Triangular Fossa: The concavity bounded by the superior and inferior crura of the antihelix and the ascending portion of the helix. The inferoposterior margin of the tragus forms the anterior wall of the incisura. Tragus: A posterior, slightly inferior, protrusion of skin-covered cartilage, anterior to the auditory meatus. Scapha: The groove between the helix and the antihelix. The earlobe is highly variable in size and in the degree of attachment of the anteroinferior portion to the face. It is bounded on its posterosuperior border by the end of the descending helix, on the anterosuperior border by the inferior border of the antitragus and superiorly by the incisura. Lobe: The soft, fleshy, inferior part of the pinna. The average crus helix extends about one half to two thirds the distance across the concha. Helix, Crus: The continuation of the anteroinferior ascending helix, which extends in a posteroinferior direction into the cavity of the concha above the external auditory meatus (Figure. Lange developed a graphic classification of folding variants. The border of the helix usually forms a rolled rim but the helix is highly variable in shape. The lower portion of the posterior part is often non-cartilaginous.
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The helix can be divided into three approximate parts: the ascending helix, which extends vertically from the root the superior helix, which begins at the top of the ascending portion, extends horizontally and curves posteriorly to the site of Darwin tubercle (vide infra) the descending helix (sometimes called posterior), which begins inferior to Darwin tubercle and extends to the superior border of the earlobe. Helix: The outer rim of the ear that extends from the superior insertion of the ear on the scalp (root) to the termination of the cartilage at the earlobe. The Frankfurt horizontal or Frankfurt plane is used as the general horizontal plane of the head and as reference point for other planes and structures. Frankfurt Horizontal: A plane connecting the lowest point on the lower margin of each orbit and highest point on the upper margin of the external auditory meatus ]. It is usually bisected by the crus helix into the cymba superiorly and cavum inferiorly. Concha: The fossa bounded by the tragus, incisura, antitragus, antihelix, inferior crus of the antihelix, and root of the helix, into which opens the external auditory canal.
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The anterosuperior margin of the antitragus forms the posterior wall of the incisura. Antitragus: The anterosuperior cartilaginous protrusion lying between the incisura and the origin of the antihelix. A synonym is the posterior crus of the antihelix. The superior crus runs in a superior and slightly anterior direction and is usually less sharply folded than the lower portion and inferior crus. Antihelix, Superior Crus: The upper cartilaginous ridge arising at the bifurcation of the antihelix that separates the scapha from the triangular fossa. A synonym is anterior crus of the antihelix.
The inferior antihelical crus runs in an anterior and slightly superior direction, is usually sharply defined, and appears less variable than its superior counterpart. Antihelix, Inferior Crus: The lower cartilaginous ridge arising at the bifurcation of the antihelix that ends beneath the fold of the ascending helix, and separates the concha from the triangular fossa. The inferior and superior crura of the antihelix can vary both in volume and degree of folding. The stem (the part below the bifurcation) of the normal antihelix is gently curved and branches about two thirds of the way along its course to form the broad fold of the superior (posterior) antihelical crus, and the more sharply folded inferior (anterior) crus. The antihelix represents a folding of the conchal cartilage and it usually has similar prominence to a well-developed helix. The anatomy of the various components of the ear are described below, and illustrations are shown each time in the section describing the various features of the components.Īntihelix: A Y-shaped curved cartilaginous ridge arising from the antitragus and separating the concha, triangular fossa, and scapha.
#Helix definition skin
The external ear consists of skin (with adnexa), cartilage, and six intrinsic muscles. The major landmarks of the external ear are depicted in Figure 1. The anatomy of the external ear, also known as the auricle or pinna, is complex ] and remarkably inaccurately described by most authors.
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