11: Orbit, Eye, And Eye Movement Flashcards
Palpebral portion vs lacrimal portion of orbicularis oculi: function
Palpebral portion: gentle closing of eyelid
Lacrimal portion: tight closing of eyelid, dilates lacrimal sac
Levator palpebrae superioris O and I
O: lesser wing of sphenoid
I: tarsus / palpebral fascia and skin of upper lid
Levator palpebrae superioris N
CN 3
Tarsal muscle of muller O and I
O: lesser wing of sphenoid
I: tarsal plate of upper lid
Tarsal muscles innervation
Symp fibers from T1 (smooth muscles btw)
Horner’s syndrome
Paralysis of tarsal muscle, causing slight ptosis (also miosis, enophthalmos, anhydrosis, and bruising of skin on face
Location of lacrimal gland
Lacrimal fossa of orbit, with some protruding into the upper lid, otherwise on top of LR and LPS muscles
Lacrimal ducts
6-10 small ducts that drain into superior fornix
Path of tears draining from surface of eye
- Lacrimal canaliculi
- Common sinus
- Lacrimal sac
- Nasolacrimal duct
- Inferior meatus of nasal cavity
Lacrimal punctilious
Openings of the lacrimal canaliculi
MOI for blow-out fracture
Trauma to front of eyeball, depressed fracture of zygomatic which is displaced medially
What structures can be herniated in a blow out fracture, and where would they herniate into?
Periorbita, IO, IR, orbital fat pad -> into maxillary sinus
Which three nerves are used by both symp and parasymp nerves to innervate the lacrimal gland?
Maxillary N, lacrimal N, zygomatic N
Which type of nerve synapses in the sphenopalatine ganglion on the way to innervate the lacrimal gland, symp or parasymp?
Parasymp synapse there
Origin of all extraocular muscles besides inferior oblique
Annulus tendinius
Three major nerves to the orbit (all from V1)
Lacrimal N, frontal N, nasociliary N
Two branches of the lacrimal N
Zygomaticofacial, zygomaticotemporal N
Two branches of the frontal N
Supraorbital N, supratrochlear N
Three branches of the nasociliary N
Long ciliary N’s, posterior ethmoidal N, infratrochlear N
Main sensory N to the eyeball
Long ciliary N’s
Where is the ciliary ganglion?
Lateral to the optic nerve in the orbit
Three components of the triad of accommodation
- Convergence of gaze
- Pupillary constriction
- Thickening of lens
What muscles help with convergence of gaze
Medial recti
How does the lens thicken for near vision?
Ciliary zonule fibers relax, due to ciliary muscle contraction
Chief artery to the orbit
Ophthalmic A
Two terminal branches of the ophthalmic A
Supratrochlear A, dorsal nasal A
Two major branches of the ophthalmic A that supply the optic N
Posterior ciliary A, central retinal A
Chief blood supply to the retina
Central retinal A
Ciliary muscles
Circularly arranged smooth muscles around the lens
Where do nerves to the ciliary muscles come from?
Ciliary ganglion
Sphincter pupillae vs dilator pupillae muscles
Sphincter pupillae: circularly arranged for constricting pupil
Dilator pupillae: radially arranged for dilating pupil
Innervation to sphincter pupillae and dilator pupillae muscles
Sphincter pupillae: parasymp from ciliary ganglion
Dilator pupillae: symp from ciliary ganglion
Papilledema
Edema of the optic disc, causing extension of the subarachnoid space around the optic N
What causes papilledema
Increased intracranial pressure (is a medical emergency)
Hymphema
Presence of blood in anterior chamber
What causes hyphema
Trauma/rupture of greater arterial circle of the iris (medical emergency)
Subconjunctival hemorrhage
Bleeding in subconjunctival tissue
What causes subconjunctival hemorrhage
Rupture of deep pericorneal plexus
What causes conjunctivitis
Inflammation of superficial pericorneal plexus
Argyll-Roberson pupil
Pupils in reactive to light, but constrict during accommodation
What causes Argyll-Roberson pupil
Syphilis -> destruction of pretectum
Traumatic optic neuropathy
Ischemia of the intracanalicular portion of CN3
Hydrocephaly can cause..?
Compression of CN 6 in cavernous sinus
