EYE AND EAR Flashcards
WHAT ARE THE 4 MAIN OPENINGS IN THE ORBIT AND WHAT DO THEY TRANSMIT
nasolacrimal canal - nasolacrimal duct
optic canal - optic nerve CN II, opthalmic artery
inferior orbital fissure - inferior opthalmic vein
superior orbital fissure - superior opthalmic vein , CN III occulomotor (superior and inferior branches) , CN V1 (frontal , lacrimal and nasocilliary branches) , CN VI abducens
RETROBULBAR FAT
present in orbit , supports eyeball
WHAT IS CONTAINED WITHIN THE OPTIC NERVE
central retinal artery and central retinal vein
AMAUROSIS FUGAX
painless temporary loss of vision in one eye due to occlusion of central retinal artery
occlusion can lead to permanent loss of vision
WHY DOES RAISED INTRACRANIAL PRESSURE AFFECT THE EYE
meninges and subarachnoid space extend from skull around optic nerve to sclera
raised intracranial pressure affects eye due to CSF in subarachnoid space.
slows retinal venous drainage via central retinal vein causing papilloedema
IS MEDIAL VISION SUPPLIED BY IPSI OR CONTRALATERAL FIBRES OF THE OPTIC NERVE
medial vision is supplied by the ipsilateral side
lateral vision is supplied by the contralateral side
WHAT WOULD A LESION AT THE OPTCI CHIASM RESULT IN
‘tunnel vision’
fibres crossing to the contralateral side would be affected and these fibres are meant to go on and supply lateral vision on each side
WHERE IS THE LACRIMAL GLAND LOCATED
in the upper lateral corner of the orbit
FUNCTION OF THE LACRIMAL GLAND
secretes tears into conjunctival sac (recess between eyeball/cornea and eyelid) which are then dispersed across the eyeball when blinking - requires orbicularis oculi to be functioning correctly
DESCRIBE THE DRAINAGE OF TEARS
Drain through 2 holes in upper and lower eyelid called lacrimal punta
punta drain into ducts called canaliculi which drain into the lacrimal sac
lacrimal sac drains into nasolacrimal duct which drains into inferior nasal meatus
DESCRIBE THE PARASYMPATHETIC CONTROL OF THE LACRIMAL GLAND
preganglionic parasympathetic fibres come from CN VII via the greater petrosal nerve
synapse in the pterygopalatine ganglion
post ganglionic parasympathetic fibres travel with zygomatic nerve of CN V2 then lacrimar nerve of CN V1
WHAT ARE THE 7 EXTRAOCULAR MUSCLES
4 recti: superior, inferior, lateral and medial
2 oblique: superior and inferior
levator palpebrae superioris
LEVATOR PALPEBRAE SUPERIORIS
first muscle found during superior dissection of eyeball/ orbit
elevates eyelid to keep eye open
contains both smooth and striated muscle fibres
WHAT IS THE SUPERIOR OBLIQUE TENDON PULLY CALLED
trochlea
COMMON TENDINOUS RING
meeting of all posterior recti tendons and superior oblique found posterior to orbit
WHAT NERVES SUPPLY THE EXTRAOCULAR MUSCLES
LR6 SO4 AO3
lateral rectus CN VI
superior oblique CN IV
all others CN III
WHAT MAY A DILATED PUPIL INDICATE
mydriasis
damage to parasympathetic control
WHAT MIGHT A DROOPED UPPER EYELID INDICATE
damage to levator palpebrae superioris
WHAT MIGHT AN EYE TURNED DOWN AND OUT INDICATE
damage to CN III
only SO and LR working
WHAT ARE THE 3 LAYERS OF THE EYEBALL
sclera - outermost
choroid - vascular
retina - light sensitive
WHERE ARE THE ANTERIOR AND POSTERIOR CHAMBERS OF THE EYE FOUND AND WHAT ARE THEY FILLED WITH
They are found in the anterior eyeball
chambers are separated by the iris and communicate via the pupil
they are filled with aqueous humour
WHAT IS THE EYEBALL FILLED WITH
‘vitreous chamber’ filled with vitreous humour
CILIARY BODY
anterior extension of the choroid layer serves to form a supportive ring around the lens and iris
Contains the ciliary muscle which are attached to the lens via zonular fibres and can alter its shape
Aqueous humour is secreted by the ciliary body
WHAT CAUSES GLAUCOMA
glaucoma = fluid build up due to issue with drainage of aqueous humour
IS DILATION OF THE PUPIL CAUSED BY PARASYMPATHETIC OR SYMPATHETIC NERVE FIBRES
sympathetic
parasympathetic causes constriction of pupil
HOW DO CILIARY MUSCLES ALTER THE ABILITY FOR LONG AND SHORT VISION
ciliary muscles are connected to the lens via zonular fibres
Contracted ciliary fibres = relaxed zonular fibres therefore a rounded lens which facilitates near vision (parasympathetic)
In absence of ciliary muscle contraction , zonular muscle fibres are stretches as is the lens facilitating long vision
WHAT BONE IS THE VESTIBULOCOCHLEAR APPARATUS HOUSED
petrous part of the temporal bone
TYMPANIC MEMBRANE
separates external acoustic meatus from middle ear
held in place by fibrocartilaginous ring
healthy membrane will have cone of light present when viewed through an otoscope
AUDITORY OSSICLES
mobile chain of 3 small bones
malleus - handle attaches to tympanic membrane
incus - middle
stapes - attaches to oval window
They transmit sound collected by the auricle to the inner ear
FUNCTION OF PHARYNGOTYMPANIC TUBE
equalises air pressure in the middle ear however is a potential infection route
FUNCTION OF PHARYNGOTYMPANIC TUBE
equalises air pressure in the middle ear however is a potential infection route
WHAT IS THE EXTERNAL ACOUSTIC MEATUS LINED WITH
lateral 1/3 is cartilaginous lined with same skin as auricle (stratified squamous) - contains hair follicles and modified sweat glands which produce earwax - together hairs and earwax stop foreign bodies reaching tympanic membrane
medial 2/3 is bony and lined with thin skin continuous with the tympanic membrane
WHAT NERVE TRAVELS IN CLOSE PROXIMITY TO THE TYMPANIC MEMBRANE
chorda tympani
WHAT 3 REGIONS MIGHT A SEVERE INFECTION OF THE MIDDLE EAR SPREAD TO
IJV and ICA - would turn infection systemic
Cranial cavity - thin bone separating middle ear and middle cranial fossa
Mastoid air cells - causing mastoiditis
HOW CAN CONDUCTIVE DEAFNESS BE CAUSED BY A MIDDLE EAR INFECTION
if the ossicles are damaged
WHAT IS A COMMON CAUSE OF MIDDLE EAR INFECTIONS (OTITIS MEDIA)
obstructions in pharyngotympanic tube
WHAT ARE THE TWO PARTS OF CN VIII AND WHAT DO THEY SUPPLY
vestibular - concerned with balance, supplies semi circular canals and utricle
cochlear - concerned with hearing , supplies cochlea
