Ear Flashcards
What is the function of the ear?
Hearing & balance
What are the three components of the ear?
External, middle, and internal (neuro 2023)
What is the external ear comprised of?
Auricle (pinna) and external auditory meatus
What tissue is the external ear comprised of?
Elastic cartilage
What does the auricle do?
Assist in capturing sound -> numerous folds & depressions
How does the auricle go?
Funnels to external auditory meatus
What is cauliflower ear? How does it occur?
Hematoma within layers, which causes avascular necrosis and is fibrotic
Occurs primarily to fights due to repetitive blunt trauma
What is the blood supply of the external ear?
Superficial temporal artery, posterior auricular artery, deep auricular artery (from maxillary)
What is the venous drainage of the external ear?
Follows pattern of arteries
What is the lymph drainage of the external ear?
Parotid (anterior + external acoustic meatus), mastoid (posterior), and deep cervical nodes
What is the GSA innervation of the external ear?
Auriculotemporal nerve (CN V)
Lesser occipital nerve (C2, C3)
Great auricular nerve (C2, C3)
Auricular branch of CN X
CN VII
CN IX
What is the external auditory meatus?
Extends from the deepest part of concha to the tympanic membrane (~ 1 inch)
Lateral 1/3 is cartilaginous, medial 2/3 is bony (temporal bone)
Covered in skin -> contains hair follicles and ceruminous glands (ear wax)
What is the innervation of external auditory meatus?
- Auriculotemporal nerve
- CN X (auricular branch)
- CN VII
- CN IX
What is the purpose of the tympanic membrane?
Separates EAM from middle ear
Lateral surface angled anteroinferior (~55*)
How to use cone of light?
Allows you to see the side of the ear you are looking at
What is the connective tissue lined with?
Laterally -> connective tissue
Medially -> mucous membrane
The lateral surface of tympanic membrane innervation
3/4 auriculotemporal nerve, 1/4 CN X, some from CN VII
The medial surface of tympanic membrane innervation
CN IX (tympanic nerve)
What is impacted in Swimmer’s ear?
Auriculotemporal nerve, vagus nerve
Where would lymphadenopathy be for Swimmer’s ear?
Parotid gland
How is the middle ear separated from the external auditory meatus?
Tympanic membrane
Space within the temporal bone is lined with…
Mucous membrane
What is the function of the middle ear?
Transmit vibrations of tympanic membrane to inner ear via three ossicles -> malleus, incus, stapes
What are the boundaries of the middle ear?
Lateral -> tympanic membrane + temporal bone
Medial -> lateral wall of inner ear (promontory + tympanic plexus), prominences of lateral semicircular canal and facial canal
Anterior -> temporal bone adjacent to carotid canal
Posterior -> adjacent to mastoid air cells
What are the openings of the middle ear?
- Pharyngotympanic tube
- Aditus to mastoid antrum
- Oval and round windows
What can break through membrane of middle ear?
Infections
What opening communicates with pharyngotympanic tube?
Nasopharynx
What opening communicates with mastoid antrum?
Aditus to mastoid antrium
What are the ossicles?
Mallelus, incus, and stapes
How do the ossicles articulate?
True synovial joints
How is the malleus attached?
Tympanic membrane via handle
How is the stapes attached?
Oval window via base
What is otoscleosis?
Abnormal growth around bone ossicles, usually involving stapes -> causes productive hearing loss
What is the key finding of the mallelus?
Ice cream cone
What are the two muscles in the middle ear?
Stapedius (CN VII) and tensor tympani (CN V3)
Responsible for protection against loud noise
What is hyperacusis?
Increased senisitvity to sound -> caused by injury to CN VII
What nerves run through the middle ear?
Tympanic nerve (CN IX) and lesser petrosal nerve (CN IX)
What info does lesser petrosal nerve?
GVE + GVE
Where does chorda tympani course?
Medial to handle of mallelus
What information does the chorda tympani carry?
SVA, GVE, GVA
The pharyngotympanic tube is fixed…
Between greater wing of sphenoid and petrous part of temporal bone
What is the innervation of pharygotympanic tube?
Tympanic plexus (CN IX), pharyngeal branches from PPG
What is otitis media? Who is it common in?
Middle ear infection, in younger children
Nerves at risk: chorda tympani, tympanic nerve, internal carotid
How do you place tympanostomy?
Inferior aspect in order to avoid chorda tympani
What is mastoiditis?
Inflammation of mastoid due to recurrent middle ear infection
What is the lymphatic drainage of middle ear?
- (External Meatus [otitis externa, infected piercing] – parotid >
jugulodigastric > mastoid) - Middle Ear [otitis media] – parotid > jugulodigastric
- Pharyngotympanic Tube – retropharyngeal
What is the venous drainage of middle ear?
To transverse and superior petrosal sinuses, pterygoid venous plexus
What is the arterial supply of middle ear?
- Maxillary a.
- Posterior auricular/occipital aa.
- Middle meningeal a.
- Ascending pharyngeal a.
- Tympanic branch from internal carotid a.
