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Chapter: Human Nervous System and Sensory Organs - The Ear

Outer Ear - Structure of The Ear

Outer Ear - Structure of The Ear
The auricle, or pinna (A, D1), with the ex-ception of the lobule, contains a scaffold of elastic cartilage.

Outer Ear

The auricle, or pinna (A, D1), with the ex-ception of the lobule, contains a scaffold of elastic cartilage. The shapes of the auricular projections and depressions are different in each person and are genetically determined. The shapes of the following parts are in-herited: helix (A11), antihelix (A12), scapha (A13), concha (A14), tragus (A15), antitragus (A16), and triangular fossa (A17). In the past, the features of the auricle were of special importance for establishing paternity.

The entrance of the outer ear canal, or ex-ternal acoustic meatus (D2), is formed by agroovelike continuation of the auricular car-tilage (D25) and is completed with connec-tive tissue to form a uniform passage. The passage is lined with epidermis, and large ceruminous glands lie beneath the epidermis.

 



The outer ear canal ends with the eardrum, or tympanic membrane (B, D18), which is obliquely placed in the meatus. When viewed from the outside, the mallearstria (B19) can be recognized; it is caused by the attachment of the manubrium of the mal-leus, which reaches to the umbo of the tym-panic membrane (B20), the innermost pointof the funnel-shaped eardrum. Above the upper end of the mallearstria (mallearprominence) lies a lax, thin part of the ear-drum, the reddish pars flaccida (B21), which is separated from the firm, gray and shiny pars tensa(B22) by two mallear folds. Theeardrum is covered externally by skin and internally by a mucosa. Between these lies the lamina propria of the pars tensa; it con-tains radial and nonradial fibers (C). The lat-terare circular, parabolic, and transversal. The fibrocartilaginous annulus (C23) forms the anchoring tissue of the eardrum.




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