Orbit Anatomy Flashcards
What bones make up the roof of the orbit?
orbital part of frontal bone, lesser wing of sphenoid
What bones make up the medial wall of the orbit?
ethmoid bone, frontal bone, lacrimal bone, sphenoid bone
What bones make up the inferior wall of the orbit?
maxilla, zygoma, palatine bone
What bones make up the lateral wall of the orbit?
zygoma, greater wing of sphenoid
What are the seven bones that contribute to the orbit?
maxilla, zygomatic, frontal, ethmoid, lacrimal, sphenoid, palatine
What travels through the optic canal?
optic nerve (CNII) and ophthalmic artery
What travels through the superior orbital fissure?
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
What travels through the inferior orbital fissure?
orbital branches of V2–zygomatic nerve and infraorbital nerve; and infraorbital artery
The anterior and posterior ethmoidal foramina conduct what structures from where to where?
anterior and posterior ethmoidal nerves and vessels from orbit into ethmoid bone
What nerves synapse in the ciliary ganglion?
pre-ganglionic parasympathetics of CNIII destined for smooth muscle (constrictor pupillae and ciliary muscles) in the eyeball
The lacrimal artery is a branch off what artery?
ophthalmic artery
The anterior and posterior ethmoidal arteries are branches off what artery?
ophthalmic artery
What fibers travel with the short ciliary nerves?
post-ganglionic parasympathetics of CNIII
post-ganglionic sympathetics
GVA via V1
What are signs of loss of sympathetic innervation to the eyes?
anhydrosis, miosis, ptosis, enopthalmos (Horner’s syndrome)
What are signs of parasympathetic loss in the eyes?
loss of accommodation, mydriasis, loss of lacrimation
Where are the cell bodies of the ophthalmic nerve located?
trigeminal/semilunar ganglion
What are the 3 major branches of the ophthalmic (V1) nerve?
lacrimal nerve
frontal nerve
nasociliary nerve
The ophthalmic veins drain to what 2 vein(s)/sinus(es)?
cavernous sinus and pterygoid plexus
What is the Annulus of Zinn, aka tendinous ring?
a ring of fibrous tissue surrounding the optic nerve at its entrance at the apex of the orbit
The medial rectus moves the eyeball which direction?
medially
The lateral rectus moves the eyeball which direction?
laterally
The superior oblique moves the eyeball which direction?
down and out: depresses and lalterally rotates
The inferior oblique moves the eyeball which direction?
up and out: elevates and laterally rotates
The inferior rectus moves the eyeball which direction?
down and in: depresses and medially rotates
The superior rectus moves the eyeball which direction?
up and in: elevates and medially rotates
How do you test specific muscle of the orbit?
shorten the muscle you’re not interested in, then elevate/depress the eye depending on the muscle you are testing
What four muscles of the orbit originate from the common tendinous ring?
superior rectus, medial rectus, inferior rectus, lateral rectus
The superior branch of oculomotor nerve (CNIII) innervates what muscle(s)?
levator palpebrae superioris, superior rectus
The inferior branch of oculomotor nerve (CNIII) innervates what muscle(s)?
medial rectus, inferior rectus, inferior oblique
Dilation and constriction of the pupil are under antagonistic control by ___ and ___ efferents respectively
sympathetic; parasympathetic
Pupillary constriction is under what autonomic control?
parasympathetic
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.
decreases; ciliary body; decreases
What types of fibers run in the long ciliary nerve?
sensory and sympathetic fibers coming from the nasociliary nerve
What nerve carries pain from the eyeball, like when you get something in your eye?
V1-ophthalmic nerve
What types of fibers run in the short ciliary nerve?
sensory, post-ganglionic sympathetic, and post-ganglionic parasympathetic
Describe the corneal reflex.
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
Describe sympathetic innervation of the lacrimal gland.
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
Describe parasympathetic innervation of the lacrimal gland.
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
What motion would be used to test the medial rectus muscle?
ask the patient to look medially
What motion would be used to test the lateral rectus muscle?
ask the patient to look laterally
What motion would be used to test the superior rectus muscle?
ask the patient to look laterally and up
What motion would be used to test the inferior rectus muscle?
ask the patient to look laterally and down
What motion would be used to test the superior oblique muscle?
ask the patient to look medially and down
What motion would be used to test the inferior oblique muscle?
ask the patient to look medially and up
The lateral rectus muscle is innervated by what nerve?
abducent nerve, CN VI
The medial rectus muscle is innervated by what nerve?
oculomotor nerve, CN III
The superior oblique muscle is innervated by what nerve?
trochlear nerve, CN IV
The inferior and superior rectus muscles are innervated by what nerve?
oculomotor nerve, CN III
