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Auricularis posterior muscle

The auricularis posterior muscle is one of the three auricular muscles located around the external ear. It is the smallest of the group and is situated behind the auricle (external ear), playing a minor but distinct role in the movement of the ear. This thin, fan-shaped muscle is not well-developed in humans but contributes to subtle ear movements, particularly drawing the ear backward. Its importance is mostly anatomical, with relevance in head and neck surgery, imaging, and clinical neuroanatomy.

Synonyms

  • Musculus auricularis posterior

  • Posterior auricular muscle

Function

  • Retracts and elevates the auricle (external ear) slightly backward.

  • Assists in minor movements of the pinna, especially in response to sound localization in some individuals.

Nerve Supply

  • Supplied by the posterior auricular branch of the facial nerve (cranial nerve VII).

Artery Supply

  • Receives blood from the posterior auricular artery, a branch of the external carotid artery.

Vein Supply

  • Drained by the posterior auricular vein, which empties into the external jugular vein.

MRI Appearance

  • T1-weighted images: Appears as a thin, low-to-intermediate signal structure located posterior to the auricle, bordered by subcutaneous fat (high signal) and adjacent connective tissues.

  • T2-weighted images: Demonstrates a slightly higher signal than on T1, but remains lower than the surrounding fat and soft tissues.

  • STIR (Short Tau Inversion Recovery): The muscle appears with relatively low signal intensity, which can be differentiated from adjacent tissues with higher water content or inflammation (which would appear hyperintense).

CT Appearance

  • Visualized as a small, soft tissue density structure posterior to the auricle.

  • The muscle is less well-delineated than on MRI but can be identified by its location and relation to the external ear and mastoid process.

MRI images

Auricularis posterior muscle axial image

MRI images

Auricularis posterior muscle coronal image