Anatomy Flashcards
Bony orbit - apex
Optic canal
Bony orbit - roof
Mainly frontal bone
Bony orbit - floor
Mainly maxilla
Bony orbit - medial wall
Mainly ethmoid bone
Bony orbit - lateral wall
Mainly sphenoid bone
Orbital rim
Base of the bony orbit
Helps protect the eye from direct trauma
Blowout fracture - which 2 bones are most likely to be affected
Ethmoid bone
Maxilla
Fractured zygoma causes which visual abnormality?
Diplopia (double vision)
- zygoma normally attaches to suspensory ligaments which help support the eyeball and hold it up
Tarsus
Eyelid
What is the name of the conjunctiva which covers the internal eyelids?
Palpebral conjunctiva
Where are tarsal glands located
Embedded in the tarsi
Function of tarsal glands
Lubricates the edges of the eyelids
Orbicularis oculi - function
Orbits around the ocular area and allows eye closing
Which nerve supplies orbicularis oculi
CN VII
2 parts of orbicularis oculi
Orbital part
Palpebral part
Orbicularis oculi - orbital part
Used to close eyes tightly
screw up eyes
Orbicularis oculi - palpebral part
Used to gently close eyes
blinking
Which muscle elevates the eyelid
Levator palpebrae superioris
Mulars muscle
Attaches from the tendon of LPS to the superior eyelid
It assists LPS in elevating the eyelid
Function of meibomian glands
Modified sebaceous glands
Prevent tears from evaporating
Where is the lacrimal gland located?
Just below the lateral aspect of the eyebrow
Sclera - definition
White area of the eye
Contains collagen fibres arranged like a meshwork
What is the conjunctiva which covers the sclera called?
Bulbar conjunctiva
Limbus
Junction between the cornea and sclera
Lacrimal punctum
Black dot on the lower eyelid
This is where lacrimal fluid drains in to
Which is more vascular: bulbar or palpebral conjunctiva?
Palpebral
The conjunctiva covers the cornea - true or false?
False
Function of the conjunctiva
Defensive barrier to foreign bodies
Good at healing lacerations in the eye
Iris
The part of the eye which gives your eye colour
Controls diameter of pupil
Pupil
Black central hole where light passes through to get to the retina
Cornea
Translucent (clear)
Avascular
Bulge
Collagen fibres are precisely arranged (optical clarity)
Which structure of the eye do you get most optical power from?
Cornea
Outer layer of the eye - type
Fibrous layer
Outer layer of the eye - constituents
Sclera
Cornea
Middle layer of the eye - type
Uvea
vascular layer
Middle layer of the eye - constituents
Iris
Ciliary body
Choroid
Inner layer of the eye - type
Retina
Inner layer of the eye - constituents
Optic disc
Macula
Fovea
Retina - function
The posterior aspect of the eye which receives and starts to interpret light coming into the eye
What is the pathway for the direction of light passing through the retina?
Ganglion cells (anteriorly) --> Photoreceptors (posteriorly)
What is the direction of signal transmission in the retina?
Posterior -> anterior direction
The signal is generated by photoreceptors
Signal is sent to ganglion cells
Optic nerve is formed
The retina has pain and light receptors. True or False?
False
- the retina has light receptors only
- if something is wrong it just flashes lights (looks like camera flashes)
Fundus location
Back of the eye
Which area of the eye is known as the blind spot?
Optic disc
- there are no photoreceptors in this area
Where does the optic nerve form?
Optic disc
Optic disc
Blind spot
Macula - function
Specialised or acute vision
- lots of cones here
Fovea - location
In the centre of the macula
Fovea - function
For most acute vision
- cones found in high density
The optic disc sits nasally/temporally?
Nasally
The macula sits nasally/temporally?
Temporally
How do you differentiate veins from arteries on a fundoscopy image?
Veins are bigger and thicker
Arteries are smaller and thinner
Layers of the retina - posterior layer
Photoreceptors (rods and cones)
Layers of the retina - middle layer
Ganglion cells
Layers of the retina - anterior layer
Axons of the ganglion cells
Anterior segment - location
In front of the lens
Anterior segment - anterior chamber
Between the cornea and the iris
Contains aqueous humour
Anterior segment - posterior chamber
Between the iris and suspensory ligaments (zonule fibres)
Contains aqueous humour
Posterior segment - location
Behind the lens
Contains vitreous body
Arterial blood supply pathway
Common carotid artery –>
Internal carotid artery –>
Ophthalamic artery –>
Central retinal artery and ciliary artery
Ciliary artery
Supplies the uvea
Which artery supplies the optic nerve head?
