Anatomy of the Eye Flashcards
Where does the optic nerve lie ?
Posterior aspect of the eyeball
Name the three layers of the eyeball?
Fibrous, vascular and sensory
The cornea and sclera lie within which layer?
Fibrous layer
The iris, ciliary body and the choroid lie within which layer?
The vascular layer
The retina is made up of how many layers?
10
What is the function of the choroid?
To supply blood to the outer layers of the retina
What is the function of the cornea?
To allow light rays to enter the eye
Where does the iris hang from?
The ciliary body
What is the function of the ciliary body?
To suspend the lens and produce aqueous humour. It also contains muscles which can change the shape of the lens
What is the function of the iris?
To control the diameter of the pupil
What do concentric and radial muscles of the iris do?
Control the amount of light rays which can enter the eye
What is the lens suspended by?
Suspensory ligaments
What does the anterior segment of the eyeball contain?
Aqueous humour
What is the function of Aqueous humour?
To assist in the maintenance of intraocular pressure
What does the anterior segment of the eyeball split into?
The anterior chamber (in front of iris) and posterior chamber (behind iris)
Why is a corneal transplant easier than a typical organ transplant?
Cornea is avascular so there is lesser chance of graft rejection
What is the function of the epithelium of the retina?
To maintain the health of rods and cones
Where is the site of most visual activity?
The fovea centralis
What kind of epithelium forms the outer layer of the cornea?
Stratified, non-keratinised squamous epithelium
If the epithelium of the cornea is scratched, what would be the best treatment?
Topical treatment applied to eye
What is the result of an injury which penetrates the Bowman’s membrane?
A corneal scar
What occurs if the endothelium layer is damaged?
Endothelial cells enlarge to compensate until they are lost. The AH pump will then not work as efficiently as it should as AH will enter the cornea and it becomes opaque = light has trouble getting through.
Describe the passage of Aqueous Humour from the Angle of the Anterior Chamber to the Episcleral Veins
Ant. Angle of chamber –> trabecular mesh-work –> schlemm’s canal –> episcleral veins
What is lens opacification also known as?
Cataracts
What are the functions of the tear film?
Keeps cornea moist, washes away foreign bodies, has antimicrobial properties in the form of lysozymes to kill microbes, smooths over outer surface of the cornea to provide a smooth surface for refraction
What cranial nerve innervates the tear film?
The facial nerve (CNVII)
What nerve innervates the ciliary muscles?
The occularmotor nerve (CNIII)
Why is the medial recti thicker than the lateral recti in humans?
As humans often look at things up close
What is the function of the intrinsic muscles of the eye?
Control pupil diameter and helps alter lens curvature to enable us to see near objects
What is the function of the extrinsic muscles?
To move the eye
Name the four rectus muscles in the eye?
Medial rectus, lateral rectus, inferior rectus and superior rectus
Name the two oblique muscles of the eye?
Superior Oblique and Inferior Oblique
What is the superior oblique innervated by?
CNIV
What is the Lateral Rectus innervated by?
CNVI
What axis are the muscles of the eye attached to?
The orbital axis
When LR has abducted the eye, SR causes…?
Elevation
When LR has abducted the eye, which muscle causes depression?
IR
When the MR has adducted the eye, what muscle causes intorsion?
SR
When MR has adducted the eye, IR causes…?
Extorsion
What lies within the opic foramen?
The optic nerve and he opthalmic artery
What nerve lies within the inferior orbital fissure?
The maxillary division of the trigeminal nerve
What muscle is responsible for accomodation?
The ciliaris
What bones make up the orbit ?
Sphenoid, Ethmoid, Maxilla, Zygomatic, Frontal Palatine and the Lacrimal bone
What passes through the optic foramen?
Optic Nerve, Opthalmic Artery
What passes through the superior orbital fissure?
CNIII, IV Nerve, Abducent Nerve, Opthalmic Division of V nerve, Opthalmic Veins and Lacrimal Nerve
What passes through the inferior orbital fissure?
Maxillary division of V nerve
What divides the eyeball into the anterior and posterior segment?
The crystalline lens
What is the action of the MR?
Adduction
What is the function of the LR?
Abduction
What is the function of the SR?
Elevation, Adduction and Intorsion
What is the function of the IR ?
Depression, Adduction and Extorsion
What is the function of the SO?
Depression, Abduction and Intorsion
What is the function of the IO?
Extorsion, Elevation and Abduction
Which is the only muscle which does not arise from the posterior aspect of the eye?
IO
Which ligaments prevent over adduction/abduction?
The medial and lateral ligaments