ENT Flashcards
fluid level behind drum, retracted drum, dull colour
otitis media with effusion
difficulty at school, have to shout to hear
glue ear
feeling of fullness in ear
meniere’s disease
loss of corneal reflex, sensorineural hearing loss, vertigo, tinitus
acoustic neuroma (vestibular schwannoma) associated with NF2
vertigo on rotation movement of head
BPPV
battle sign
bruising on the skull over mastoid process, temporal bone fracture
pearly white on otoscopy and foul, cheesy discharge
cholesteatoma
saddle nose
wegner’s granulomatosis (granulomatosis with polyangiitis)
BPPV key features
vertigo seconds to minutes
dx with hallpikes
tx with epley manoeuvre
Bell’s palsy
compression of facial nerve
why avoid adrenaline near the nasal cartilages?
cartilage is avascular, chondrocytes receive nutrition through diffusion of nearby arteries. In the nose these are end arteries. Vasoconstriction due to sympathetic stimulation can lead to necrosis
What forms the roof of the nasal cavity?
cribriform plate of ethmoid bone
What forms the lateral walls of the nasal cavity?
superior and middle conchae of the ethmoid bone
What forms the septum of the nasal cavity?
perpendicular plate of the ethmoid bone
What forms the inferior conchae?
inferior conchae bone
What are the 3 mucosa of the nosal cavities?
keratinised stratified squamous
respiratory mucosa (pseudostratified ciliated columnar)
Olfactory mucosa
Where does the olfactory tract end?
temporal lobe
What is somatic sensory supply to nose?
anteriorsuperiorly: ophthalmic CNV1
Posteriorinferiorly: maxillary CNV2
What is kiesselbach’s area and where is it?
common site of nose bleeds due to high density of arterial anastomosis
nasal septum
What areteries supply the nose?
facial and maxillary (from external carotid)
ophthalmic (from internal carotid)
Where does frontal sinus drain?
middle meatus (under the middle concha)
Where does the ethmoidal sinuses drain?
superior and middle meatus
Where does the sphenoidal sinus drain?
sphenoethmoidal recess
Where does the maxillary sinus drain?
middle meatus
Where does the nasolacrimal duct drain?
inferior meatus
What is the H shaped structure that is thin and weak and what bones connect here?
pterion
frontal, parietal and temporal
What CNs exit/enter the skull in anterior cranial fossa?
CNI
What CNs exit/enter the skull in middle cranial fossa?
CNII - CNVI
What CNs exit/enter the skull in posterior cranial fossa?
CNVI- CNXII
Where is the internal acoustic meatus and what passes through it?
petrous part of the temporal bone (passage from posterior cranial fossa into inner ear)
passage for CNVII and CNVIII
Contains vestibular ganglion and labyrinthe artery
Functions of external, middle and internal ear?
external: collects and conveys sound waves to tympanic membrane
internal: amplifies and conducts sound waves to inner ear
internal: converts sound waves into fluid waves and then APs and conducts to brain
What makes up the external acoustic meatus?
1/3rd cartilage
2/3rd bone
covered in skin
What features are you looking for in a normal tympanic membrane?
pars flaccida: thin part of membrane superiorly
pars tens: thick part of membrane posteroinferiorly
umbo: most inwardly depressed part (handle of the malleus)
cone of light: usually anteroinferiorly
What causes referred pain?
when two different locations are innervated by the same nerve the brain can sometimes confuse where the original pain stimulus is coming from
Why can tonsillitis cause earache?
spread of infection through eustachian tube
or referred pain (CNIX supplies sensory middle ear, eustachian tube, nasopharynx, oropharynx, tonsils)
What is the adenoid?
pharyngeal tonsil (just above and behind the uvula)
What are the ossicles?
malleus
incus
stapes
What provides general sensory innervation to tympanic membrane?
external mainly CNV3
internal CNIX
What forms the oval window?
base of the stapes
What kind of epithelium line the outer ear and middle ear?
outer: keratinised stratified squamous with sebacous glands and ceruminous glands (ectoderm)
middle: cilliated pseudostratified columnar (endoderm)
What brain cavity is above the middle ear?
middle cranial fossa
Where does the facial nerve connect to CNS?
brainstem (junction between pons and medulla)
How does vibration of the stapes transmit sound?
vibration of stapes at oval window creates pressure waves in the perilymph
hair cells in the cochlea are moved and neurotransmitter released and APs fired to the brain down the cochlear nerve
pressure waves descend and become vibrations at the round window dampening the signal
What are the two points of entry between inner ear and middle ear?
oval window (vibrations enter) round window (allows fluid in cochlea to vibrate in a closed system)
What is function of eustachian tube?
equalise pressures with middle ear and environment
drain secretion of middle ear mucosa
What is the resting state of eustachian tube?
cartilaginous portion of the tube is closed at rest but opened by palatine muscles
What does dysfunction of the eustachian tube cause?
middle ear negative pressure
Where are low sounds perceived?
apex of cochlear
Where are high sounds perceived?
base of cochlear
What is function of vestibular system?
balance and sense of orientation (spatial orientation)
What causes dizzyness?
endolymph fluid in semicircular canals still moving when you are stationary
What is anosmia?
inability to smell
What is hyposmia?
reduced smell
What is dysomia?
altered sense of smell
What is aguesia?
loss of taste
How is smell sensed?
odorants bind to the cilia of olfactory rods that are projected on the olfactory mucosa and alter ion channels creating APs.
How is taste sensed?
binding of tastants to receptor cells alters ionic channels and depolarises cell creating an AP. Different receptors to different structural components of food are located in different areas
What are taste buds?
made up of sensory receptor cells and support cells
What is the life span of taste receptor cells and olfactory receptor cells?
10 days
2 months
Why does webers test locailse to the affected ear in conductive hearing loss?
the middle ear on the affected side is not functioning properly and masks ambient noise of the room while the normal functioning inner ear picks up bone conduction. It appears louder than the unaffected ear which has sounds of the room mixed in with bone conduction.
Why does the webers test localise away from the affected ear in sensorineural hearing loss?
the inner ear of the affected ear does not detect bone conduction
