Orbit And Cav Sinus - 1 Flashcards
What mm are non-functional in partial vs complete ptosis?
Partial: tarsal m
Complete: levator palpebrae superioris
Interruption of the pupil dilation pathway leads to what syndrome?
Horner’s syndrome d/t superior cervical ganglion lesion in cervical sympathetic trunk
What are the symptoms of Horner’s syndrome?
Ipsilateral pupillary constriction (miosis)
Slight ptosis
Anhydrosis/blushing d/t vasodilation in the face
Heterochromia
What is the accommodation pathway initiated for? What mediates this response? What is the “triad” response?
Near-sighted vision
Cerebral cortex
Triad: pupillary constriction via sphincter papillae mm, relaxation of ciliary zonule fibers by ciliary mm to round the lens for near-sighted vision, vision converges dT bilateral contraction of the medial rectus mm
Describe the findings regarding different Le Forte fractures.
Type 1: transverse fracture of maxillae
Type 2: pyramidal-shaped fractures of maxillae, also involves one orbit
Type 3: extensive transverse fracture of face, involves both orbits, face separated from base of skull
What does the ophthalmic a supply? What are its branches and what do they supply?
Chief a to the orbit
Posterior ciliary and central retinal, both supply the optic n
What does the central retinal a supply? What are its branches?
Main blood supply to the retina
Arterial circle of Zinn-Haller, upper and lower temporal branches, upper and lower nasal branches
What a supplies the upper eyelid and the lateral scalp?
Supraorbital a
What is the main a to the nose?
Anterior Ethmoidal a
What a supplies the medial portion of the scalp/forehead and the medial portion of the eyelids?
Supratrochlear a
What is Hyphema? What a is involved?
Presence of blood in the anterior chamber o the eyball dt trauma
Arterial circle of the iris
What is a sub-conjunctival hemorrhage? What blood supply is involved?
Rupture of the deep pericorneal plexus that causes bleeding around the inner eyelid
What is conjunctivitis/pink eye? What blood supply is involved?
Inflammation of the conjunctiva with redness that doesn’t fade when touched
Superficial corneal plexus involved
In regards to the lacrimal gland, what symp fiber is involved.. And from where? What parasymp fibers are involved.. And from where? Where do they go, and what do they become? Draw this out, too!
Symp: superior cervical ganglion –> deep petrosal n
Para: superior salivatory nucleus –> facial n –> greater sup. Petrosal n –> vidian n
These all go into the sphenopalatine ganglion, symp continues and parasymp synapses. Both groups leave as maxillary, zygomatic, and lacrimal branches.
What is the pathway of tear production and disposal?
Lacrimal gland –> 6-10 lacrimal ducts –> cornea –> lacrimal penctum –> lacrimal papilla –> lacrimal sac –> nasolacrimal duct which opens into the inferior concha
What is the clinical significance of the cavernous sinus?
Pituitary tumors here can compress structures located within the cavernous sinus, including: ICA, optic chiasm, CN: 3, 4, 5, and 6
What is anisocoria, and what causes it? What are the sx and when are they most apparent?
A difference in pupil size caused by lesions in the para or symp pathways to the eye
Abnormally large pupil size caused by lesion of the parasymp CN3 (cannot constrict) with ptosis, abnormally small pupil size caused by lesion of the symp CN2 (cannot dilate) with Horner’s
Abnormally large pupils are pronounced in the light because they don’t constrict. Abnormally small pupils are pronounced in the dark because they don’t dilate
What causes CN3 palsy, and what are the sx?
Aneurysm of the posterior communicating branch, herpes virus
Eye moves inferiorly and laterally (“down and out”) d/t CN3 innervating 4 of the 6 occular mm, pupil dilation, loss of levator papillae superioris function (ptosis)
What occurs when the listed nerves are injured: occulomotor (CN3), trochlear (CN4), abducens (CN6)
CN3: complete ptosis d/t no innervation to LPS, eye down and out
CN4: superior oblique doesn’t function, inability to adduct and depress the eye, pt tilts head away from affected eye
CN6: later rectus doesn’t function, inability to abduct the eye, double vision (diplopia)
What’s the innervation involved in the corneal reflex?
In by 5 (nasociliary), out by 7 (zygomatic branch)
With a “sundown gaze”, what is lesioned?
Abducens n
Increased intracranial pressure may put pressure on what cranial n?
Abducens which prevents one from abducting their eye
Intracranial pressure can decrease venous return from where causing what?
The retina, causing papilledema (swelling of the optic disk)
