Eye Anatomy and Physiology Flashcards
What muscle supplies movement of upper eyelid?
Levator palpebrae superioris muscle
What is the gap between upper and lower eyelids called?
Palpebral fissure
From superficial to deep what are the layers of the eyelid?
Epidermis
Dermis
Subcutaenous tissue
Obicularis oculi muscle
Tarsal plate
Tarsal glands
Conjunctiva
What keeps the eyelids from sticking together?
Infection of said structure is called what?
Sebaceous fluid produced by the tarsal gland
Chalazion
What structure covers the inner aspect of the eyelids?
Palpebral conjunctiva
What structure covers the sclera from the eyelids?
Bulbar conjunctiva - it is vascular. Irritation of this is the cause of bloodshot eyes
Infection of the sebaceous ciliary glands of the eyelashes can lead to what?
A stye
- Which extraocular muscle does eye abduction?
- Which muscle does eye adduction?
- Which muscle moves eye upwards?
- Which muscle moves eye downwards?
- Which muscle moves eye up and out?
- Which muscle moves eye down and out?
- Lateral rectus
- Medial rectus
- Superior rectus
- Inferior rectus
- Superior oblique
- Inferior oblique
What is the coloured part of the eye called?
Whats the function?
iris
To regulate the amount of light entering eyeball via the pupil
What two types of muscles does the iris contain?
What else does the iris contain?
Circular muscle
Radial muscle
Melanocytes
What determines eye colour?
Iris melanocyte conc high = brown eyes
Melanocyte conc moderate = green eyes
Melanocyte conc low = blue eyes
Why is the pupil black?
Because you are visualising the heavily pigmented retina and choroid through the pupil and lens
The Parasympathetic NS causes the pupil to what? Which muscle causes this?
The Sympathetic NS causes the pupil to what?
Constrict; circular muscle of iris
Dilate; radial muscle of iris
What covers the eyeball except the cornea, gives the eyeball shape, protects the eye’s inner parts and serves as an attachment for the extraocular muscles?
Sclera - dense connective tissue
What is the transparent curved part of the eye that covers the iris?
Cornea
What are the 3 outer layers of the eyeball wall (superficial to deep)
Sclera (superficial)
Choroid
Retina (deep)
What is the structure that is…
Attached to the inner surface of sclera, provides blood vessels to the retina, and has melanocytes to absorb stray light rays to avoid glare in the eyeball?
Choroid
Why do albinos need to wear sunglasses or have trouble seeing?
Their choroid lacks melanin, so less stray light is absorbed in the choroid meaning they experience lots of glare in normal light
What are the three layers of the eyeball?
- Fibrous tunic - anterior cornea, posterior sclera
- Vascular tunic (aka uvea)- iris, ciliary body, choroid
- Retina (inner tunic)
In the anterior portion of the vascular tunic the choroid becomes the…
Ciliary body
Ciliary body is where ___ is formed
Ciliary body is where aqueous humour is formed
Which cranial nerves supply which of the extraocular muscles?
CN III (superior/inferior/medial rectus, inferior oblique)
CN IV (superior oblique)
CN VI (lateral rectus)
What is the structure that is the innermost layer of the eyeball, and is the beginning of the visual pathway?
Retina
How does the lens adapt to near and far vision?
Lens is attached to cilliary muscles which contract or relax, altering the shape of the lens to adjust to near/far vision
The optic (CN II) nerve exits the eyeball at the…
Optic disc
What 3 structures pass through the optic disc?
CN II
Central retinal artery
Central retinal vein
The 2 layers of the retina and their functions are…
Pigmented disc - deeper layer, contains melanin to absorb stray light rays to reduce glare
Neural disc - more superficial, contains photoreceptors to process visual data -> sends nerve impulses across axons of CN II
2 types of photoreceptors are called…
Rods (120 million)
Cones (6 million)
Function of rods and cones?
Rods - stimulated by dim light, do not process colour vision (therefore can only see in black/grey/white in the dark)
Cones - stimulated by bright light, produce colour vision, 3 types of cones (blue, green and red depending on which colour of light they process)
Loss of cones function can lead to…
Legal blindness
What is the blind spot, and why is it called a blind spot?
Optic disc is the blind spot as it contains no photoreceptors
Therefore cannot see any images that strike the blind spot
The centre of the posterior portion of the retina is called the…
Macula
The central depression of the macula, which contains only cones is called the..
Why is this structure significant?
Fovea
It is the area of highest visual acuity (Reason why you move your eyes to see something, in order to make the image land non the fovea)
The structure that helps focus images on the retina is called…
Lens
The lens divides the inside of the eyeball into what 2 areas?
Anterior cavity (consists of anterior chamber and posterior chamber)
Vitreous chamber
- Anterior chamber is between what two structures?
- Posterior chamber is between what two structures?
- Between cornea and the iris
- Behind the iris and in front of lens
What is the name of the fluid that is in the anterior cavity, nourishes the lens + cornea and is continually flowing?
Aqueous humour
Describe the path of flow of aqueous humour?
Secreted out of ciliary body
Enters posterior chamber
Flows through pupil into anterior chamber
Drains into trabecular meshwork and into canal of Schlemm
Goes into blood
The fluid inside the vitreous chamber that holds the retina flush against the choroid, and removes debris is called…
Vitreous body
Debris in the vitreous body that casts shadows over the retina create…
Floaters
Intraocular pressure is mainly formed by…
Aqueous humour (and vitreous body to a lesser extent)
Normal IOP is what?
16mmHg
