Nasal cavity, paranasal sinuses & ear Flashcards
What are the boundaries of the nasal cavity?
Nares to choanae
What are the nasal choanae?
Two oval openings at back of nasal cavity that take you into the nasopharynx
What type of epithelium is the nasal cavity lined with?
Respiratory type epithelium - pseudostratified ciliated
How many concha are there and what are the names?
3 - superior, middle & inferior
What is the meatus?
The area between the concha
What are the functions of the nasal cavity?
- Filter air - concha create turbulent air flow – air is forced against nasal mucosa (goblet cells produce mucus) – trap particulate matter
- Warm & moisten air – highly vascularised mucosa – air warms up as it spins against it
- Cavity & paranasal sinuses produce resonance in voice
- Receptor for sense of smell
What is CSF rhinorrhoea?
Trauma to the nose can fracture the cribriform plate in the ethmoid, damaging the dura + arachnoid, causing CSF to leak out the nose
What is the area called where multiple arteries anastomose in the nasal cavity?
Little areas/Kiesselbach plexus
What is the nasolacrimal duct?
Drains tear fluid from medial eyelid to the inferior meatus
What are the 4 paranasal air sinuses & where do they sit?
- Frontal - in frontal bone
- Ethmoid - air cavity between nasal cavity & orbit
- Maxillary - in cheek
- Sphenoid - midline
What epithelium line sinuses?
Respiratory mucosal epithelium
How does mucous drain from sinuses?
With gravity, except maxillary sinus
What drains into the sphenoethmoid recess?
Sphenoid sinus
What drains into the hiatus semilunaris?
Frontal, maxillary & most of ethmoid
What is peri-orbital cellulitis?
Orbital plate is a very thin piece of bone - ethmoid sinusitis can spread as soft tissue infection to the orbit
What is the sensory innervation of the nasal cavity?
Trigeminal -
- CNVa - tissues around the eye
- CNVb - maxillary
- CNVc - mandibular division
Also CNI - olfactory
What is the sensory innervation of the sinuses?
All from CNVa apart from maxillary from CNVb
What is the pinna of the ear?
The outer structure formed from cartilage & freshy lobule
What is the external acoustic meastus
Leads to tympanic membrane
When performing otoscopy, what would you do differently in adults compared to children?
In adults - pull ear postero-superiorly
In children - pull ear postero-inferiorly - tube not fully devloped
What are the 3 layers of the tympanic membrane & the innervations?
- Skin (CNVc + X)
- Mesoderm
- Respiratory mucosa (CNIX)
When performing otoscopy, where would you expect the cone of light to shine on the tympanic membrane?
Antero-inferiorly
Towards bottom right in R ear
Is the tympanic membrane concave or convex normally?
Concave
What does CNVIII vestibulocochlear nerve innervate & what are its function?
Vestibular system & cochlear.
Hearing, balance, eye movement in relation to head
What is the sensory innervation of the ear?
- Back - CN II + III
- Front - CNVc
- Also CN VII + X
Pain can be referred to the ear from what regions and via which nerves?
- CNVc - manible, teeth
- CNX - laryngopharynx, larynx, cardiac
What structures are in the middle ear?
Ossicles & eustacian tube
What are the 3 bones of the ossicles?
Stapes, incus & malleus
What is the function of the ossicles?
Conduct vibrations of tympanic membrane to oval window – amplifies signal so you can hear quiet sounds
What type of joints are in the ossicles?
Synovial joints
What are the two muscles to control oscillatory range & what do they do?
- Tensor tympani - Contracts & tenses tympanic membrane – reduce how loud sound is
- Stapedius - stop stapes from moving so much to reduce sound
What is hyperacusis?
CNVII lesion damages innervation to stapedius - sound is too loud
What is the function of the eustacian/auditory/ pharyngotympanic tube?
- Equalise pressure during swallowing
- Drain mucus of middle ear
What is the suprameatal triangle?
Access point for mastoid/tympanic antrum (drill through temporal bone)
What is mastoiditis?
Ear infections can track into mastoid air cells (in mastoid process – another sinus).
Can be extreme and erode through bone + skin
How is the eustacian tube opened when swallowing?
- Tensor veli palatini
- Levator palatini
- Salpingopharyngeus
What is the cochlear of the inner ear responsible for?
Converting vibrations into neural signals
Vibrations transmitted to perilymph via vestibular membrane
What is acute otitis media?
Infection spread from nasopharynx to middle ear.
Pain & swelling of tympanic membrane.
What is glue ear (secretory otitis media)?
Blockage of eustacian tube - persistant mucoid accumulation –> conductive hearing loss
What happens in auricular sinus?
Can be quiescent or become infected, form cysts or discharge
What nerve is being tested in the Rinne’s & Weber’s test?
CNVIII - testing cochlear component
What is Rinne’s test?
Hold tuning fork on mastoid process until stop hearing it and then hold to external acoustic meatus (EAM).
Air conduction should be better than bone conduction.
Conductive deafness - no sound heard at EAM
What is Weber’s test?
Hold tuning fork on forehead.
Conductive deafness - sound loudest in affected ear.
Sensorineural deafness - sound loudest in normal ear
