Orbit Anatomy

Question 1

What bones make up the roof of the orbit?

Answer 1

orbital part of frontal bone, lesser wing of sphenoid

Question 2

What bones make up the medial wall of the orbit?

Answer 2

ethmoid bone, frontal bone, lacrimal bone, sphenoid bone

Question 3

What bones make up the inferior wall of the orbit?

Answer 3

maxilla, zygoma, palatine bone

Question 4

What bones make up the lateral wall of the orbit?

Answer 4

zygoma, greater wing of sphenoid

Question 5

What are the seven bones that contribute to the orbit?

Answer 5

maxilla, zygomatic, frontal, ethmoid, lacrimal, sphenoid, palatine

Question 6

What travels through the optic canal?

Answer 6

optic nerve (CNII) and ophthalmic artery

Question 7

What travels through the superior orbital fissure?

Answer 7

Lacrimal n.
Frontal n.
Trochlear n. 
Sup. Ophthalmic v. 
Sup. Div. of CN III
Nasociliary n. 
Inf. Div. of CN III
Abducent n. 
Inf. Ophthalmic v. 

*Mnemonic for nerves: Luscious French Torts Sit Nestled In Anticipation

Question 8

What travels through the inferior orbital fissure?

Answer 8

orbital branches of V2–zygomatic nerve and infraorbital nerve; and infraorbital artery

Question 9

The anterior and posterior ethmoidal foramina conduct what structures from where to where?

Answer 9

anterior and posterior ethmoidal nerves and vessels from orbit into ethmoid bone

Question 10

What nerves synapse in the ciliary ganglion?

Answer 10

pre-ganglionic parasympathetics of CNIII destined for smooth muscle (constrictor pupillae and ciliary muscles) in the eyeball

Question 11

The lacrimal artery is a branch off what artery?

Answer 11

ophthalmic artery

Question 12

The anterior and posterior ethmoidal arteries are branches off what artery?

Answer 12

ophthalmic artery

Question 13

What fibers travel with the short ciliary nerves?

Answer 13

post-ganglionic parasympathetics of CNIII
post-ganglionic sympathetics
GVA via V1

Question 14

What are signs of loss of sympathetic innervation to the eyes?

Answer 14

anhydrosis, miosis, ptosis, enopthalmos (Horner’s syndrome)

Question 15

What are signs of parasympathetic loss in the eyes?

Answer 15

loss of accommodation, mydriasis, loss of lacrimation

Question 16

Where are the cell bodies of the ophthalmic nerve located?

Answer 16

trigeminal/semilunar ganglion

Question 17

What are the 3 major branches of the ophthalmic (V1) nerve?

Answer 17

lacrimal nerve
frontal nerve
nasociliary nerve

Question 18

The ophthalmic veins drain to what 2 vein(s)/sinus(es)?

Answer 18

cavernous sinus and pterygoid plexus

Question 19

What is the Annulus of Zinn, aka tendinous ring?

Answer 19

a ring of fibrous tissue surrounding the optic nerve at its entrance at the apex of the orbit

Question 20

The medial rectus moves the eyeball which direction?

Answer 20

medially

Question 21

The lateral rectus moves the eyeball which direction?

Answer 21

laterally

Question 22

The superior oblique moves the eyeball which direction?

Answer 22

down and out: depresses and lalterally rotates

Question 23

The inferior oblique moves the eyeball which direction?

Answer 23

up and out: elevates and laterally rotates

Question 24

The inferior rectus moves the eyeball which direction?

Answer 24

down and in: depresses and medially rotates

Question 25

The superior rectus moves the eyeball which direction?

Answer 25

up and in: elevates and medially rotates

Question 26

How do you test specific muscle of the orbit?

Answer 26

shorten the muscle you're not interested in, then elevate/depress the eye depending on the muscle you are testing

Question 27

What four muscles of the orbit originate from the common tendinous ring?

Answer 27

superior rectus, medial rectus, inferior rectus, lateral rectus

Question 28

The superior branch of oculomotor nerve (CNIII) innervates what muscle(s)?

Answer 28

levator palpebrae superioris, superior rectus

Question 29

The inferior branch of oculomotor nerve (CNIII) innervates what muscle(s)?

Answer 29

medial rectus, inferior rectus, inferior oblique

Question 30

Dilation and constriction of the pupil are under antagonistic control by ___ and ___ efferents respectively

Answer 30

sympathetic; parasympathetic

Question 31

Pupillary constriction is under what autonomic control?

Answer 31

parasympathetic

Question 32

Contraction of the ciliary muscle ___(dec/inc) the size of the ring formed by the ___ ___. This ___(dec/inc) tension on the suspensory ligament of the lens.

Answer 32

decreases; ciliary body; decreases

Question 33

What types of fibers run in the long ciliary nerve?

Answer 33

sensory and sympathetic fibers coming from the nasociliary nerve

Question 34

What nerve carries pain from the eyeball, like when you get something in your eye?

Answer 34

V1-ophthalmic nerve

Question 35

What types of fibers run in the short ciliary nerve?

Answer 35

sensory, post-ganglionic sympathetic, and post-ganglionic parasympathetic

Question 36

Describe the corneal reflex.

Answer 36

something irritates the cornea, sensation is carried by V1-ophthalmic; synapse in the brain stem tells CN VII to orbicularis oculi orbit muscle to tightly shut the eye; eye reopened later by levator palpebrae superioris innervated by CNIII

Question 37

Describe sympathetic innervation of the lacrimal gland.

Answer 37

from thoracic chain - superior cervical ganglion - cervical plexus - become the deep petrosal nerve - join fibers of greater petrosal nerve to become nerve of the pterygoid canal; pass through pterygopalatine ganglion (no synapses) to innervate the lacrimal gland

Question 38

Describe parasympathetic innervation of the lacrimal gland.

Answer 38

pre-ganglionics: from superior salivatory nucleus; run in CN VII - greater petrosal nerve - nerve of pterygoid canal - synapse in pterygopalatine ganglion. Post-ganglionics: travel with maxillary nerve - zygomatic nerve - lacrimal branch of ophthalmic nerve, then innervate the gland

Question 39

What motion would be used to test the medial rectus muscle?

Answer 39

ask the patient to look medially

Question 40

What motion would be used to test the lateral rectus muscle?

Answer 40

ask the patient to look laterally

Question 41

What motion would be used to test the superior rectus muscle?

Answer 41

ask the patient to look laterally and up

Question 42

What motion would be used to test the inferior rectus muscle?

Answer 42

ask the patient to look laterally and down

Question 43

What motion would be used to test the superior oblique muscle?

Answer 43

ask the patient to look medially and down

Question 44

What motion would be used to test the inferior oblique muscle?

Answer 44

ask the patient to look medially and up

Question 45

The lateral rectus muscle is innervated by what nerve?

Answer 45

abducent nerve, CN VI

Question 46

The medial rectus muscle is innervated by what nerve?

Answer 46

oculomotor nerve, CN III

Question 47

The superior oblique muscle is innervated by what nerve?

Answer 47

trochlear nerve, CN IV

Question 48

The inferior and superior rectus muscles are innervated by what nerve?

Answer 48

oculomotor nerve, CN III