The Ear Flashcards
Which bone is the ear situated around and what are its 4 parts?
The temporal bone houses many of the structures of the ear as well as constituting a large proportion of the lateral side of the skull. It is split into 4 parts: squamous, petromastoid, tympanic plate and styloid process.
What parts of the temporal bone are the middle and inner ear in? Which nerves pass through here?
The petromastoid part contains the middle and inner ear. It is pierced by the internal acoustic meatus transmitting the facial and vestibulocochlear cranial nerves.
What is the mastoid process?
The mastoid process is a large landmark to which several muscles are attached. The mastoid antrum communicates into this process by mastoid air cells. Middle ear infections can spread by this route to cause mastoiditis.
What kind of symptoms can ear problems present with?
Symptoms of Diseases involving the ear: pain, discharge, hearing loss, tinnitus, vertigo and facial palsy.
What makes up the external ear?
The External Ear containing the pinna (auricle), external auditory meatus and lateral surfaces of the tympanic membrane.
Describe the pinna?
The pinna is made of cartilage, skin and fatty tissue, it’s function is to collect transmit and focus sound waves onto the tympanic membrane. The outer elastic cartilages are arranged in curved ridges the outer being the helix, the anti-helix, the tragus a small flap guarding the external acoustic meatus and an anti-tragus opposite it covering the concha, (ear lobe is manly fat and is called the lobule).
What is Ramsay hunt syndrome?
Ramsay hunt syndrome – shingles of the facial nerve causing drooping of one side of the face and vesicles in the ipsilateral ear.
What is a pinna haematoma?
A pinna haematoma occurs secondary to blunt injury and is common in contact sports, causing an accumulation of blood between cartilages and perichondrium. This deprives the cartilage of its blood supply and causes pressure necrosis of the tissue. Treatment includes: prompt drainage, measure to prevent re-accumulation and re-apposition of the two layers are necessary. If left untreated it causes fibrosis and new asymmetrical cartilage development also known as cauliflower ear (complication not a diagnosis).
What is the external acoustic meatus?
The external acoustic meatus is the ear canal.
This is a skin‐lined cul‐de‐sac. Sigmoid shape: need to pull ear up and back to straighten when examining. A cartilaginous (outer 1/3) and bony part (inner 2/3). Self‐cleaning function, to keep it clear. Arrangement of hairs and production of wax (cartilaginous part). Prevent objects entering deeper into ear canal. Also, aid in desquamation and skin migration out of canal
Why might there be excess wax?
Otitis Externa infection and inflammation of the ear canal – known as swimmer’s ear
Describe the structure you might see on a tympanic membrane with an otoscope?
In the middle the handle of the malleus should be visible. To the left of this is the parsa tensa which is the tauntest part of the tympanic membrane. Above the malleus is the pars flaccida or the attic which is the least taunt part of the membrane. A cone of light from the otoscope being used can also be seen and this poitn down towards the feet.
What makes up the middle ear?
The Middle Ear containing the Ossicles and air filled cavity. The Ossicles include the malleus, incus and the stapes. Malleus is in contact with the tympanic membrane and incus which itself is in contact with the stapes. These articulations are synovial. They function to amplify vibrations from the tympanic membrane to the cochlea via the oval window.
What is the stapedius muscle?
The stapedius muscle is innervated by a branch of the facial nerve and dampens the stapes when we know a loud noise is coming.
Where in the middle ear are the Ossicles located?
Right at the top in the epitympanic cavity is where the Ossicles are.
What is the function of the Eustachian tube?
The middle ear is connected to the nasopharynx by the eustachian tube or pharyngotympanic tube which equilibrates pressure within the middle ear with the atmosphere and is also important in ventilation of and drainage of mucus from the middle ear. It is normally closed but opens when you swallow by the pull of the palate muscles.
What is otitis media with effusion?
Otitis media with effusion (glue ear) – Not an actual infection just a build-up of fluid and negative pressure in middle ear – Due to Eustachian tube dysfunction and cells in middle air absorbing air. Can predispose to infection. Decreases mobility of TM and Ossicles affecting hearing – Most resolve spontaneously in 2‐3 months but some may persist requiring grommets (small ventilator tube through the tympanic membrane.
What is otitis media?
Acute middle ear infection that is more common in infants and children than in adults. Otalgia (infants may pull or tug at the ear) and other non‐specific symptoms e.g. temperature, red +/‐ bulging TM and loss of normal landmarks. It is more common in children because the Eustachian tube is more horizontal allowing easier passage of infection from the nasopharynx and is easier to block due to its size.
What complciations are there of otitis media?
Complications of otitis media
Tympanic membrane perforation, facial nerve involvement, rarer but potentially life‐threatening complications include: Mastoiditis, Intracranial complications, Meningitis, Sigmoid sinus thrombosis and brain abscess.
What is mastoiditis?
Mastoid air cells communicate with middle ear cavity as they are involved in helping to equilibrate middle ear pressures. Provides a potential route for middle ear infections to spread into the mastoid bone (mastoid air cells). Behind the ear will be swollen and the affected ear will be pushed forward.
Which nerve is closely associated with the ear?
Facial nerve, in particular chorda tympani branch, runs through middle ear cavity. Facial nerve may be involved in pathology involving the middle ear. Chorda tympani branch runs over the tympanic membrane and provides taste.
What is cholesteatoma?
Rare, but should not be missed. Painless otorrhea to more serious neurological complications. Usually secondary to chronic/recurring ear infections and blockage of ET – Creates a sucking, negative pressure, drawing eardrum inwards – Can lead to small pocket forming. Skin cells get trapped, collect and continue to grow in this small pocket within middle ear. Not malignant but slowly grows and expands, eroding into structures e.g. Ossicles, mastoid bone and cochlea.
What makes up the inner ear?
The Inner Ear also known as the labyrinth containing the vestibular apparatus and cochlea – a series of channels hollowed out of the petrous temporal bone. The cochlea converts sound vibration into an electrical signal (action potential) which is perceived as sound. The vestibular apparatus is involved in maintaining our sense of position and balance.
What is the function of the cochlea?
The cochlea is our organ of hearing. It is fluid filled tube. Movements at the oval window set up movements of the fluid in the cochlea. Waves of fluid cause movement of special sensory cells within the cochlear duct which fire action potentials.
What is sensorineural hearing loss?
Sensorineural hearing loss i.e. the problem is with the facial nerve or the inner ear.
