Features of external auditory canal anatomy

Abstract

The external auditory canal is not only a part of the external ear, but also an integral part of the human auditory system, which conducts and amplifies the sound wave. In the field of otosurgery, it is often the priority access to the tympanic cavity, and therefore it is necessary to clearly understand the features of its anatomy. The dimensions and anatomy of the external auditory canal are extremely variable: the length is 2–3,5 cm, the diameter ranges from 5-9 mm, it is somewhat curved in the horizontal and frontal planes and consists of a membranous cartilaginous part and a bony part, between which there is the most the bottleneck – the isthmus. The ear canal is covered with skin, the thickness and structure of which depends on the section of the ear canal. The membranous cartilaginous section contains sebaceous and sulfur glands. Studies identify several forms of the bony part of the ear canal: conical, hourglass-shaped, ovoid, reverse conical, and cylindrical. The endoscopic scale (CES) for the visibility of the tympanic membrane was also proposed for the convenience of assessment. It has been suggested that the shape of the external auditory canal is an etiological factor in chronic otitis externa. Unambiguous interpretations of the relationship between ear diseases and the shape of the external auditory canal have not yet been obtained, but modern developments tend to consider its importance in the development of ear diseases. Clinical observations show that certain anatomical forms of it may be involved in the pathogenesis of chronic inflammation, since they interfere with proper self-cleaning.