The external ear consists of the expanded portion which is called the auricula or pinna, and the external acoustic meatus (ear cannel). The pinna projects from the side of the head and serves to collect the vibrations of the air by which sound is produced. The ear cannel leads inward from the bottom of the auricula and conducts the vibrations to the tympanic cavity.
The cartilage of the auricula consists of a single piece. It provides the form to the external ear. It is absent from the lobule. It is also deficient between the tragus and beginning of the helix, the gap being filled up by dense fibrous tissue. The posterior (cranial) aspect of the cartilage exhibits a transverse furrow, the sulcus antihelicis transversus, which corresponds with the inferior crus of the antihelix and separates the eminentia conchæ from the eminentia triangularis. The skin is thin, closely adherent to the cartilage, and covered with fine hairs furnished with sebaceous glands, which are most numerous in the concha and scaphoid fossa.
The relationships, dimensions, and proportions of the external ear have been thoroughly reviewed by Tolleth. At birth the ear is the same size in both sexes, but by the end of the first year boys' ears are larger than girls'. The full width of a boy's ear develops by age 13 and the full length by age 15. In girls, width is complete at age 10 and length at age 13. Ear width is approximately 55 percent of length. The long axis of the ear is tilted posteriorly from the vertical axis of the face at an angle ranging from 2-30 degrees. The axis of the ear and the nasal bridge, although similar, are not identical. The angle between them approximates 15 degrees, with the ear more vertical. The helical rim protrudes 1 to 2 cm from the skull, with the projection increasing from superior to inferior. In a normal ear, the rim is positioned 10 to 12 mm from the mastoid at the superior helix, 16 to 18 mm from the mastoid at midear, and 20 to 22 mm from the mastoid in the lower third. Although these measurements are most commonly used as a reference in setback otoplasty to avoid the classic
“telephone” deformity, they must also be carefully assessed and reproduced for an anatomically correct ear reconstruction in patients with microtia.
- Grey's Anatomy, The External Ear (both photos from this link)
- Core Curriculum Syllabus: Review of Anatomy - Temporal Bone and Ear--Baylor College of Medicine
- Basic Ear Anatomy--a Power Point Presentation
- Auricular Reconstruction for Microtia: Part I. Anatomy, Embryology, and Clinical Evaluation; Beahm, Elisabeth K. M.D.; Walton, Robert L. M.D.; Plastic & Reconstructive Surgery. 109(7):2473-2482, June 2002.
- Artistic anatomy, dimensions, and proportions of the external ear.; Tolleth, H; Clin. Plast. Surg. 5: 337, 1978.