Eye Flashcards
What forms the outer eye?
Cornea and sclera
What is the function of the cornea?
Transmission and refraction of light
What is the function of the sclera?
- Forms white capsule of collagen around eye to offer protection.
- Serves as an insertion point for the external muscles of the eye
What forms the middle eye?
Iris, ciliary body, choroid
What is the function of the iris?
Controls size of pupil to let in varying amounts of light.
Which muscles are involved in controlling the size of the pupil?
1. Sphincter muscles They have circular fibres. They make the pupil smaller (parasympathetic) 2. Dilator muscles They have radial fibres They make the pupil larger (sympathetic)
What is the function of the ciliary body?
- Has glandular epithelium to produce aqueous humour & nutrients for the cornea
- Made of smooth muscle to control accommodation of lens
What innervation does the ciliary body receive?
Parasympathetic
What is the function of the choroid?
- Darkly pigmented to absorb stray protons.
- Important for nutrition of outer retina.
- Acts as heat sink.
What forms the inner eye?
Retina
What is the function of the retina?
Receives light from lens and converts this to neural signals. Produces vitreous humour which helps transmits light.
At what points is the retina specialised for maximal resolving power?
Fovea centralis and macula lutea.
What is the blind spot?
The optic disc. Photoreceptors are absent here.
What epithelium is found in the retina?
Retinal pigment epithelium
Name two photoreceptors and their functions.
- Rods: Vision in dim lighting; peripheral vision
2. Cones: colour vision
Give the three layers of the tear film.
Anterior = lipid. Prevents aqueous layer from evaporating. Middle = aqueous. Prevents infection. Posterior = mucous. Allows for even distribution of tear film.
Briefly give the layers through which a photon must travel through the eye.
- Tear film
- Cornea (refraction also)
- Aqueous humour
- Lens
- Vitreous humour
- Ganglion cell
- Amacrine cell
- Bipolar cell
- Horizontal cell
- Cone
- Rods
- Pigmented epithelium
Which arteries supply the eye?
Internal carotid artery > Opthalmic artery > Central retinal artery > Ciliary arteries > Lacrimal artery > Ethmoid & Eyelid artery
External carotid artery > Facial artery
Where is the primary visual cortex located?
Medial surface of occipital lobe, above and below calcarine sulcus.
What is the function of the visual association cortex?
Interpretation of visual images, recognition, depth perception and colour vision.
What happens if there is damage to the left optic nerve?
No vision through left eye.
What happens if there is damage to the optic chiasma?
Hemianopia = Loss of vision of the temporal visual fields.
What happens if there is damage to the left optic tract?
Loss of vision of temporal field of left eye & loss of nasal field of right eye.
What happens if there is damage to left Meyer’s loop?
Loss of vision in superior nasal field of left eye and superior temporal field of right eye.
What happens if there is damage to Baum’s loop?
Loss of vision in inferior temporal field of right eye and inferior nasal field of left eye.
Name the 6 ocular eye muscles.
Medial rectus Lateral rectus Superior oblique Inferior oblique Superior rectus Inferior rectus
Which muscles does CN III innervate?
Medial rectus, inferior oblique, superior rectus, inferior rectus.
Where is the nuclei of CN III and CN IV located?
Periaqueductal grey near cerebral aqueduct.
Which muscle does CN VI innervate?
Lateral rectus
Which muscle does CN IV innervate?
Superior oblique
