Applied Anatomy and Physiology of the Eye Flashcards
From what structure does the central nervous system develop?
The neural tube.
At what week of gestation do the optic vesicles develop the eyes?
Between the 3rd and 10th week of gestation.
Name the three layers of the eye.
Outer fibrous coat, middle vascular layer, neurosensory layer.
What structures make up the outer fibrous coat of the eye?
Sclera and cornea.
What structures are part of the middle vascular layer of the eye?
Iris, ciliary body, choroid.
What are the components of the neurosensory layer?
Retinal pigment epithelium and neurosensory retina.
What is the volume of the eye globe?
7cc.
What is the axial length of the eye globe?
23-25 mm.
What are the components of the anterior chamber of the eye?
Aqueous humour, lens, vitreous body.
What are the accessory structures of the eye?
Eyebrows, eyelids, eyelashes, lacrimal apparatus, extraocular muscles.
What is the conjunctiva?
A transparent membrane overlying the eyeball and lining the eyelids.
What is the sclera?
The white of the eye, forming 5/6 of the outer coat.
What is the thickness of the sclera at the point where the optic nerve pierces it?
0.1 mm (at the lamina cribrosa).
What is the primary function of the sclera?
It helps maintain the shape of the eyeball and provides attachment for extraocular muscles.
What is the cornea and its function?
The transparent anterior 1/6 of the outer coat, responsible for refraction.
How much of the vision is provided by the cornea’s refractive surface?
70% of vision.
What is the dioptric power of the cornea?
+43D to +45D.
What is the iris, and what function does it serve?
A coloured diaphragm with a central aperture (the pupil); controls light entry.
What are the two groups of smooth muscle fibres in the iris?
Circular (sphincter pupillae) and radial (dilator pupillae) muscles.
What is the function of the ciliary muscle?
Accommodation (focus adjustment).
What is the main function of the ciliary processes?
Production of aqueous humour.
Where is the choroid located?
Between the sclera and retina.
What layers depend on the choroid for nutrition and blood supply?
The outer layers of the retina (up to the outer nuclear layer).
What is the retina, and how many layers does it have?
The neurosensory layer of the eye, composed of ten layers.
What is the function of the macula?
Sharp, detailed vision.
What is the location and function of the optic disc?
Located nasally, it aggregates nerve fibres (optic nerve) and is 1.5 mm in diameter.
What is the volume and composition of aqueous humour in the eye chambers?
0.25 ml in the anterior chamber and 0.06 ml in the posterior chamber; aqueous humour is similar to plasma but has higher concentrations of ascorbate, pyruvate, and lactate.
How is aqueous humour produced?
Produced by the non-pigmented ciliary epithelium, at 2-3 µl/min.
What is the normal intraocular pressure range?
10-21 mmHg (by applanation).
What is the function of the crystalline lens?
A biconvex, transparent structure that focuses light.
What is the volume of the vitreous humour in the eye?
4-4.5 ml of transparent gel.
Name the extraocular muscles responsible for the movement of the eyeball.
Medial rectus, lateral rectus, superior rectus, inferior rectus, superior oblique, inferior oblique.
What is the primary artery supplying blood to the eye?
Ophthalmic artery (branch of internal carotid artery).
What veins are involved in the venous drainage of the eye?
Short and anterior ciliary veins, vortex veins, central retinal vein.
Name the motor nerves that supply the eye.
Oculomotor (3rd CN), trochlear (4th CN), abducens (6th CN), facial (7th CN).
What sensory nerve supplies the whole eye?
Trigeminal nerve – ophthalmic branch.
What are the autonomic nerves that supply the eye?
Sympathetic: iris (dilator pupillae), ciliary body, lacrimal gland; parasympathetic: iris (sphincter pupillae), ciliary body, lacrimal gland.
Name the bones that make up the bony orbit of the eye.
Ethmoid, sphenoid, maxilla, frontal, palatine, lacrimal, zygoma.
What forms the roof of the orbit?
Orbital plate of the frontal bone and lesser wing of the sphenoid.
What forms the medial wall of the orbit?
Orbital plate of ethmoid, maxilla, lacrimal, and body of the sphenoid.
