Overview
This lecture covers the anatomical regions of the ear, defining the structures of the external, middle, and inner ear, and highlights their main components.
External Ear
- The external ear includes the helix, antihelix, tragus, antitragus, and lobule (earlobe) of the auricle.
- The ear canal is known as the external acoustic meatus.
- All structures up to the tympanic membrane (eardrum) are considered part of the external ear.
Middle Ear
- The middle ear begins at the medial side of the tympanic membrane.
- It contains the tympanic cavity and the auditory ossicles: malleus, incus, and stapes.
- The pharyngotympanic tube (Eustachian tube) connects the middle ear to the nasopharynx (back of the nasal cavity).
- The stapes rests on the oval window, a membrane that marks the boundary to the inner ear.
Inner Ear
- The inner ear starts at the medial side of the oval window.
- Main structures include the semicircular canals and the cochlea.
- Cranial nerve VIII, the vestibulocochlear nerve, is associated with the inner ear.
Key Terms & Definitions
- Helix — the outer rim of the external ear.
- Antihelix — curved prominence parallel to the helix.
- Tragus — small projection of cartilage in front of the ear canal.
- Antitragus — prominence opposite the tragus.
- Lobule (earlobe) — lower fleshy part of the auricle.
- External acoustic meatus — ear canal leading to the eardrum.
- Tympanic membrane — the eardrum, separates the external and middle ear.
- Auditory ossicles — three tiny bones (malleus, incus, stapes) in the middle ear.
- Pharyngotympanic tube (Eustachian tube) — tube connecting middle ear to nasopharynx.
- Oval window — membrane separating middle and inner ear.
- Semicircular canals — structures in the inner ear involved in balance.
- Cochlea — spiral-shaped organ in the inner ear responsible for hearing.
- Vestibulocochlear nerve (cranial nerve VIII) — transmits sound and balance information to the brain.
Action Items / Next Steps
- Review the anatomical diagrams of the ear regions and label each structure.
- Study the pathway of sound from the external ear to the cochlea.