5.1 Anatomy of the Orbit, Orbital Region and Eyeball Flashcards
Which 6 bones make up the orbit?
Frontal Sphenoid Ethmoid Lacrimal Maxilla Zygomatic
Name the 4 openings in the orbital cavity
Optic canal
Superior orbital fissure
Inferior orbital fissure
Nasolacrimal canal
What structures lie in the optic canal?
Optic nerve and optic artery
What structures lie in the superior orbital fissure?
Lacrimal nerve Frontal nerve Trochlear nerve Oculomotor nerve Nasociliary nerve Abducens nerve
Superior ophthalmic vein
What structures lie in the inferior orbital fissure?
Maxillary nerve
Inferior ophthalmic vein
Sympathetic nerves
What is the purpose of the nasolacrimal canal?
Drains tears to nasal cavity
Which bone are the optic canal, superior and inferior orbital fissure located in?
Sphenoid bone
What is an orbital rim fracture?
Fracture of the bones forming the outer rim of the bony orbit ie. Maxilla, zygomatic and frontal bones
What is a blowout fracture?
Contents of the orbit partially herniate into the maxillary sinus. Patient cannot look up as inferior rectus muscle is trapped
What is exophthalmos?
Protrusion of the eye due to increased intraocular pressure
What makes up the outer fibrous layer of the eyeball?
Sclera and cornea
What makes up the middle vascular layer of the eyeball?
Choroid, iris and ciliary body
What makes up the inner layer of the eyeball?
Retina
What is retinal detachment?
The retina becomes free of the choroid so loses its blood supply and undergoes necrosis
Where is fluid produced in the eye?
Ciliary bodies
Where does fluid in the eye drain to?
Trabecular meshwork
What is open angle glaucoma?
Trabecular meshwork of eye becomes blocked so there is an accumulation of fluid in the aqueous humour. Increased pressure in the eye results in damage to the optic nerve and a loss of vision
What are cataracts?
Lens of the eye becomes harder and flattened
Name the 6 muscles around the eyeball and in what direction they move it
Superior rectus- look superiorly Medial rectus- look medially Inferior rectus- look inferiorly Lateral rectus- look laterally Superior oblique- rotate down Inferior oblique- rotate up
What nerve supplies the lateral rectus muscle?
Abducens nerve
What nerve supplies the superior, medial and inferior rectus muscles?
Oculomotor nerve
What nerve supplies the inferior oblique muscle?
Oculomotor nerve
What nerve supplies the superior oblique muscle?
Trochlear nerve
How can the superior oblique muscle be tested?
Look medially and down.
Problem: patient won’t be able to look down
How can the inferior oblique muscle be tested?
Patient will not be able to look medially and upwards
What are the origins of the ophthalmic artery?
Branch of the internal carotid artery
What happens if there is an occlusion of the ophthalmic artery?
Retina turns pale as the branches of the ophthalmic artery are end arteries
Where does the blood supply of the eye drain to?
Central retinal vein –> Superior ophthalmic vein –> Cavernous sinus
What does central retinal vein occlusion cause?
Blurry vision when dehydrated and pressure on the optic disk.
What is the function of the lacrimal gland?
Produces fluid which is swept over the eye
What is the function of the eyelid?
Protects against injury, dryness and excessive light
What area of the eye does the bulbar conjunctiva cover?
Sclera of the eye
What area of the eye does the palpebral conjunctiva cover?
Inner lining of eye socket
What is conjunctivitis?
Inflammation of the bulbar conjunctiva
What is the difference between tarsal gland inflammation and ciliary gland inflammation?
Tarsal gland inflammation is painless swelling of the eyelid. Ciliary gland inflammation is more serious and needs antibiotics to treat
What muscle opens the eye?
Levator palpebrae superioris
What nerve innervates the levator palpebrae superioris?
CN III (Oculomotor)
What muscle closes the eye?
Orbicularis oculi
What nerve innervates the orbicularis oculi?
CN VII (Facial)
