Contents of the Orbit Flashcards
What part of the eye surrounds the pupil?
Iris
What layer covers the iris?
Cornea
Where do the eyelids meet?
Lateral/Medial CANTHUS
What shape is the orbit and where does it face?
Cone shaped
Directed anterolateral
Axis of orbit different than axis of eye
What structure holds the contents of the orbit?
Peri orbits
What runs through the Superior Orbital Fissure?
Where is it?
Ophthalmic Nerve (V1)
Oculomotor Nerve (III)
Trochlear Nerve (IV)
Abducens Nerve (VI)
Ophthalmic Vein
B/w greater and lesser sphenoid wings
What runs through the Optic Canal?
Where is it?
Optic Nerve
Ophthalmic Artery
Lesser Sphenoid Wing
What runs through the…
Inferior Orbital Fissure?
Zygomatic Foramen?
Ethmoid Canals?
IOF: Zygomatic Nerve (V2)
ZF: Zygomatic Nerve (V2)
EC: anterior and posterior ethmoid nerves (V1)
What are the muscles in the orbit?
Levator palpebrae
Superior rectus
Inferior recus
Medial rectus
Lateral rectus
Superior oblique
Inferior oblique
What connects the muscles of the eye?
What’s the exception?
Tendinous Ring - Annulus tendineous
EXCEPT inferior oblique, arises from anterior floor
Describe horizontal eye movement
Lateral Recuts = Abducts
Medial Rectus = Adducts
Simple movement
single muscle movements
Describe general vertical eye movement
very complex
Eyeball different orientation than the orbit
-> muscles from orbit pull eye in multiple directions
never one muscle alone
What is the movement of the Superior Oblique?
Depress
Abduct
Intort
What is the movement of the Inferior Oblique?
Elevate
Extorts
Abbduct
Attaches to lateral eye from below
What is movement of superior rectus?
Elevate
Intort
Adduct
What is movement of Inferior Rectus?
Depress
Extort
Adduct
What muscles do you use to look up? Down?
Upgaze:
- Superior Rectus
- Inferior Oblique
Downgaze:
Inferior Rectus
Superior Oblique
What happens when muscles don’t work together to cancel out?
Double vision
What’s the best way to test eye movement?
6 positions of gaze = H pattern
Adduct (MR)
- > elevate (IO)
- > depress (SO)
Abduct (LR)
- > elevate (SR)
- > depress (IR)
What elevates the eyelid?
Levator Palpebrae
-attaches to tarsal plate
Paralysis -> ptosis
(Superior tarsal muscle helps) - sympathetic
What is the sensory nerve of the orbit and it’s three major divisions?
Ophthalmic Division of Trigeminal (V1)
Frontal (superior)
Nasociliary (medial)
Lacrimal (lateral)
What does the frontal nerve supply?
2 branches
- Supra orbital =forehead
- Supratrochlear = medial eyebrow
What does nasociliary nerve do?
Parallels ophthalmic artery
3ish terminal branches
- Infratroclear (med can of eye)
- Anterior ethmoidal (into nasal cavity)
- Long ciliary (outer coverings and cornea)
Lacrimal nerve?
Lateral part of eyebrow
Are there parasympathetics in the eye?
Follow Oculomotor nerve
Ciliary ganglion and short ciliary
Constrict pupil
Contract ciliary muscle (changes lens)
How does the lens change focus?
FAR focus:
- ciliary muscles relaxed
- > intra ocular pressure pulls ligaments
- > lens flattened
NEAR focus:
- ciliary muscles contract
- > tension of suspense ligaments
- > lens rounded (relaxed)
What is the role of sympathetics in the eye?
DILATE pupil
Elevate eyelid
How is blood supplied to the eye?
Through OPHTHALMIC ARTERY
Central retinal artery follows optic nerve
Follows nasociliary nerve and branches similarly
Supraorbital branch meets up with so nerve
What should you note about the veins of the eye?
Infections can spread from sinuses, pharynx, orbit to the cavernous sinus
Very very bad
