Orbit And Cav Sinus - 1

Question 1

What mm are non-functional in partial vs complete ptosis?

Answer 1

Partial: tarsal m
Complete: levator palpebrae superioris

Question 2

Interruption of the pupil dilation pathway leads to what syndrome?

Answer 2

Horner’s syndrome d/t superior cervical ganglion lesion in cervical sympathetic trunk

Question 3

What are the symptoms of Horner’s syndrome?

Answer 3

Ipsilateral pupillary constriction (miosis)
Slight ptosis
Anhydrosis/blushing d/t vasodilation in the face
Heterochromia

Question 4

What is the accommodation pathway initiated for? What mediates this response? What is the “triad” response?

Answer 4

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

Question 5

Describe the findings regarding different Le Forte fractures.

Answer 5

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

Question 6

What does the ophthalmic a supply? What are its branches and what do they supply?

Answer 6

Chief a to the orbit

Posterior ciliary and central retinal, both supply the optic n

Question 7

What does the central retinal a supply? What are its branches?

Answer 7

Main blood supply to the retina

Arterial circle of Zinn-Haller, upper and lower temporal branches, upper and lower nasal branches

Question 8

What a supplies the upper eyelid and the lateral scalp?

Answer 8

Supraorbital a

Question 9

What is the main a to the nose?

Answer 9

Anterior Ethmoidal a

Question 10

What a supplies the medial portion of the scalp/forehead and the medial portion of the eyelids?

Answer 10

Supratrochlear a

Question 11

What is Hyphema? What a is involved?

Answer 11

Presence of blood in the anterior chamber o the eyball dt trauma

Arterial circle of the iris

Question 12

What is a sub-conjunctival hemorrhage? What blood supply is involved?

Answer 12

Rupture of the deep pericorneal plexus that causes bleeding around the inner eyelid

Question 13

What is conjunctivitis/pink eye? What blood supply is involved?

Answer 13

Inflammation of the conjunctiva with redness that doesn’t fade when touched

Superficial corneal plexus involved

Question 14

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!

Answer 14

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.

Question 15

What is the pathway of tear production and disposal?

Answer 15

Lacrimal gland –> 6-10 lacrimal ducts –> cornea –> lacrimal penctum –> lacrimal papilla –> lacrimal sac –> nasolacrimal duct which opens into the inferior concha

Question 16

What is the clinical significance of the cavernous sinus?

Answer 16

Pituitary tumors here can compress structures located within the cavernous sinus, including: ICA, optic chiasm, CN: 3, 4, 5, and 6

Question 17

What is anisocoria, and what causes it? What are the sx and when are they most apparent?

Answer 17

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

Question 18

What causes CN3 palsy, and what are the sx?

Answer 18

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)

Question 19

What occurs when the listed nerves are injured: occulomotor (CN3), trochlear (CN4), abducens (CN6)

Answer 19

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)

Question 20

What’s the innervation involved in the corneal reflex?

Answer 20

In by 5 (nasociliary), out by 7 (zygomatic branch)

Question 21

With a “sundown gaze”, what is lesioned?

Answer 21

Abducens n

Question 22

Increased intracranial pressure may put pressure on what cranial n?

Answer 22

Abducens which prevents one from abducting their eye

Question 23

Intracranial pressure can decrease venous return from where causing what?

Answer 23

The retina, causing papilledema (swelling of the optic disk)