![]() ![]() The external acoustic meatus is a bony-cartilaginous, tubular component of the external ear. The former extends from the upper part of the eminentia scaphae to the eminentia conchae, while the latter bridges the inferior aspect of the same two structures. The obliquus auriculae and transversus auriculae muscles are found on the posterior (cranial) part of the external ear. Helicis minor travels obliquely along the crus of the helix, while helicis major courses over the anterior boundary of the helix after travelling vertically over its spine. Antitragicus originates from the anteroinferior part of the antitragus to the tail of the antihelix and helix. It is a flat, short muscle that is perpendicular to (but not in contact with) the antitragicus muscle. The tragicus muscle lies vertically on the lateral aspect of the tragus. The intrinsic group of muscles consists of the tragicus and antitragicus, obliquus auriculae, transversus auriculae and the helicis major and minor. There are two groups of muscles associated with the external ear. Finally, in the 6 o’clock position is the soft, fibrofatty structure called the lobule. The antihelix is separated from the helix by the scaphoid fossa (corresponding to the eminentia scaphae on the posterior aspect of the external ear). Apically, the antihelix has two crura surrounding a depression known as the triangular fossa. Another raised cartilaginous structure called the antihelix mirrors the path of the helix. ![]() The helix continues inferiorly and ends in the 4 o’clock position at the tail of the helix. The helix is the outermost concaved section of the ear and it has a small protuberance at the 2 o’clock position called the auricular tubercle. It starts at the concha of the auricle (depression at the orifice of the external auditory meatus that corresponds with the protruding eminentia conchae on the posterior surface of the ear) and extends anterosuperiorly in the 10 o’clock position (superior to the tragus) and continues as the prominent ridge known as the helix. Superior to the tragus in the 10 o’clock position is the crus of the helix. It is also a cartilaginous structure that is separated from the tragus by an intertragic notch. Posteroinferior to the tragus in the 5 o’clock position is the antitragus. As previously mentioned, it projects posteriorly from the 9 o’clock position to provide a lateral border to the distal end of the external acoustic meatus. On that note, the tragus is the first of several cartilaginous flaps in the ear. The left ear will be used as an example throughout, but keep in mind the mirroring necessary to discuss the right ear. However, the position of one structure, for example the tragus, will be in a 9 o’clock position on the left, but in a 3 o’clock position on the right. This is relevant because the different parts of the external ear can be related to a clock face. ![]() The skin, however, continues into the external acoustic meatus and covers the lateral surface of the tympanic membrane.īefore the different parts of the external ear can be discussed, it is important to note that the left and right ears are optical isomers of themselves (similar to the left and right hands). #Auditory canal skin#There is very little subcutaneous tissue between the auricular scaffold and the overlying skin of the ear. Finally, the mastoid process of the temporal bone lies posteroinferiorly with respect to the outer ear. Superior to it is the squamous part of the temporal bone, while the styloid process is located inferiorly. It is posterior to the zygomatic process of the temporal bone as well as the proximal part of the mandibular process and the auricular surface of the mandibular notch. The outer ear is situated superficially next to several bony landmarks. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |