Ophthamology Flashcards
(102 cards)
What 6 bones is the orbit made up of?
Frontal Zygomatic Maxillary Sphenoid Ethmoid Lacrimal
What bones have orbital plates? Why is this relevant?
The frontal bone, maxillary and ethmoid have orbital plates which are flatter they are thin walled and therefore fracture easily
The optic canal is located _____1_____ for passage of ________2__________
1) posteromedially
2) optic nerve and ophthalamic artery
Superior orbital fissure is formed by? What nerves are found going through this?
the gap between the greater and lesser wings of the sphenoid bone
cranial nerves responsible for the movement of the eye are found coming through here (3,4 and 6)
and CNV1
The shape of the orbit is described as being a _______
What is the apex and the base?
pyramid
Apex is at the optic canal and base is anterolaterally
Base is a combination of medial, lateral, superior and inferior margins
Why is the eye well protected?
Eye is very well protected due to superior margin overhanging inferior and the bones that surround are quite tough
Describe a blow-out fracture of the orbit? What is a complication?
There is a fracture of one of the walls of orbit but the orbital rim remains intact. This is typically caused by a direct blow to the central orbit from a fist or ball. If impact around the bony orbit is strong enough pressure can be transferred to the thinner bones and will get fracture of the thinner bones.
Trap door fracture, fracture of the orbital floor where the inferiorly displaced blowout fracture recoils back to its original position and potentially entraps contents of the orbit.
What is the most external part of the eyelid? What is the function?
Orbicularis oculi muscle which is responsible for closing the eyelids
Describe what is in the deeper layer of the eyelid?
Superior and inferior tarsus
Orbital septum
Palpebral ligaments
Describe the orbital septum and its function?
The orbital septum is a thin, fibrous membrane that serves as a barrier between the superficial lids and the orbit.
Describe the tarsus of the eyelids and their function?
There are two plates; the superior tarsus (upper eyelid) and inferior tarsus (lower eyelid). They act to form the scaffolding of the eyelid, and are composed of dense connective tissue. The superior tarsus also acts as the attachment site of the levator palpebrae superioris.
The lacrimal gland produces lacrimal fluid and has parasympathetic innervation originating from branches of?
Facial nerve- CN7
Greater petrosal nerve
Lacrimal gland is located _____1____ in the orbit. Fluid washes over eye and is pushed in a ___2__ angle and drains through ____3______ into ___4____ and then into ____5_____ duct eventually into _____6________
1) superolaterally (just below eyebrow)
2) medial
3) lacrimal punta (small opening- dot on eyelid)
4) lacrimal sac
5) nasolacrimal
6) inferior nasal meatus
How many extra ocular muscles are there? What are they?
Seven
4 rectus muscles: superior, inferior medial and lateral rectus muscles
2 oblique muscles: superior oblique and inferior oblique
1 levator palpebrae superioris
All extra ocular muscles apart from _____ insert onto the sclera
Levator Palpebrae Superioris which inserts onto the skin and tarsus of superior eyelid
All rectus muscles originate from _______ and insert onto ______
common tendinous ring
Sclera
The superior oblique muscle originates from ___1__ and inserts onto ____2_____
1) sphenoid bone
2) sclera
The inferior oblique muscle originates from ___1__ and inserts onto ____2_____
1) orbital plate of maxilla
2) sclera
The levator palpebrae superioris muscle originates from ___1__ and inserts onto ____2_____
1) lesser wing of sphenoid
2) skin and tarsus of superior eyelid
Describe the trochlea in the orbit?
The trochlea of superior oblique is a pulley-like structure in the eye. The tendon of the superior oblique muscle passes through it. Situated on the superior nasal aspect of the frontal bone, it is the only cartilage found in the normal orbit.
NOTE THAT THE TROCHLEAR NERVE ONLY INNERVATES SUPERIOR OBLIQUE WHICH HAS A TROCHLEA!
Describe the innervation of the extraocular muscles?
Lateral Rectus= CN6 - the abducent nerve because it ABDUCTS the eye
Superior Oblique= CN4- the trochlea nerve because it HAS A TROCHLEA
All others= CN3- oculomotor - CLUE IN THE NAME
LR6 SO4 AO3 (apparently it’s catchy?)
What is the lacrimal lake?
pool of tears in the lower conjunctival cul-de-sac, which drains into the opening of the tear drainage system
What is the lacrimal papilla and punctum?
In medical terms, the lacrimal papilla is a small conical elevation on the margin of each eyelid at the basal angles of the lacrimal lake. Its apex is pierced by a small orifice, the lacrimal punctum where fluid drains into the lacrimal sac.
What is the iris?
coloured part of the eye that controls the size of the pupil in the middle