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Incisura terminalis

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incisura terminalis ear anatomy endaural incision

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Incisura Terminalis

The incisura terminalis (also called the terminal notch or intertragic notch) is a cartilage-free gap on the lateral ear, located between the superior aspect of the tragus and the root of the helix. It represents the natural cleft where the auricular cartilage is absent, making it an anatomically soft tissue-only zone.

Anatomy

  • Positioned at the superolateral entrance to the external auditory canal
  • Bounded superiorly by the root of the helix and inferiorly/anteriorly by the superior border of the tragus
  • Because it lacks cartilage, it is a relatively avascular, pliable area of the auricle
  • It corresponds to the region at the bony-cartilaginous junction of the ear canal at the 12 o'clock position

Surgical Significance — The Endaural Incision

The incisura terminalis is the key landmark for the endaural approach in otologic surgery (tympanoplasty, mastoidectomy, ossiculoplasty):
  1. The vertical limb of the endaural incision starts at 12 o'clock at the bony-cartilaginous junction and is directed laterally and superiorly into the incisura terminalis.
  2. Because the incisura is cartilage-free, the incision passes through soft tissue only — avoiding the need to cut auricular cartilage — which minimizes trauma and improves healing.
  3. Once placed, the incision can be deepened to expose the inferior edge of the temporalis muscle, where a fascial graft (temporalis fascia) can be harvested for tympanoplasty.
  4. The vertical limb can be extended medially and combined with horizontal canal incisions to form:
    • An inferiorly based skin flap in the bony canal
    • A laterally based Koerner (Koeber) flap extending onto the concha for meatoplasty

Additional Uses of the Region

The incisura terminalis is also used as the access point for tragal cartilage/perichondrium harvest — an incision on the medial aspect of the tragus, between the incisura terminalis and the tragal notch, allows composite graft harvesting for middle ear reconstruction. The image above shows this approach intraoperatively.
— Cummings Otolaryngology Head and Neck Surgery, Chapter 142 (Approaches and Incisions), p. 2729
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