Overview
This lecture covers the anatomy of the human ear, its main structures, and their functions in hearing and balance.
External Ear Anatomy
- The auricle (pinna) is the visible outer part of the ear.
- The external auditory canal is a tube that leads sound towards the tympanic membrane (eardrum).
Middle Ear Anatomy
- The tympanic membrane (eardrum) vibrates when hit by sound waves.
- There are three ossicles (ear bones): malleus (hammer), incus (anvil), and stapes (stirrup).
- Vibrations move from the tympanic membrane to the malleus, then to the incus, and finally to the stapes.
- The stapes transmits vibrations to the oval window, leading to the inner ear.
Inner Ear Anatomy & Function
- The cochlea is a spiral-shaped organ that processes sound.
- The vestibule contains the utricle and saccule, important for balance.
- Three semicircular canals, filled with fluid, help maintain dynamic equilibrium and sense motion.
- Spinning causes fluid movement in semicircular canals, leading to dizziness when stopped.
- The cochlear nerve carries sound information to the brain.
- The auditory (Eustachian) tube connects the middle ear to the back of the throat for pressure equalization.
Ear Structure Organization
- The ear is divided into three sections: outer ear, middle ear, and inner ear.
Key Terms & Definitions
- Auricle (Pinna) — the visible part of the outer ear.
- External Auditory Canal — tube carrying sound to the eardrum.
- Tympanic Membrane — the eardrum; vibrates with sound.
- Malleus — the "hammer" bone, first in the chain of ossicles.
- Incus — the "anvil" bone, second in the chain of ossicles.
- Stapes — the "stirrup" bone, last in the chain, sits on the oval window.
- Cochlea — organ in the inner ear for hearing.
- Vestibule — area of the inner ear for balance, contains utricle and saccule.
- Semicircular Canals — fluid-filled tubes for sensing motion and maintaining equilibrium.
- Cochlear Nerve — nerve carrying auditory signals to the brain.
- Auditory (Eustachian) Tube — connects middle ear to throat, equalizes pressure.
Action Items / Next Steps
- Review labeled diagrams of the ear and identify each structure.
- Study the functions of each part for better understanding of ear physiology.