pinna
Summary
The pinna (auricle) is the visible, cartilage-based flap of the outer ear. It collects sound waves and funnels them into the ear canal toward the eardrum, and its folds help the brain judge a sound's elevation and whether it is in front or behind. It does not transduce sound.
Detail
Meaning: The pinna (auricle) is the visible, cartilage-based part of the outer ear. It is the first structure on the path of sound: pinna → auditory canal → tympanic membrane → ossicles (malleus, incus, stapes) → oval window → cochlea. Its shape gathers sound waves and directs them inward. Its folds also alter the sound a little depending on the direction it comes from, giving the brain cues about elevation and front versus back.
On the MCAT: Expect a sequencing question on the path of sound, or a task of sorting structures into outer, middle, and inner ear. Localization questions pair the pinna with binaural cues: differences in arrival time and loudness between the two ears signal left versus right, while pinna filtering helps with up/down and front/back. A passage might ask what happens to localization if the pinna is covered or reshaped.
Common confusion: The pinna does not detect sound, and it is not the eardrum. It only collects and filters sound. Transduction into neural signals happens in the cochlea, where hair cells on the basilar membrane bend. The pinna belongs to the outer ear, while the ossicles belong to the middle ear.
Sources
- Psychology (Myers)
- Sensation and Perception (Goldstein)
Written for the MCAT and checked before it was published. For study reference only. Spotted an error? Let us know.