Week 1 - B - Day 1, Afternoon Instant Anatomy Tutorial Flashcards
What are the two parts of the orbicularis oculi?
Orbital part and Palpebral part (eyelid)
What lies immediately posterior to the orbicularis oculi muscle? Before even reaching the conjunctivae
The orbital septum
What are the layers of the eyelid?
skin subcutaneous tissue orbicularis oculi orbital septum and tarsal plates, palpebral conjunctiva
Which layer of the eyelid has the glands that produce the oily/lipid part of tears?
The tarsal plates - produce meibum
Inflammation posterior to the orbital septum is sight threatening What is this known as?
Oribital cellulitis (opposite = preseptal cellulitis)
The inner surface of the eyelids is covered by the palpebral conjunctiva. What is the type of conjuctivae lining the eyeball known as?
Known as bulbar (ocular) conjunctivae
Bulbar conjunctiva
- mucous membrane covering ant surface of eyeball around cornea
- stratified epithelium containing goblet cells
- reflects onto inner eyelids (palpebral conjuctiva)
The palpebral part of the orbicularis oculi is involved in normal blinking. What is the orbital part involved in?
Closing the eyes tightly
What muscle assists the levator in elevating the top eyelid. It receives sympathetic innervation which may be compromised in Horners syndrome causing ptosis?
Muller’s muscle (superior tarsal muscle)
Name the different coloured bones that contribute to the orbit of the eye?
Red - frontal Purple - maxilla Blue - zygoma Green - lacrimal Beige - ethmoid Yellow - sphenoid
Which bone of the floor of the cranial cavity is the superior orbital fissue located in?
It is located in the sphenoid bone
What are the three way for structures to enter the orbital cavity?
Optic canal Superior orbital fissue Inferior orbital fissure
What does the Superior orbital fissure transmit into the orbit?
Oculomotor nerve (III) Trochlear (IV) Lacrimal/frontal/nasociliary branches of Ophthalmic nerve (V1) Abducent nerve (VI) Superior ophthalmic vein
What branch comes of the ophthalmic nerve (CN V1) to innervate the upper half of the nasal cavity?
The anterior ethmoidal nerve
The tear has three layers How does the tear film have antibacterial properties?
It has lysozymes - they are found in phagocytes and produce enymes to digest bacteria
What are the three layers of the tear film?
Outer - Oil (lipid) layer - due to the meibum produced by the tarsal (meibomian) glands Middle - Water (aqueous) layer Inner - Mucin layer
Which layer of the tear film contains the lysozymes? The lysozymes are part of the fluid produced by lacrimal gland
The aqeuous layer
Tears have a basal and reflex secretion What is required for the reflex tear production?
An intact trigeminal nerve
What nerve is for snesation when the eye needs tears? What nerve provides the parasympathetic supply to the lacrimal gland to produce tears?
CN V for sensation The CN VII - facial nerve via the greater petrosal nerve
The palpebral conjunctiva is more vascular than the bulbar What can be seen on the palpebral conjuctivae?
Follicles and papillae can be seen on the palpebral conjunctiva
What does the palpebral conjunctivae contain that secretes part of the tear film?
Contains goblet cells which secrete the mucin (inner layer of tear)
Epithelium bowman’s membrane stroma Descemet’s membrane endothelium What are these the 5 layers of?
The five layers of the cornea
How does the endothelium maintain transparency of the cornea?
Maintains transparency by pumping fluid out of the stroma
What can happen to the endothelium if pressure in the eye goes up?
The endothelium will not function properly causing misty vision in the eye as there is a fluid build up
What age does the lens of the eye start deteriorating causing cloudy vision?
At 23 years of age Condition known as cataracts
Cataracts happen when protein builds up in the lens of your eye, making it cloudy. This prevents light from passing clearly through the lens, causing some loss of vision. New lens cells form on the outside of the lens, and the older cells are compacted into the center of the lens, forming the cataract. Catarcts is due to the lens not being able to rid of the old cells quick enough
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How is the lens attached to the ciliary body?
Zonules attach to the suspensory ligaments of the lens
What is the vascular layer supplying blood and nutrition to the eyeball?
The choroid (uvea)
What is produced by the filtration of blood in the capillary network of the ciliary processes?
Aqueous humour
Where does the aqueous humour flow from?
The aqueous humour flows from the posterior chamber to the anterior chamber of the eye - this sits in front of the iris but behind the cornea
What makes the aqueous humour allow for good optical clarity?
Its low protein content
What is inflammation of the middle layer of the eye known as?
Uveitis = Different autoimmune conditions can cause uveirits Can be part of reiters arthritis - uveitis, reactive arthritis, ureithritis
What tumour of the apex of the long can cause Horner’s syndrome? What are the four signs of horner’s syndrome?
