Test 4 Review Flashcards
What is the pinna?
Everything on the outside that attaches to your ear.
What is the external auditory canal?
Everything inside, starting from the little hole and going further back into the eardrum.
What is the pinna made out of?
The whole thing is made out of cartilage EXCEPT for the earlobe, which is made of fat and vascularization.
What is the function of the concha?
The concha helps with localization of sound in that in helps funnel the sound into the ear. The bulk of the sound increasing in collection id done in the concha.
What is the function of the helix and antihelix?
They help with pinna cues in timing and localization.
How many cranial nerves innervate the ear?
Five; Greater auricular, auriculotemporal, facial, auricular branch of vagus, and the lesser occipital
What does the greater auricular innervate?
Sensory innervation to parts of the outer ear [tragus, anterior wall, external auditory meatus]
What does the auriculotemporal innervate?
Parts of the outer ear (helix and antihelix)
What does the facial nerve innervate?
The stapedius muscle
What does the auricular branch of the vagus innervate?
The ear canal and tympanic membrane
What does the lesser occipital innervate?
Helix of ear
What artery supplies the pinna and ear canal and what are the branches?
The external carotid artery.
1. Superficial temporal artery: anterior portion of pinna, tragus, anterior helix, earlobe, and ear canal.
2. Posterior auricular artery: posterior portion of pinna and ear canal
3. Maxillary artery: Ear canal
What are the functions of the outer ear?
Captures sound
Acts like a pre-amplifier [sound boost]
Changes the timing of sounds
Helps locate objects
True or False: Different parts of the pinna add different amounts of gain to the total sound collected.
True
What is microtia?
A condition where the external ear is underdeveloped or malformed at birth.
What is anotia?
A completely undeveloped ear
What clinical signs would you expect to see with a person who has microtia/anotia?
Preauricular pit, peanut ear, complete absence of ear
How is microtia/anotia treated?
If the ear canal is there and the ear just closed up:
1. Drill out the entrance
2. Install a prosthetic
What is an auricular hematoma?
Swelling of fluid and pooling of blood.
Boxers’ ear [also called cauliflower ear]
Results from blunt force trauma. Vesicles open, ear floods with blood and fluids. If not treated, it hardens.
What is basal cell carcinoma?
Cancer that first shows as a red flaky spot on the antihelix. Scabs over: Open leaky sore. The longer it sits-more it will spread to the rest of the body.
Sunburning of the ear:
Overabundance of radiation that destroys outer skin cells. When this occurs frequently, it is the cause of starting the cancer cycle (with apoptosis).
What is perichondritis?
Bacterial infection for the cartilage/connective tissue. Results from trauma, punctures, piercings, and surgeries. Lose epidermal protective layering. Treated with strong antibiotics.
What is otitis externa?
Infection of the outer ear.
Red flakiness, tenderness, super oily ear, oozing earwax, also called swimmers’ ear. Treated with over the counter ear drops.
External auditory canal:
General S shape. No 2 ear canals are the same. 1/3 cartilage, intermedial 2/3 skin on bone. Osteocartilaginous junction: 1/3 cartilaginous, 2/3 bony
Lateral 1/3 of external auditory canal:
Passes through cartilage
Contains sebaceous glands, which secrete sebum for earwax production
Contains hair follicles
Earwax:
Combination of oil from the sebaceous glands and wax from the ceruminous glands. Mixing them together creates cerumen.
Biggest factor: Race but also very person specific. Slightly acidic (antifungal), serves as water repellent. Function: Lubricates, cleanses, and protects the ear.
What is excessive/impacted cerumen caused by?
Q-tips, Insert earphones, and earplugs
Can result in: Dizziness, hearing impairment, ringing in the ear, plugged sensation, soreness, and itching in the ear.
What is exostosis (osteoma)?
A benign growth of bone on top of existing bone (Surfer’s ear)
Can cause: Decreased hearing, more frequent earwax impaction, and discomfort in rare cases. Extreme cases: Drill out and reopen the ear canal
What is the tympanic membrane?
The eardrum; it marks the border between the outer and middle ears.
Concave shape
3 layers:
1. Outer layer-same as EAC
2. Middle Layer: Tough fibrous connective tissue
3. Inner layer: Mucous membane
What are the landmarks of the tympanic membrane?
Malleus: Largest bone of the middle ear
Umbo: Tip of malleus that terminates near the middle of TM
Annulus: Ring of tissue that holds the TM in position at the end of the EAC
Pars Tensa: Taut area of TM (largest position)
Pars Flaccida: Area of loose tissue above the malleus
Cone of light: Light reflections observed in the anterior-inferior quadrant (otoscopy)
What is the purpose of the tympanic membrane?
To connect sound from the outer to the middle ear
To protect and separate the outer ear from the middle ear.
What is a perforation?
When the tympanic membrane has a hole, tear, or break in it.
It can heal on its own over time, or be “patched” with a surgery
What is tympanosclerosis?
White scarring of the tympanic membrane caused by calcium phosphate deposits in the middle and interior layers of the tympanic membrane.
Can be caused by frequent otitis media or repeated perforations.
The Middle Ear:
Air Filled Space.
Transmits sound-induced mechanical vibrations to fluid-filled cochlea. Eardrum and ossicles are the interface through which airborne vibration is converted to fluid vibration. Encased int he temporal bone. Normally closed but opens during swallowing and yawning.
What comprises the ossicular chain?
Malleus, incus, stapes
What are the middle ear muscles?
Tensor tympani and stapedius muscle