Ear, Nose & Throat Flashcards
What are the functions & features of the auricle & external auditory meati?
What glands are found in the EAM?
Auricle/pinna funnels sound towards the EAM and helps localise sounds
EAM is the tube that transits sound towards the tympanic membrane.
Lateral part is cartilaginous, medial part is bony
Lined by hair skin and cerumen glands (produce wax)
What are the features of the tympanic membrane?
What space does it communicate with that is associated with infection?
Concave externally (laterally) and has a cone of light in the antero-inferior quadrant. If infection/pressure builds up, changes shape of membrane & alters cone of light
The handle of the malleus attaches to the medial (internal) surface of the tympanic membrane with the tympanic cavity
Above the tympanic membrane is the epitympanic recess where there is communicate with the air cells of the mastoid process of the temporal bone. Middle ear infection can lead to mastoiditis
What is the arrangement & purpose of the ossicle bones?
Handle of malleus attached to tympanic membrane and head attached to incus
Incus attached to stapes
Base of stapes covers the oval window of the petrosous part of the temporal bone
Synvovial joints between them allow movement
Sound waves vibrate the tympanic membrane and the this movement is transmited through the middle ear by the ossicle bones to the inner ear
What are the positions of the oval & round windows?
What is the promontary & their relation to it?
Stapes sits on the oval window which is in the petrous part of the temporal bone
Round window just below it - opening for inner ear to the atmosphere to allow equalisation of pressure generated by ossicle bone vibrations
Promontary = turn of cochlear pushing on the tympanic membrane
Oval window is above it
Round window is below it
What are the functions of the tensor tympani muscle & stapedius muscle?
What is the nervous supply?
Dampen the amplitude movement of the ossicle bones in high pitched sounds to protect the tympanic membrane
Tensor tympani - anterior wall, attaches to malleus, trigeminal nerve (CN 5)
Stapedius - posterior wall, attaches to stapes, facial nerve (CN 7)
Where is the auditory/estachian tube located/positioned?
How is this different in children & whats the consequence?
What is its function?
What happens if it is blocked? Why is air travel not advised?
Auditory tube projects anterio-inferior to the nasopharynx
It is shorter and more vertical in children - increases risk of middle ear infections as bacteria from URT can more easily ascend the tube to the ear
Purpose for equalisation of pressure between middle ear & atmosphere
Drainage
If blocked there can be inflammation that affects movements of ossicle bones - affects hearing
Pain and potential rupture of TM if can’t equalise pressure - more likely to occur with air travel
What is the course of the facial nerve through the middle ear?
What does the chorda tympani do & what is its route?
The facial nerve enters the petrous part of temporal bone through the IAM, running in the facial canal and passing over the middle ear to exit the bone through the stylomastoid foramen
Before it passes over the middle ear it gives off the chord tympani
CT runs through the middle ear (posterior) aspect, going under the incus & over the malleus, emerging through a small hole in the temperomandibular joint and enters the oral cavity with the inguinal nerve
CT supplies anterior 2/3s tongue for taste and parasympathetic fibres to salivary glands (all except parotid) and lacrimal gland
What is the relation of the internal carotid artery to the middle ear?
What occurs in middle ear infection?
The internal carotid runs immediately beneath the middle ear
In infection, the pulsations of the artery can be heard as throbbing of the ear
What is the anatomical relation of the ethmoid bone to the brain/meninges and what is the clinical significance?
Cribiform plate of ethmoid bone located directly beneath the ventral aspect of the frontal lobe
Broken nose can introduce route of infection from nasal cavity to the meninges
Can allow bleeding from nasal cavity to access meninges - subdural haemorrhage
There can also be leakage of CSF through the nose (Rhinorrhea)
What are the bony & cartilaginous parts of the nose?
Bony = nasal bone, vomer, palatine bone, part of maxillary bone and cribiform plate
Cartilagenous parts = nasal septa, lateral and alar cartilages
What is the difference in lining and epithelium within the vestibule and remaining MEDIAL aspect of the nasal cavity?
Vestibule is opening of the nose, just inside of nostrils
Lined by hair and skin (not mucosa)
Vestibule border becomes mucous membrane
Highly vascular, warms and humidifies air
Top 1/3 and bottom 2/3 of medial aspect of cavity lined by different epithelium
Top - olfactory epithelium
Bottom - respiratory epithelium (ciliated columnar)
Where are the conchae found?
What are their function?
What clinical feature are they associated with?
Conchae are the individual turbinate bones that project off the LATERAL wall of the nasal cavity
Covered with vascular mucous membrane
They create turbulent air flow so air is trapped in cavity to allow warming & humidification
Occupy most of nasal cavity, when they are inflamed they lead to a blocked nose
What is the space beneath each conchae bone?
What opens into each of them?
There are meati (spaces) associated with each conchae - superior, middle and inferior
The paranasal sinuses open into the superior & middle meati
The nasolacrimal duct opens into the inferior meatus - drains fluid from lacrimal duct - get a runny nose when you cry
What are the 4 paranasal sinuses?
What is there nervous supply?
Where is pain referred?
Spaces in bones surrounding the nasal cavities
Frontal, Ethmoid, Sphenoid - supplied by V1, pain referred to skin of forehead
Maxillary - supplied by V2, pain referred to cheek bones
Located high on maxillary bone, posterior to the nasal cavity. Fluid drains and settles with gravity. Can’t escape sinus unless stand or head (allow gravity to drain) or physically drain it
What makes up the floor of the mouth?
Mandibular bone
Deficient inferiorly, so mylohyoid muscle completes floor inferiorly
Mylohyoid bone attaches anteriorly to the mandible and posteriorly to the hyoid bone
It allows attachment for many other muscles, including the geniohyoid bone and the digastric muscle
