Orbit Flashcards
•Prevention of drying of the cornea is a major function of CN__________ and _________.
V AND VII
*If the surface of the eye dries out, even for a day or two, the cornea will be completely destroyed. That’s why dry eye is an important clinical condition.
•CN III, IV, VI are centrally placed in the head around the _____________ sinus, so any issues like double vision constitute an immediate medical emergency.
cavernous
Functions of the Orbit
- Protects the eye
- Provides a stable platform for the precise eye movements that are necessary for clear vision
- Provides passage for neurovascular structures serving the face
The very back of the orbit is called the __________.
apex.
What travels through the optic canal?
CN II and the ophthalmic artery
What travels through the superior orbital fissure?
CNS III, IV, V1, VI, ophthalmic vein
Does the frontal nerve inenrvate anything in the orbit?
No. Just passes through
Conjunctiva, and especially, Cornea are richly innervated by __________
V1
Closure of eyelids is by ________- innervated muscles
VII
The cornea is ____________ (avascular/vascular).
Avascular
*But can be transplanted and even harvested from cadavers for transplants
The oblicularis oculi muscle originates from the _________, circles around the eye and then comes back to insert onto the _______________.
medial palpebral ligament; medial palpebral ligament
Levator palpebrae superioris is the striated muscle that opens eye; it is innervated by __________. Deep to that is the ____________, which is actually a smooth muscle that allows the eyelid to fit to the curvature of the eye.
CN III; superior tarsal muscle
NOTE: Because it is smooth muscle, the superior tarsal muscle has sympathetic innervation from the ANS
Infection of the ciliary glands is called a ____________
“sty”.
____________generate a hydrophobic, lipid-rich secretion that forms a surface film on the lacrimal fluid and helps prevents lacrimal fluid overflow at the rim.
Tarsal glands
Blockage and infection of the tarsal glands results in a __________.
tarsal chalazion
The lacrimal gland is divided into superficial and deep portions by a sheet of tissue, the tendon of the______________. The gland has excretory ducts that dump tears into the conjunctival space, superior-laterally.
levator palpebrae superioris
The lacrimal nerve is a branch of ___________ and lacrimal artery is a branch of the __________. Both supply to lacrimal gland, which receives autonomic parasympathetic innervation.
CN V1; ophthalmic artery.
The puncta also lead into the superior and inferior _____________, which drain into the lacrimal sac.
lacrimal ducts
The lacrimal sac drains into the ___________, which opens up into the ___________ of the nasal cavity.
nasolacrimal duct; inferior meatus
What is the flow of the drainage of tears?
Drainage of tears: From lacrimal gland-> conjunctiva, across surface of cornea-> punta-> superior and inferior lacrimal ducts-> nasolacrimal sac-> nasolacrimal duct-> nasal cavity.
That’s how your nose runs when you cry.
Parasympathetic secretomotor innervation of the lacrimal gland
- Lacrimal subdivision of superior salivatory nucleus in caudal pons
- Facial nerve in temporal bone
- Greater petrosal nerve out of temporal bone into pterygoid canal
- Into pterygopalatine fossa to synapse with cells of pterygopalatine ganglion
5. Zygomatic branch of V2
6. Communicating branch to lacrimal nerve (V1 )
_____________ is a branch of CN VII that provides parasympathetic innervation to the lacrimal gland, for tear production.
The greater petrosal nerve
The anterior ethmoidal nerve continues downward to provide cutaneous innervation to the __________.
tip of the nose
_____________also gives rise to the nerve to the ciliary ganglion, and the long ciliary nerves, which enter the eyeball proper.
Nasociliary nerve
