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CHAPTER IV.

DISEASES OF THE AURICLE, MASTOID REGION, AND EXTERNAL

MEATUS.

Anatomy of the Auricular Region: the Auricle and External Auditory Canal.—Congenital Malformations and Diseases of the External Ear; Irregular or imperfect Development.-Wounds and Injuries of the Auricle.- Alterations in form.—Morbid Growths. Inflammations.-Gout.-Cutaneous Affections: Eczema, Herpes, and Pemphigus.— Cancer. Affections of Mastoid and Auricular Regions.-Post-aural Tumours.- Disease of Mastoid Gland.-Inflammation of Periosteum.-Chronic Abscess.-Aneurism. -Caries. Cerebral Otorrhœa.—Injuries of External Meatus: Foreign Bodies in.— Diseases of Cerumenous Glands.-Inflammations: Acute, Chronic, and Specific.-External Otorrhoea.-Fistula and Caries.-Cutaneous Diseases; Piligrowth.-Morbid Growths. Polypus, Exostosis.-Alterations in form of Canal.—Malignant Diseases.

IT

T is not my intention to enter minutely or at any length upon the subject of the anatomy of the organ of hearing, but simply, to preface the description of the diseases of each particular part with a brief sketch of the structures which those diseases engage, in order to revive in the memory of the reader some general knowledge of the parts under consideration.

An ear consists of two portions, a sensitive and a mechanical; the latter being generally subservient to the former, and modified according to the peculiar habits, exigencies, and mode of life of the different classes of animals: in fishes, cetacea, and amphibians, to inhabit the water; in birds and insects, to progress through the air; in moles, to burrow and seek their food under the ground; and in man and other terrestrial animals, to walk on the earth.

The human ears are situated in the temporal bones, one on each side of the cranium. Each temporal bone consists of three parts, the superior, thin, squamous, or scale-like portion, which overlaps the frontal and parietal bones upon the temporal region, but which is seldom engaged in aural diseases; the mastoid, or posterior inferior part, thick and rough for the attachment of muscles, and hollowed into cells, which communicate with the cavity of the tympanum, for the purpose of increasing the surface.

on which sound acts; and the petrous portion, so named from its stony hardness, which passes inwards from the junction of the two former to form a part of the lower arch or base of the skull; besides various processes, the chief of which are the zygomatic and the styloid. In the petrous portion is placed the special organ of hearing. Anatomists have divided the ear into thice parts: the internal, or labyrinth, containing the expansion of the auditory nerve, and including the cochlea, vestibule, and semicircular canals; the middle, or cavitas tympani, enclosing the chain of ossicles, bounded externally by the membrana tympani, and internally by the outer wall of the labyrinth, communicating posteriorly with the mastoid cells, and having an inferior exit through the Eustachian tube; and the external ear, consisting of the meatus auditorius externus, and the pinna or auricle.

Viewed externally, the parts which become concerned in diseases of the ear, and which may be styled the aural region, are contained within that space between the malar bone in front, and the edge of the occipital behind, bounded above by the attachment of the temporal muscle, and below by a line drawn from the angle of the jaw to the lower margin of the mastoid process. In the centre of this lateral space of the head is placed the auricle, a cartilaginous projection, varying in size, shape, and angle of attachment in different races of men, as well as in different individuals; and in the lower animals presenting all those modifications applicable to their respective circumstances and habits of life, with which every one is familiar. The human ear is an irregularly-curved plate, with its concavity directed forwards and outwards. It consists of the outer fold or hem turned over on itself, and called the helix, broad and deep in front, where it rises from the upper boundary of the external meatus, and gradually becoming narrow, thin, and fleshy, as it is lost in the lobe behind and below. Its size, shape, and amount of overlapping varies considerably in different individuals, and in many persons this fold is altogether wanting, particularly posteriorly; we also frequently find in it small hard nodules. Within the helix is another elevation, denominated the anti-helix, of a somewhat triangular shape, arising in front by two roots from behind the

anterior curvature of the helix. Curving upon itself, it forms the superior and posterior boundary of the concha, and ends in the anti-tragus, a nipple-like projection from which the lobe depends. Between the eminences of the helix and anti-helix runs a deep groove, called the navicular fossa; while the space between the roots of the anti-helix is-after the usual fashion of the old anatomists, when they had exhausted their various similitudes-called the fossa innominata. In front of the external auditory aperture, which it partially overlaps, and arising below the roots of the zygomatic process, is a concave triangular projection, called the tragus, on account of a tuft of hair resembling a goat's beard, which in some persons, particularly in advanced life, grows from its tip. From the base of the tragus being in immediate contiguity with the temporo-maxillary articulation, it is moved by the action of the jaw, particularly in eating. The cellular and adipose substance in front of its anterior edge is often the seat of inflammation, and hence arises the pain experienced in such cases from any motion of the lower jaw; and the temporal artery passing through this space, and there giving off the anterior auricular, may account for the unusual amount of throbbing felt in abscess of this region. The largest concavity is the concha, which, leading into the meatus in front, forms posteriorly the hollow of the external ear, and is bounded above by the roots of the helix and anti-helix, behind by the concave margin of the latter, and below by the anti-tragus and a gutter-like fossa, which passes downwards somewhat in front of the lobe. The concha is generally capacious enough to contain the top of the thumb. All these eminences and depressions, as well as the posterior, inferior, and a part of the anterior margin of the meatus, are fashioned out of one continuous cartilage, which may be denominated the skeleton of the car. Pendant from the lower edge of this cartilage is the lobe, a fleshy projection, more or less long and thick in different individuals, and passing off anteriorly into the integuments of the cheek beneath the tragus. It contains a quantity of cellular and some adipose tissue, and is very extensile, as may be seen in inflammations, dropsy, and emphysema, &c. From time immemorial, and among all nations, this part has been adorned.

The cartilaginous portion of the ear is invested with a strong perichondrium, and the whole is covered with an envelope of fine integument, highly vascular and sensitive, so as to be even susceptible of blushing and other peculiar impressions consequent upon mental emotion. It contains many sebaceous follicles, particularly in the concha, where they sometimes become enlarged, and present those dark worm-like bodies with which every one is familiar. In some adults the auricle has a thick, leathery feel, and it is often, even in the normal state, of a bluish purple colour. Even in some new-born children we observe hair growing from the upper margin of the helix, and in several hirsute males in middle life this is a common place for tufts of hair to project from, as well as from the anterior surface of the lobe, the tragus, and the anti-tragus. The hairs growing from these parts and around and within the external meatus, though short, are generally very stiff, like the eyebrows of some aged persons, and often become a source of annoyance either by being entangled with the cerumen, or by falling inwards, and irritating the membrana tympani.

The auricle is attached by ligaments, muscles, and the common integuments, to the skull, and by dense ligamento-cellular membrane to the anterior, inferior, and posterior margin of the meatus, extending from the root of the zygoma to the mastoid process. Among civilized nations this part is not so well developed, does not stand out at the same angle from the head, and its muscular apparatus is not so much called into action as in savage people, whose means of safety or subsistence depend to a certain extent on their powers of hearing. Any one who ob serves the ears of a greyhound when that animal's attention is specially engaged may form some idea of the beautiful muscular apparatus which an ear in its natural condition possesses. Still, we often meet persons who have the power of moving the external ear in different directions, principally upwards, backwards, and a little forwards.

Two sets of muscles have been described as belonging to the human ear, but in the great majority of individuals they are either rudimentary or are altogether wanting. The first, or the extrinsic, are those which, attached to the head, move the exter