Flashcards in Other HNNA Deck (34)
Which 2 cranial nerves pass through the internal acoustic meatus?
What is the function of the vestibulocochlear nerve in the ear?
Special sensory for hearing and balance
What is the function of the facial nerve in the ear?
Motor - supplies stapedius muscle (nerve to stapedius).
General sensory - small part of the external ear
How can infection spread from the middle ear to mastoid air cells, causing mastoiditis?
Spreads from middle ear through mastoid antrum via the opening called the aditus.
What type of epithelium is found in the external acoustic meatus?
Stratified squamous - continues onto the lateral surface of the tympanic membrane
What are the 2 muscles involved in the protective acoustic reflex?
Tensor tympani and stapedius - they contract when there is excessive vibration.
What are the 3 ossicles called?
Malleus, incus and stapes.
What is the function of the ossicles?
Transmit vibrations from the tympanic membrane to the oval window of the cochlea
How can infection spread from the nasopharynx to the middle ear?
Via the Eustachian tube.
What are the main functions of the eustachian/pharyngotympanic tube?
Drainage of mucous into the nasopharynx.
Equalisation of pressure in the middle ear with the atmosphere.
Describe how we hear?
Auricle and external auditory canal focus and funnel sound waves towards the tympanic membrane, which vibrates.
Vibration of he ossicles and movement of the stapes at the oval window sets up vibrations in the cochlear fluid, which are sensed by stereocilia. Movement of stereocilia in the organ of Cortisol triggers action potentials in the cochlear part of CNVIII.
What is the Rinner's test?
Hold tuning fork in air and on mastoid bone and see which is louder.
What is weber's test?
Hold tuning fork in the midline on head.
Which 4 cranial nerves carry pre-ganglionic parasympathetic neurones?
III, VII, IX and X
Which cranial nerve do post-ganglionic parasympathetics hitch hike along?
Trigeminal nerve (although it is not classed as having parasympathetic fibres as it didn't carry them out of the brainstem).
What is Horner's Syndrome?
Symptom triad when there is damage to the sympathetic trunk:
Mitosis - excessive contraction of the pupil.
Anhydrosis - inability to sweat normally
Give 2 pathologies that are associated with Horner's Syndrome.
Carotid artery dissection - separation of the layers of the artery wall supplying blood to the head and neck.
Pancoast tumour - lung cancer in the apex of the lung, can compress a sympathetic ganglion.
Where do pre-ganglionic sympathetic neurones synapse?
The sympathetic chain
What do post-ganglionic sympathetic neurones hitchhike along?
Blood vessels, mainly the internal carotid artery and external carotid arteries (wind round these blood vessels to form the sympathetic plexus).
How do sympathetics get into the orbit to innervate muscles of the eye?
Hitchhike along the opthalmic artery (branch of ICA) to get into the orbit.
Why do you often get ear pain when you have a sore throat?
Referred pain - branches of the glossopharyngeal nerve supply sensory to both the throat and ear.
What is an orbital blow out fracture?
When the intraorbital pressure rises e.g. Due to a punch, it can fracture the floor of the orbit. Orbital contents can spill out into the maxillary air sinus.
What is a stye?
Blockage of the sebaceous glands in the eye.
What is a Meibomian cyst?
Blockage of the Meibomian glands in the eye - painful white head visible on the edge of the eyelid.
What divides the orbit into pre-orbital and post-orbital zones?
The orbital septum.
What is periorbital cellulitis?
Infection superficial to the orbital septum, ocular function remains unafffected.
What is orbital cellulitis?
Infection in the post-septal orbit, affects the optic nerve and extra-ocular muscles.
What part of the eye does the conjunctiva not cover?
Covers the sclera, but doesn't cover the cornea (continuation of the sclera)
What is conjunctivitis?
Inflammation/infection of the conjunctiva.
What is subconjunctival haemorrhage?
Haemorrhage from the blood vessels in the eye.
What is presbyopia?
The lens becoming stiffer as we age and less able to change shape. Means that we can't focus on near objects.
What is a cataract?
Increased opacity of the lens due to degradation of proteins.
What is glaucoma?
When the optic nerve is damaged secondary to blocking of drainage of aqueous humour from the anterior chamber of the eye - causes a rise in intra-ocular pressure and damage to optic nerve.