Human Auricular Muscles: Vestigial or Functional?

The auricular (extrinsic ear) muscles—anterior, superior, and posterior—are not vestigial in the strict evolutionary sense (they are not functionless remnants). However, in humans they are highly atrophied and functionally negligible compared to many mammals.

Anatomy and Innervation

• Anterior auricular muscle: Pulls pinna forward/upward.
• Superior auricular muscle: Elevates pinna.
• Posterior auricular muscle: Pulls pinna backward.
• All innervated by the facial nerve (CN VII) (temporal and posterior auricular branches).

Comparative Perspective

In cats, dogs, horses, and many mammals, these muscles are robust, enabling precise pinna orientation for sound localization and threat detection. Humans have lost this mobility; the muscles are thin, variable, and produce only minimal, often imperceptible movements.

Current Human Function

• Residual mobility: Some individuals can voluntarily wiggle ears (genetic trait).
• Reflexive activity: Minor contractions to sudden sounds (vestigial orienting reflex).
• Surgical relevance: Postauricular muscle used as flap in otologic surgery; facial nerve monitoring during parotid/ear surgery.

Thus, while not "vestigial" in the sense of being completely absent or non-functional (they retain innervation and minimal contractility), they serve no meaningful auditory or communicative purpose in modern humans.