The Orbit Flashcards
What bones are involved in the orbit
Frontal, zygomatic, maxilla, ethmoid, sphenoid and lacrimal
What is within the orbit
Eyeball, fat and connective tissue, extraocular muscles, nerves and blood vessels
What are the tarsal plates composed of
Dense connective tissue
What is the function of the tarsal plates
Support the eyelid and contain glands that secrete a watery fluid to lubricate the eyeball
What are the ligaments of the eye
Cheek and suspensory ligaments
Function of the suspensory ligament
Support the eyeball
Function of the cheek ligament
Restrict the movements of the medial and lateral recti
What is the eyeball composed of
Cornea, sclera, iris, ciliary body, choroid and retina
What makes up the fibrous outer coat of the eyeball
The cornea and sclera
What makes up the middle layer of the eyeball
The vascular layers
What is the retina composed of
Rods and cones
What does the retina make up
The inner coat
What is the blind spot within the retina
The optic disc
What is the macula lutea
The fovea of the retina
What makes the aqueous humor
Ciliary body
What is the function of the aqueous humor
Helps to maintain intra-ocular pressure
Where is aqueous humor drained into
The corneo-scleral junction by the canal of Schlemm
What is the vitreous humor
Embryological, transparent jelly, posterior to the lens that supports the retina
What is the function of the dilator pupilae muscles
Increases the diameter of the pupil
What innervates the dilator pupillae muscles
Sympathetic fibres
What does the sphincter pupilae muscle do
Decrease the diameter of the pupil
Innervation of the sphincter pupillae muscles
Parasympathetic fibres via the oculomotor nerve
What are int intrinsic eye muscles
Ciliary muscle
Function of the intrinsic muscles of the eye
Change the shape of the lens for accommodation
What innervates the intrinsic eye muscles
The oculomotor nerve
What are the 7 extraocular muscles
Levator palpabrae superioris, superior oblique, inferior oblique and the superior, inferior, medial and lateral recti
Where does the levator palpabrae superioris run from/to
The orbital roof to the upper eyelid
Where do the superior, inferior, medial and lateral recti run from/to
The annular ring to to the sclera, anterior to the equator
Where does the superior oblique run from/to
The lesser sphenoid wing to the sclera, posterior to the equator
Where does the inferior oblique run from/to
The orbital floor to the sclera, posterior to the equator
Why are the axes of orbit and optical axis different
So the eye muscles can move in more than one direction
What does the lacrimal apparatus produce
Tears
What innervates the lacrimal apparatus
Secretomotor fibres from the facial nerve