Posterior ciliary artery
Central retinal artery
Passes inside the optic nerve
It is an end artery
- if it becomes blocked then there is no blood supply to the retina leading to ischaemia of the retina
Which artery supplies the majority of the retina?
Central retinal artery
What causes red eyes when photo is taken with flash
Ciliary artery
Pathway of venous drainage of the eye
Superior and inferior ophthalmic veins ->
Superior ophthalmic vein ->
Cavernous sinus ->
Superficial vein of the face
Which vein drains the retina?
Central retinal vein
Everything from the right visual field hits the eye at the ____ retina of the right eye but the _____ retina of the left eye
- Nasal
2. Temporal
The temporal retina of both eyes stays MEDIAL/LATERAL?
Lateral
- i.e. doesn’t cross over at the optic chiasma
The nasal retina of both eyes stays MEDIAL/LATERAL?
Medial
Crossing over at the optic chiasma occurs with the nasal retina OR temporal retina ?
Nasal retina
Light from objects in the right visual field is processed by the ____ primary visual cortex?
Left
Light from objects in the lower visual field is processed by the ____ primary visual cortex
Upper part
Blink reflex - sensory (afferent) limb
Picks up the sensation that is being touched
AP are conducted from cornea -> trigeminal ganglion -> pons
Blink reflex - central connections between which 2 CN’s?
CNV and CNVII
Blink reflex - motor (efferent) limb
APs conducted via CNVII -> eyelid part of orbicular oculi.
this results in a blink
Where does the synapse occur in the cervical part of the sympathetic trunk
Superior cervical ganglia
What causes wide eye opening? (sympathetic or parasympathetic)
Sympathetic
What focuses the lens for near vision ? (sympathetic or parasympathetic)
Parasympathetic
What focuses the lens for far vision ? (sympathetic or parasympathetic)
Sympathetics
______ nerves dilate the pupil
Sympathetic
_____ nerves constrict the pupil
Parasympathetic
What causes lacrimation reflex tear production to occur ? (sympathetic or parasympathetic)
Parasympathetic
Dilated pupils allow MORE/LESS light to reach the retina?
More
Which muscles are responsible for dilating the pupil? and where are they located?
Dilator pupillae muscles
Location: around the external circumference of the iris
Constricted pupils allow MORE/LESS light to reach the retina?
Less
In dim light what happens to the pupil?
It dilates
In bright light what happens to the pupil?
It constricts
Mydratic pupil
a non physiologically dilated pupil
Mitotic pupil
A non physiologically constricted pupil
Which muscles are responsible for constricting the pupil? and where are they located?
Sphincter pupillae muscles
Location: around the internal circumference of the iris
Pupillary light reflex - shine torch into one eye, what happens to that eye?
CNII senses this and CN III causes pupil to constrict (direct light reflex)
Pupillary light reflex - shine a torch into one eye, what happens to the OTHER eye?
CN III causes pupil to constrict (consensual light reflex)
How does the lens attach to the ciliary body?
Suspensory ligaments (zonules)
What is another name for suspensory ligaments?
Zonules
What is the function of the ciliary body?
Produces aqueous humour
What happens to the ciliary muscle, suspensory ligaments and lens in far vision?
Ciliary muscle relaxes
Suspensory ligament tightens
Lens flattens
- to focus on object in the distance
What happens to the ciliary muscle, suspensory ligaments and lens in near vision?
Ciliary muscle contracts
Suspensory ligament relaxes
Lens becomes spherical
- to focus on near objects
Lens is spherical for NEAR/FAR vision?
Near
Lens is flat for NEAR/FAR vision?
Far
Which CN controls pupillary constriction?
CN III
Where is the lacrimal gland located?
Below the lateral aspect of the eyebrow
What does the lacrimal gland produce?
Produces lacrimal fluid (tears)
Lacrimal gland is controlled by which cranial nerve?
CNVII
Which direction does lacrimal fluid flow?
Temporal -> nasal lacrimal duct
Where does lacrimal fluid drain?
Punctum (black dot on top of the lacrimal papillae)
Lacrimal fluid always runs into the nose - true or false?
True
What is the function of lysozyme in lacrimal fluid?
Antibacterial properties
which CN tells the brain that the eye needs tears?
CNV
Which CN stimulates the lacrimal gland to produce tears?
CNVII
