the anvil overtowers 
the head of the hammer; that is, it is decidedl}’ nearer 
the tegmen tympani. There is quite free play between 
the two ossicles, both of which, however, may be de- 
scribed as being very solidly anchored in their respective 
positions. Considerable force may be applied to the handle 
of the hammer near the the membrana tympani 
before any visible excursion of the head of this ossicle can 
be distinguished. The same degree of force applied to the 
handle of the hammer apparently fails to produce any 
motion whatever in the anvil. Direct pressure upon the 
latter must be of a very decided character before visible 
motion can be excited in it. A strong membranous cap- 
sule spans the space between the opposite edges of the 
malleo-incudal joint.