3.2 Orbit Flashcards
What part of the orbit are generally the thinest and present significant clinical threat of becoming fractured or eroded in persistent infection?
medial wall & floor
Fluid (tears) is drained from the medial corner of the eye through a small opening or … on the medial aspect of each eyelid.
punctum
Fluid (tears) are drained from the puncture into the … that opens into the nasal cavity?
nasolacrimal duct
The nasolacrimal duct opens into the nasal cavity under the … on the lateral wall.
inferior concha
Each eyelid contains a semilunar plate of dense CT called a …
tarsal plate
Embedded in each plate are a number of … that secrete a fatty substance keeping the lids from sticking together when closed.
tarsal glands
The tarsal plates are anchored to the orbital margin by …
medial and lateral palpebral ligaments
Voluntary (skeletal) muscle that raises the upper eyelid.
levator palpeerde superioris
In it’s raised position, an involuntary SM is responsible for the “tone” of the eyelid. (eyelid should rest just above the iris of the eye)
superior tarsal muscle (Mueller’s)
The superior tarsal muscle is innervated by … that travel with the frontal nerve
sympathetic fibers
A lesion of the SNS - superior cervical ganglion (Horner’s syndrome) causes
partial ptosis (drooping of the eyelid)
What are the eye abductor muscles?
Lateral rectus (obliques)
What are the eye adductor muscles?
Medial rectus (Superior and Inferior recti)
What are the eye elevator muscles?
Superior rectus, Inferior oblique
What are the eye depressor muscles?
Inferior rectus, Superior oblique
What are the eye intortion muscles?
Superior oblique (Superior rectus)
What are the eye extortion muscles?
Inferior oblique (Inferior rectus)
How should the pt look to test SR?
abduct and look up
How should the pt look to test IR?
abduct and look down
How should the pt look to test SO?
adduct and look down
How should the pt look to test IO?
adduct and look up
The external fibrous layer of the eye is composed of the posterior 5/6 which is … and the anterior 1/6 which is …
sclera (white of eye) and cornea
A contractile diaphragm anterior ro the lens in the middle vascular layer of the eyeball.
iris
What are the 2 muscles of the iris?
sphincter papillae and dilator pupillae
What is the principle blood supply to the orbit?
ophthalmic artery
The ophthalmic artery is a branch of the …
internal carotid artery
What is the relationship of the ophthalmic a. and the optic n. in the optic canal?
Ophthalmic artery travels superior to the optic nerve (army over navy)
The ophthalmic a. passes anteriorly toward the … wall of the orbit.
medial wall
The sup. and inf. ophthalmic veins exit the orbit via the…
superior orbital fissure
The sup. and inf. ophthalmic veins empty into the …
cavernous sinus
The sup and inf. ophthalmic veins originate in the anterior aspect of the orbit, as connecting veins from the …
supraorbital and angular veins
The frontal nerve is the largest of the V1 branches and lies on top of …
levator palpeerde superioris .
The frontal n. divides into 2 nerves, the lateral being … and the medial is …
supra-orbital n. and supratrochlear n.
What is the the lateral branch of V1?
lacrimal n.
What is the medial branch of V1?
nasociliary n.
What are branches of the nasociliary n. that convey sinus pain?
ant. and post. ethmoidal nn.
A branch of the nasociliary n. the long ciliary nn. has what function?
sensory innervation of the iris and cornea
Sympathetics hitchhike on the long ciliary nn. to innervate the …
dilator pupillae m.
What branch of the nasociliary n. originates and passes through the ciliary ganglion without synapsing?
Short ciliary nn.
The superior division of the Oculomotor n. (CN III), provides motor innervation for …
levator palpeerde superioris, superior rectus
The inferior division of the Oculomotor n. (CN III), provides motor innervation for …
medial rectus, inferior rectus, and inferior oblique
The preganlionic parasympathetic fibers travel via … of CN III, and synapse in …
inferior division, ciliary ganglion
Postsynaptic parasympathetic fibers travel via …
short ciliary nn.
Parasympathetics of the short ciliary nn. supply the … that regulates tension on lens for focusing.
sphincter papillae and ciliaris m.
What are the symptoms of Oculomotor (CN III) Palsy?
Down and outward glaze (SO and LR only not effected), dilated (no sphincter papillae), and Ptosis (no LPS)
Postganglionic sympathetic fibers travel from … to the orbit, via 2 pathways, short and long ciliary nn.
internal carotid plexus
The lacrimal gland is innervated by what cranial nerve?
Facial (CN VII)
What gives motor innervation to Superior Oblique muscle?
Trochlear (CN IV)
What are the symptoms of Trochlear (CN IV) Palsy?
Extortion (outward rotation) of the affected eye due to unopposed IO, which causes diplopia, the pt may tilt head to manually introit the eye
What are the symptoms of Abducens (CN VI) Palsy?
at rest the eye is adducted (since LR can’t abduct); when asked to gaze to one side the affected eye can’t abduct
