Orbit DR

Question 1

What structure passes through the notch in the frontal bone?

Answer 1

Supraorbital nerve

Question 2

What are the branches of the trigeminal nerve

Answer 2

opthalmic, max, mandibular

Question 3

What are the branches of the frontal nerve?

Answer 3

supraorbital and supratrochlear nerves

Question 4

what is the function of the supraorbital nerve?

Answer 4

sensory supply to forehead, upper eyelid and anterior scalp

Question 5

supratrochlear nerve function

Answer 5

sensory supply to inferomedial forehead, bridge of nose and medial part of inferior eyelid

Question 6

branches of V1 opthalmic

Answer 6

frontal nerve
lacrimal nerve
nasociliary nerve

Question 7

What does the nasociliary nerve supply?

Answer 7

ethmoid sinus
skin over the nose
structures of the eye itself
The nasociliary nerve carries pain and touch sensation from the cornea via its long posterior ciliary branches.

Question 8

What are the branches of the nasociliary nerve?

Answer 8

long posterior ciliary nerve
short ciliary nerve
anterior and posterior ethmoidal nerves

Question 9

what is a blowout fracture?

Answer 9

occur when there is a fracture of one of the walls of orbit but the orbital rim remains intact. Because the medial and inferior walls of the orbit are thin trauma to
the orbit can cause these walls to fracture whilst the orbital margin remains intact
Orbital blowout fractures classically present with posterior displacement of the globe (eyeball),
diplopia (double vision), ophthalmoplegia (incorrect eye movements) and hypoaesthesia (reduced
sensation) in the mandibular nerve distribution

Question 10

What problems can an orbital fracture cause?

Answer 10

Some cases of orbital trauma can result in bleeding into the retrobulbar space (the potential space behind the globe between the extra-ocular muscles)/ This causes intraorbital pressure to increase causing reduced perfusion to eyeball and optic nerve resulting in potential loss of vision

Question 11

What treatment might be done for orbital fracture with increased pressure?

Answer 11

Emergency lateral canthotomy can be performed to allow anterior migration of the eyeball and
subsequent reduction in pressure.

Question 12

what is the nerve supply to the extraocular muscles?

Answer 12

CN3 oculomotor nerve - levator palpebrae, inf oblique, sup medial and inf recti muscles

CN4 trochlear - superior oblique

CN6 abducens - lateral rectus

Question 13

What is oculomotor nerve palsy?

Answer 13

damage to the oculomotor nerve can result in a “Down and out” pupil. A lateral gaze occurs as the oculomotor nerve inntervates the medial rectus whereas the lateral rectus muscle is innervated by the abducens nerve (CN 6). Paralysis of medial rectus (CN 3 palsy) will result in unopposed lateral rectus muscle tone, resulting in lateral gaze

Question 14

Abducens nerve palsy

Answer 14

produce an inability to complete lateral gaze in the affected eye

Question 15

what signs will patients have with oculomotor nerve palsy?

Answer 15

inferior lateral gaze
ptosis - The levator palpebral superiors, also innervated by CN 3, is responsible for raising the eyelid, with paralysis resulting in ptosi
mydriasis (dilated pupil). Damage to the parasympathetic fibers of the oculomotor nerve (CN III) that usually act to constrict the pupil, will result in mydriasis (pupil dilatation

Question 16

what is the main artery supplying the orbit?

Answer 16

opthalmic artery

Question 17

Describe the vasculature of the eye

Answer 17

The opthalmic artery is the main artery supplying the eye. it branches off the internal carotid artery.
The opthalmic artery travels through the optic canal along with the optic nerve.
After entering the orbit it gives off branches - posterior ciliary arteries, lacrimal and supraorbital.
These branches supply the lacrimal gland, extraocular muscles, ethmoid and sphenoid sinuses, eyelids as well as skin over forehead and nose

Question 18

what does the nasolacrimal duct do?

Answer 18

drains lacrimal fluid from the conjunctival sac of the eye into the nasal cavity

Question 19

what are the paranasal sinuses?

Answer 19

frontal
ethmoidal
maxillary
sphenoidal

Question 20

epistaxis

Answer 20

The source of 90% of anterior nosebleeds within the Kiesselbach plexus (also known as Little’s area) on the anterior nasal septum. where branches of the maxillary, facial and ophthalmic artery converge at the antero-inferior nasal septum. Little’s area receives arterial supply from both the internal and external carotid arteries. Therefore some conservative treatments of epistaxis can be targeted at inducing vasoconstriction of these arteries.

Question 21

Posterior nosebleeds

Answer 21

These usually arise from the sphenopalatine artery (branch of maxillary artery) in the posterior nasal cavity. They may require direct tamponade of the culprit vessel in the form of a posterior nasal packing.

Question 22

What is anosmia?

Answer 22

inability to percieve odor