Pancoast tumour Ptosis - drooping of eyelid Miosis - constricted pupil Enopthalmos - sunken eye Annhydrois - lack of facial sweating
Distant vision- lens is flatter so the refraction is less and can see further images, ciliary muscles are relaxed What is the accomodation reflex from seeing something from far to close?
- When changing from looking far to close, the ciliary muscles contract, thus the zonule fibres are relaxed and the lens becomes wider - having a greater refraction and seeing things that are closer
- Also bilateral conversion of the eyes
- Also sphincter pupillae contract
What happens to the ability to accomodate as we get older? What are zonule fibres also known as?
Ability to accomodate decreases Zonule fibres also known as supensory ligaments of the lens
What is the third cranial nerve? What extra-ocular muscles does it supply? What does a palsy of the third nerve look like?
Oculomotor - supplies inferior oblique, superior, medial and inferior rectus Palsy has the eye pointing down and out as the trcohlear nerve supplying the superior oblique still works Also the person will have ptosis, fixed dilated pupil (parasympathetics to constrictor muscles of eye dont work)
The trochlear nerve is unique in that it arises from the dorsal aspect of the brainstem and crosses over If their is a left trochlear palsy, what muscle will have a pasly?
The muscle on the contralateral side so the right superior oblique muscle
- eyes look upwards, vertical diplopia, cannot look down and out head held tilted. What nerve palsy is this? Why is there a head tilit?
Fourth nerve palsy To compensate for the double-vision resulting from the weakness of the superior oblique, patients characteristically tilt their head down and to the side opposite the affected muscle * ie if Right SO palsy, patients head will tilt left
The trochlear nucleus lies below the cerebral (sylvian) aqueduct This is in the brainstem How does the nerve enter the eye?
The nerve enters the eye through the superior orbital fissure in the sphenoid bone
What conveys the sensory (afferent) arm of the blink (corneal) reflex?
The opthalmic division of the trigeminal nerve
horizontal diplopia, eyes medially deviated, & cannot move laterally from midline. COnvergent squint (start in) What nerve is this due to and how does the horiontal diplopia work?
Due to the CN VI (abducent) Controls the lateral rectus and therefore the eyes will not be centrally focussed causing different images on the horizontal plane
The 6th nerve passes through the middle of the cavernous sinus, not the wall What are the other nerves of the carvernous sinus? What is the artery? (O TOM CA)
- Oculomotor
- Trochlear
- Opthalmic
- Maxillary
- Abducent
- Internal Carotid artery
Usually the nasociliary branch of the opthalmic division of the trigeminal nerve supplies the tip of the nose What sign is Vesicles on the tip of the nose, or vesicles on the side of the nose? What does it tell you?
It is called Hutchison’s sign Tells you the eye has been affected as it has gone past the ophthalmic nerve
The muscles are attached to a common tendinous ring at the back of the eye What nerve and artery travels in the middle of this ring? Which extraocular muscles are located outside the tendinous ring?
Optic nerve alongisde the opthalmic artery The levator palpabrae superioris, the superior oblique and also inferior oblique as this attaches to the maxilla Only the 4 rectus muscles are attached to the common tendinous ring
The optic nerve sheath is attached to the common tendinous ring, why optic neuritis causes pain on eye movements What muscle is commonly trapped in a blow out fracture of the orbit?
The inferior rectus muscle
The retina have rods and cones Where are rods not found? Where are cones found in the highest density?
rods are found everywhere in the retina, except in and near the fovea. Cones are found in highest density in the fovea
What is the end artery supplying the eye? An emboli that lodges hear can cause loss of vision
The opthalmic artery is the end artery supplying the eye
What is the back of the eye known as? In fundoscopy what region of the eye do the quadrants go through?
The fundus Thq quadrants go throug the fovea of the eye
The superior ophthalmic vein leaves the eye via the Superior orbital fissure The vein drains into the cavernous sinus Why do retinal veins appear thicker than the retinal arteries?
Retinal veins appear thicker than retinal arteries due to arteries having a muscular tunic
The cornea has a rich supply of free nerve endings The long and short ciliary nerves become part of the nasociliary nerve of the trigeminal - sensory of cornea What is the branch of the nasociliary nerve entering the nasal cavity via the anterior ethmoidal foramen?
The anterior ehtmoidal nerve
Retinal detachment occurs when the thin lining at the back of your eye called the retina begins to pull away from the blood vessels that supply it with oxygen and nutrients. What people is retinal detachment more common in?
More common in people with short sight as they have big eyes
The inferior wall of the orbit is the most vulnerable to blunt trauma People with inferior wall fracture often complain upon pain on upgaze due to which muscle being trapped?
The inferior rectus muscle
Rods are involved in seeing in dim light and peripheral vision What type of vision can loss of peripheral vision result in?
Tunnel vision
Age-related macular degeneration (AMD) is a painless eye condition that causes you to lose what?
Causes you to lose central vision usually in both eyes
