Posterior auricular muscle

Structure

The posterior auricular muscle is found behind the auricle of the outer ear. It consists of two or three fleshy fasciculi. These arise from the mastoid part of the temporal bone by short aponeurotic fibers. They insert into the lower part of the cranial surface of the auricle of the outer ear.

The posterior auricular muscle is supplied by branches of the posterior auricular artery, which continues deep to the muscle. It is drained by the posterior auricular vein that accompanies the artery.

Nerve supply

The posterior auricular muscle is supplied by the posterior auricular nerve, a branch of the facial nerve (VII).

Function

The posterior auricular nerve draws the auricle of the outer ear backwards. This effect is usually very slight, although some people can wiggle their ears due to a more significant muscle movement. Electromyographic signals in humans suggest the posterior auricular muscle may be part of an ancient system for monitoring sounds we can't see.

Postauricular reflex

postauricular reflex

The postauricular reflex is a vestigial myogenic muscle response in humans that acts to pull the ear upward and backward. Research suggests neural circuits for auricle orienting have survived in a vestigial state for over 25 million years. It is often assumed the reflex is a vestigial Preyer reflex (also known as the pinna reflex).

A study on auriculomotor activity found that in the presence of sudden, surprising sounds, the muscles around the ear closest to the direction of the sound would respond by moving involuntarily, causing the pinna to be pulled backwards and flatten.

Clinical significance

If the posterior auricular muscle inserts into an unusual part of the auricle of the outer ear, this can cause protruding ears. In one study, the muscle was found to be absent in 5% of people.

References

References

1. (July 2015). "Abnormality of Auricular Muscles in Congenital Auricular Deformities". [[Plastic and Reconstructive Surgery]].
2. Niamtu, Joseph. (2018). "Cosmetic Facial Surgery". [[Elsevier]].
3. (2009). "Manual Therapy for the Cranial Nerves". [[Churchill Livingstone]] / [[Elsevier]].
4. (2025). "Electromyographic correlates of effortful listening in the vestigial auriculomotor system". Frontiers in Neuroscience.
5. Benning, Stephen D.. (2018-04-05). "The Postauricular Reflex as a Measure of Attention and Positive Emotion". Oxford Handbooks Online.
6. Benning, Stephen D.. (2011-03-01). "Postauricular and superior auricular reflex modulation during emotional pictures and sounds". Psychophysiology.
7. Hackley, Steven A.. (2015-10-01). "Evidence for a vestigial pinna-orienting system in humans". Psychophysiology.
8. "ZFIN Behavior Ontology: pinna reflex".
9. (2020-07-03). "Vestigial auriculomotor activity indicates the direction of auditory attention in humans". eLife.
10. Benning, Stephen D.. (2018-04-05). "Oxford Handbook Topics in Psychology". Oxford University Press.