pinna (anatomy)

Last reviewed 01/2018

• Auricula or Pinna is of an ovoid form, with its larger end directed upward.
  • lateral surface is irregularly concave, directed slightly forward, and presents numerous eminences and depressions to which names have been assigned
  • prominent rim of the auricula is called the helix; where the helix turns downward behind, a small tubercle, the auricular tubercle of Darwin, is frequently seen
  • another curved prominence, parallel with and in front of the helix, is called the antihelix
    • this divides above into two crura, between which is a triangular depression, the fossa triangularis
  • narrow-curved depression between the helix and the antihelix is called the scapha
    • the antihelix describes a curve around a deep, capacious cavity, the concha, which is partially divided into two parts by the crus or commencement of the helix
      • the upper part is termed the cymba conchæ
      • the lower part the cavum conchæ
    • in front of the concha, and projecting backward over the meatus, is a small pointed eminence, the tragus, so called from its being generally covered on its under surface with a tuft of hair, resembling a goat's beard.
    • opposite the tragus, and separated from it by the intertragic notch, is a small tubercle, the antitragus
    • below this is the lobule, composed of tough areolar and adipose tissues, and wanting the firmness and elasticity of the rest of the auricula
  • cranial surface of the auricula presents elevations which correspond to the depressions on its lateral surface and after which they are named, e. g., eminentia conchæ, eminentia triangularis, etc.