Anatomy of the eye Flashcards
Name the labelled structures.
Clockwise from top right corner:
Orbital plate of the ethmoid bone
Nasal bone
Lacrimal bone
Maxilla
Zygoma
Superior orbital fissure (of sphenoid bone)
Sphenoid bone
Optic canal
Orbital plate of the frontal bone
Supraorbital notch/foramen
Which bones/walls of the orbit are most vulnerable to damage in an orbital blowout fracture?
Medial wall- orbital wall of ethmoid bone
Floor- maxilla
Which muscle acts as the “sphincter” of the eye?
Orbicularis oculi
Which muscle raises the upper eyelid?
Levator palpabrae superioris
What is the role of the orbital septum?
Prevents the spread of infection from the peri-orbit (superficial) to the orbit (deep)
Name the labelled structures.
From top centre:
Iris (covered by avascular cornea)
Lacrimal lake
Inferior lacrimal papilla and punctum
Lower eyelid lined by conjunctiva
The conjuctival fornix (where conjunctiva reflects off the sclera onto the internal aspect of the eyelid)
White sclera covered by conjunctiva
Limbus
Location of the lacrimal gland
Which nerve supplies the lacrimal gland?
Facial nerve
Where does the nasolacrimal duct open into?
The inferior meatus of the nasal cavity
What are the three layers of the eye?
Fibrous (cornea and sclera)
Uvea (vascular)
Retina (photosensitive)
In the anterior segment, what are the roles of:
a) the iris
b) the lens
c) the ciliary body
a) controls pupil diameter
b) further refraction of light
c) controls the refractive shape of the lens and secretes aqeous humour
What are the three chambers of the eye?
Anterior, posterior and vitreous body
What are the contents of the anterior segment?
From anterior to posterior:
Cornea; anterior chamber; iris; lens; ciliary body; posterior chamber
What are the contents of the posterior segment?
Vitreous body; 2/3rds of sclera; choroid; retina
What is the path taken by aqeous?
Secreted by ciliary body; moves into the posterior chamber nourishing the lens; circulates past the lens into the anterior chamber nourishing the cornea; is reabsorbed into the scleral venous sinus at the iridocorneal angle
What is the fovea centralis?
Area of most acute vision; area of the retina with highest concentration of cones
What is the opthalmic artery a branch of?
The internal carotid artery
What is an “end artery”? How does this relate to the eye?
An artery with insufficient anastamoses to maintain viability of the tissue supplied should an occlusion occur.
The central artery of the eye (first branch of the opthalmic artery) is an end artery
Which vein drains the retina?
The central vein of the retina
Where do the superior and inferior opthalmic veins drain to?
The cavernous sinus (inferior drains into superior initially)
What does the blind spot of the visual field correspond to?
The optic disk
How is vision affected by an obstruction in
a) a retinal artery branch or “branch” retinal vein
b) central artery or vein
a) visual loss corresponding to the area of ischaemia
b) complete monocular visual loss
What are the three layers of the retina from posterior to anterior?
Photoreceptor cells; ganglia of photoreceptors; axons of photoreceptors
Where are the visual cortices?
The right and left temporal lobes
Where is light from the right visual field processed?
The left visual cortex
How are spatial relationships in the visual pathways preserved?
Axons maintain specific spatial (both horizontal and vertical) relationships to each other
Name the seven extraorbital skeletal muscles.
Four rectus (superior, inferior,medial, lateral)
Two oblique (superior and inferior)
Levator palpebrae superioris
What does LR6 S04 AO3 mean?
Lateral rectus- abducens
Superior oblique- trochlear
All others- oculomotor
