ear

(ér) [L. au’ris; Gr. ods). The external car is composed of the awricle, or pinna, and the external auditory canal. The external curved border of the auricle is the helix, immediately in front of which is a hollow termed the fo a of the helix. In front of this fo a is the unthelix, a flattened, semicircular eminence on the cartilage of the external ear, situated before or within the helix, and immediately surrounding the concha posteriorly. Above the anthelix is a deep fo a, the fo a of the anthelix, which communicates with the concha, or large hollow of the auricle. Guarding the canal in front is a tentlike prominence, the /ragus. Opposite the tragus is the antitragus, a conic eminence of the lower posterior portion of the external ear, being part of the anthelix. The lower termjnation of the auricle is termed the /obule. The external auditory canal is about one inch and a fourth in depth, and is closed internally by the membrana tympani, or drum-membrane. The latter is composed of three layers --an outer or dermoid, a middle or Jibrous, and an internal or mucous, layer. The long proce , or handle, of the malleus is inserted in the inner surface. The middle car is the cavity on the inner side of the drum-membrane, containing the o icles; and communicating with the postnasal region by means of the eustachian tube. The internal car, or labyrinth, is embedded in the petrous portion of the temporal bone, and consists of three semicircular canals, communicating by means of the vestibule with the cochlea, resembling a minute spiral shell. Within the bony labyrinth is the membranous labyrinth, surrounded by the perilymph and containing endolymph. It is a closed sac, with the same form as the bony labyrinth. The cavity of the cochlea is divided by a partition, partly bony (/am’ina spira’lis) and partly membranous (membra'na basil a'ris), into the two spiral canals, the sca‘la restib’uli and the sca‘la tym’ pan i. The scala vestibuli is divided by the membrane of Rei ner into two portions, the lower of which. called the cochlear duct, contains the organ of Corti. This is made up of a series of rod-like bodies (Corti's rods, Corti’s fibers, or Gcoustic rods) arranged in a double row, attached by their bases to the basilar membrane, and united by their upper extremities to form the arches of Corti, which inclose a triangular space (Corti's canal or tunnel). In connection with the rods of Corti are several rows of cervical ciliated cells (Corti’s cells). Stretching above organ of Corti is a membranous structure called Corti’s membrane, or membrana tectoria. Aztec Θ., an ear in which the lobule is wanting, the whole ear looking as if it were pushed forward and downward. Blainville e's, asymmetry of the two ears. Cagot e., an ear in which the lobule is wanting. cat’s @., an ear that is folded over on itself. cauliflower e., a crumpled ear following the absorption of effusion after an injury. ᾽Β e@., an ear having an eminence on the edge of the helix. diabetic @., mastoiditis complicating diabetes. external @., the pinna and external meatus together. inner e., the labyrinth, comprising the vestibule, cochlea, semicircular canals, and the membranous canal. insane e., hematoma of the ear. middle e., the drum, or tympanum, comprising the aflic above, and the arium or lower space. Morel e., a deformed ear marked by abnormal development of the helix, anthelix, and scaphoid fo a, so that the folds of the ear seem obliterated, and the ear ts smooth, large, and often prominent, with a thin edge. Stahl e., No. 1, a deformed ear in which The organ of hearing. the helix is broad and coalesces with the anthelix; the fo a oval is and fo a scaphoidea are scarcely to be seen, and the lower portion of the helix is obliterated. Stahl e., No. 2, multiplication of the divisions of the crura furcata, so that there are three instead of two crura. Wildermuth’s 6., a deformed ear with prominent anthelix and poorly developed helix. earache (ér'ak). See ofalgia.