![]() 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 (Fig. 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 (Fig. Figure 30 illustrates some variation in the helix observed among a small group of colleagues. Lange 1966 developed a graphic classification of folding variants (Fig. 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. 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 (Fig. 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. 18).įrankfurt 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 (Fig. The anterosuperior margin of the antitragus forms the posterior wall of the incisura.Ĭoncha: 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. A synonym is the posterior crus of the antihelix.Īntitragus: The anterosuperior cartilaginous protrusion lying between the incisura and the origin of the antihelix (Fig. The superior crus runs in a superior and slightly anterior direction and is usually less sharply folded than the lower portion and inferior crus. A synonym is anterior crus of the antihelix.Īntihelix, superior crus: The upper cartilaginous ridge arising at the bifurcation of the antihelix that separates the scapha from the triangular fossa (Fig. The inferior antihelical crus runs in an anterior and slightly superior direction, is usually sharply defined, and appears less variable than its superior counterpart. ![]() The inferior and superior crura of the antihelix can vary both in volume and degree of folding.Īntihelix, 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 (Fig. 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. Antihelix: A Y-shaped curved cartilaginous ridge arising from the antitragus and separating the concha, triangular fossa, and scapha (Fig.
0 Comments
Leave a Reply. |