Oblique Muscle of the Auricle
Ear · Head & Neck
The oblique muscle of the auricle is a small intrinsic muscle on the cranial (medial) surface of the external ear. It arises from the auricular cartilage over the upper part of the concha and passes obliquely to attach over the eminentia triangularis, the prominence above the concha. Like the other intrinsic ear muscles, it is vestigial in humans and serves only to modify the shape of the auricle rather than to produce any purposeful movement. It receives its motor supply from the facial nerve (CN VII) through the posterior auricular branch, in keeping with the facial nerve's control of all the muscles derived from the second pharyngeal arch in this region.
Origin, Insertion, Action & Nerve
Origin
Cranial (medial) surface of the auricle over the upper part of the concha
Insertion
Cranial surface over the eminentia triangularis (above the concha)
Action
Modifies the shape of the auricle (vestigial)
Nerve
Posterior auricular branch of facial nerve (CN VII)
Attachments explained
The Oblique Muscle of the Auricle is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Cranial (medial) surface of the auricle over the upper part of the concha
Insertion
Cranial surface over the eminentia triangularis (above the concha)
Action & function
When the Oblique Muscle of the Auricle contracts, it produces the following movement: Modifies the shape of the auricle (vestigial).
As part of the Ear group of the Head & Neck, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Oblique Muscle of the Auricle receives its nerve supply from the Posterior auricular branch of facial nerve (CN VII).
Because a muscle can only contract when its nerve is intact, injury to the Posterior auricular branch of facial nerve can weaken or paralyse the Oblique Muscle of the Auricle, impairing the movements it normally produces (modifies the shape of the auricle (vestigial)). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Oblique Muscle of the Auricle (the OIANS method)
Study the oblique auricular muscle alongside its transverse neighbour, since the two are easily confused. Distinguish them by their line of pull: the transverse muscle runs across from the conchal eminence to the scapha, whereas the oblique muscle runs obliquely from the upper concha to the eminence of the triangular fossa. Both sit on the hidden back surface of the cartilage, so both merely alter the shape of the auricle without useful effect.
Lock in the innervation by remembering that every intrinsic ear muscle shares the same motor nerve, the facial nerve (CN VII) via its posterior auricular branch. For exam purposes the useful facts are that this muscle is vestigial and that its supply is facial, not trigeminal. Treating the oblique and transverse auricular muscles as a matched pair with identical innervation and near-identical function reduces the memory load considerably.
Frequently asked questions
Where is the Oblique Muscle of the Auricle located?
The Oblique Muscle of the Auricle is a muscle of the Ear group, located in the Head & Neck.
What is the origin of the Oblique Muscle of the Auricle?
Cranial (medial) surface of the auricle over the upper part of the concha
What is the insertion of the Oblique Muscle of the Auricle?
Cranial surface over the eminentia triangularis (above the concha)
What movements does the Oblique Muscle of the Auricle produce?
Modifies the shape of the auricle (vestigial)
What nerve supplies the Oblique Muscle of the Auricle?
Posterior auricular branch of facial nerve (CN VII)
Is the Oblique Muscle of the Auricle free to study in OIANS?
The Oblique Muscle of the Auricle is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Head & Neck is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
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