Orbit anatomy/development Flashcards
What is the function of the lateral rectus?
Abducts pupil (look outward)
What is D?
Visual retina
What is the lens placode? What structures arise from it?
A thickening of the surface ectoderm, develops into the lens
What is S?
Venous sinus
What is the anterior chamber of the eye?
The chamber between the cornea and iris
What is the function of the superior oblique?
Abducts and depresses pupil (look down and out)
What is K?
Macula
What is the function of the superior rectus?
Adducts and elevates pupil (look up and in)
What is Q?
Cornea
What does this image suggest?
Graves orbitopathy (big eye muscles, bulging eyes)
What does the optic nerve (II) do for the eye?
It provides special sensory neurons for vision
What is R?
Irido-corneal angle
What is E?
Choroid
What is G?
Subarachnoid space and pia
What causes dilated pupils?
Loss of parasympathetic innervation to the pupil constrictor fibers
What is the result of trochlear nerve damage?
Difficulty depressing the eye from an adducted position
What is F?
Dura and arachnoid
What is N?
Suspensory ligaments
What is the purpose of the aqueous humor in the eye?
It provides metabolic exchange with the avascular cornea (and lens)
Pain when trying to focus for close up vision might indicate an infection in which of the following?
a) orbicularis oculi
b) cornea
c) choroid layer
d) pupil dilator
e) ciliary body
e) ciliary body
ciliary body has the muscle that contracts to allow the lens to round up for close up vision
What is L?
Infraorbital foramen
What is a detached retina?
A blow to the head can cause the visual retina to fall away from the pigmented retina because they are never fully fused
What is Bell’s palsy?
Facial nerve (VII) dysfunction and the resulting loss of the actions of the muscles of facial exxpression
What is Horner’s syndrome?
Damage to sympathetic organization that causes ptosis secondary to a mullers muscle abnormality
Associated with miosis (constricted pupil) and anhydrosis (no sweating)
What bones make up the lateral wall of the orbit?
Greater wing of sphenoid bone, zygomatic bone
What are three causes of neurogenic ptosis?
Horner’s syndrome
cranial nerve 3 palsy
myasthenia gravis
C - Optic nerve
this is the lesser wing of the sphenoid bone with the optic canal that contains the optic nerve and ophthalmic artery
What is the testing position for the inferior oblique?
Look in and up
How do you test for ocular eye motion generally?
If its a muscle with only one function (ex. lateral rectus), just do that function
If its a muscle with two functions, you would have them move the typical direction vertically (either up or down) and have their eye positioned the oposite direction horizontally (either out or in) - ex. for superior rectus have them look outward and then up
What is the ectodermal optic cup? What structures arise from it?
It is an extension of the neural tube
It gives rise to the optic nerve, visual retina, and pigmented retina (part of the iris and ciliary body)
What is blepharitis?
Chronic inflammation of lid margin - causes foreign body sensation, burning, mattering, redness
What is the structure of the sclera?
It is continuous with the cornea and formed from vascular collagen fibers in random orientation
What is A?
Iris
Which muscles adduct the pupils?
Medial rectus, superior rectus, inferior rectus
What are the nerve fibers of the facial nerve (VII)?
Branchiomotor fibers to the orbicularis oculi muscle, presynaptic parasympathetics for the lacrimal gland
What is the testing position for the inferior rectus?
Look out and down
What is N?
Perpendicular plate of the ethmoid bone
What is A?
Medial rectus
What is the result of oculomotor nerve damage?
Down and out position (only lateral rectus and superior oblique working), pupil dilated (loss of parasympathetics), eyelid droopy (loss of levator palpebrae superioris)
What is the posterior chamber of the eye?
The chamber between the iris and lens where aqueous humor is produced
What soft tissue is related to the optic canal in lesser wing of sphenoid?
Optic nerve and ophthalmic artery
What condition does this image suggest?
Graves orbitopathy
What is Graves orbitopathy?
A thyroid eye disease that causes soft tissue swelling and scaring that can lead to proptosis, double vision, and vision loss (compressed optic nerve)
What is I?
Optic disc
What is the difference between preseptal cellulitis and orbital cellulitis?
Preseptal is anterior to the orbital septum and is not as serious (orbital cellulitis can spread to brain)
What is the path of aqueous humor in the eye?
It is produced in the posterior chamber, passes through the pupil to the anterior chamber where it enters venous circulation via the scleral venous sinus
What is E?
Nasal bone
What types of nerves are in the ophthalmic division of the trigeminal nerve?
General sensory fibers, postsynaptic parasympathetic fibers from ciliary ganglion (originating in nerve III), and postsynaptic sympathetics (cell bodies in superior cervical ganglion of sympathetic trunk)
What is C?
Inferior rectus
What is J?
Central artery and vein of retina
What soft tissue is related to the supraorbital notch/foramen?
Supraorbital nerve (V1 branch of trigeminal)