Anatomy/Physiology of the ear Flashcards
What kind of epithelium does the external ear have?
Stratified keratinised epithelium
What causes cauliflower ear?
Bleeding between the cartilage and perichondrium which leads to scarring
What are the functions of the external ear?
To receive sound waves
What is the function of the middle ear?
Transmits sound waves from air to bone
Amplifies by bone to bone
Transmits sound to inner ear
What is the function of the inner ear?
Sound waves converted to nerve impulses (communicated to CNS by acoustic nerve CN VIII
Balance via vestibular organs
What are all the parts of the pinna?
Helix Triangular fossa Tragus Meatus Concha Antitragus Antihelix Lobule
Describe the histology of the external ear canal.
Lateral 1/3 - Skin with sebaceous glands in
subcutaneous layer (modified sweat
glands that produce wax)
Medial 2/3 - Skin and bone. No hair, no cilia, no wax
What makes the ear so prone to infection?
It is a warm, wet, dead end
How do you treat otitis externa?
Gentamycin
Ear drops
Not treated by most oral antibiotics
How do you orientate an image of the tympanic membrane?
Lateral process of the malleus points anteriorly so if it points right on the image, you are seeing the right ear.
What are some significant structures of the middle ear?
Ossicular chain
Facial Nerve (root of chorda tympani and nerve to stapedius muscle)
Eustacian tube opening
What are some associated structures of the middle ear?
ICA
IJV
Middle cranial fossa
Nasopharynx
What are the three components of the ossicular chain? (Ossicles)
Malleus (hammer)
Inus (anvil)
Stapes (stirrup)
(These all amplify sounds and can be disrupted by trauma or osteosclerosis)
What is the function of the eustacian tube?
Connects middle ear to nasopharynx and equalises pressure
What is one cause of acute OM?
Negative pressure can draw fluid into the middle ear, causing effusion
