Eye Flashcards
What shape can the orbit of the eye be thought as
Pyramidal
What are the boundaries of the bony orbit
Roof
Floor
Medial wall
Lateral wall
Apex
Base
What is the roof of the orbit made from
Frontal bone and lesser wing of sphenoid
What is the floor of the orbit made from
Maxilla, palatine, zygomatic bones
What is the medial wall of the orbit compromised of
Ethmoid, maxilla, lacrimal and sphenoid bones
What is the lateral wall of the orbit compromised of
Zygomatic bone and greater wing of the sphenoid
What is the apex of the orbit compromised of
Located at the opening of the optic canal - the optic foramen
What is the base of the orbit compromised of
Opens out into the face
Bounded by the eyelids
Also known as the orbital rim
What separates the orbit from the ethmoid sinus
Ethmoid bone
What separates the orbit from the underlying maxillary sinus
Maxilla
What does the frontal bone separate the orbit from
Anterior cranial fossa
What are the contents of the orbit
Extra-occular muscles
Eyelids - cover orbit anteriorly
Nerves
Blood vessels
What is the primary blood supply to the eye
Ophthalmic artery
What is venous drainage to the eye
Superior and inferior ophthalmic veins
What is the space in the orbit filled with
Orbital fat - act as a cushion
What are the three main pathways structures ca n leave and enter the orbit
Optic canal
Superior orbital fissure
Inferior orbital fissure
What parts can the eyeball be divided into
Fibrous
Vascular
Inner layers
Describe the fibrous layer of the eye
Outermost layer
Consists of sclera and cornea
What are the main functions of the cornea and sclera
Provide shape to the eye and support the deeper structures
Describe the sclera
Approx. 85% of fibrous layer
Provides attachment for extraocular muscles
Describe the cornea
Transparent and positioned centrally at the front of the eye
Light entering the eye is refracted by the cornea
Describe the vascular layer
Consists of choroid, ciliary body and iris
Describe the choroid
Layer of connective tissue
Provides nourishment to the outer layers of the retina
Describe the ciliary body
Two parts - ciliary muscle and ciliary processes
Ciliary muscle - collection of smooth muscle fibres.
Attached to lens of the eye by the ciliary processes.
Ciliary body controls the shape of the lens, contributes to the formation of aqueous humor
Describe the iris
Circular structure - aperture in the centre (the pupil)
Diameter of the pupil is altered by smooth muscle fibres within the iris
Describe the inner layer of the eye
Formed by the retina = light detecting component
- pigmented (outer layer) - formed by a single layer of cells
- Neural (inner) layer) - consists of photoreceptors, light detecting cells of the retina
What is the centre of the retina marked by an area known as…
Macula - yellowish in colour and highly pigmented
What is the depression in the macula
Fovea centralis - has a high concentration of light detecting cells
Describe the vitreous body
Transparent gel which fills the posterior segment of the eyeball
Three main functions
- contributes to the magnifying power of the eye
- support the lens
- holds the layers of the retina in place
What is the narrow canal which runs from the optic disc to the lens
Hyaloid canal
What alters the lens shape
Ciliary body
