Presentation
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Patient Data
The intrinsic muscles are those that originate and insert within the external ear, while extrinsic muscles are those that originate elsewhere and insert onto the surfaces of the ear.
Case Discussion
The intrinsic muscles play a role in positioning and formation of the folds we can feel on our ears. The extrinsic muscles (auricularis superior, anterior and posterior) position the ear in place. These muscles are classified as vestigial, meaning through evolution we have lost their function, but the structure has been retained (although rare, some people can still move their ear via voluntarily contraction of these muscles).
The literature suggests that the auricularis anterior muscle is the most frequently missing, while agenesis of the auricularis superior and posterior have been associated with hypermobility of the ear (assessed by conchomastoid distance - the flat part of the external auditory canal to the mastoid process).
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