Orbit II Flashcards
Name the 4 rectus muscles of the eye
- superior rectus
- inferior rectus
- lateral rectus
- medial rectus
Name the 2 oblique muscles of the eye
- Superior oblique
- Inferior oblique
What makes up the common tendinous ring
Point of origin of 4 of the the muscles of the orbit
- superior rectus
- Inferior rectus
- Lateral rectus
- Medial rectus
encloses optic canal and superior orbital fissure
What is the insertion and action of the levator palpebrae superioris muscle?
- Insertion: superior tarsal plate
- action: elevate upper eyelid
What is the innervation of the Levator Palpebrae superioris m. and Superior rectus m.
Superior division of oculomotor (CN III)
What nerve innervates lateral rectus m.
abducent (CN VI)
What nerve innervates inferior rectus m. and medial rectus m.
inferior division of oculomotor (CN III)
What nerve innervates the superior oblique m.
Trochlear (CN IV)
What nerve innervates the inferior oblique m.
inferior division of oculomotor CN III
What is the action of the medial rectus m.
STRONG adduction
Action of lateral rectus
STRONG ABduction
What is the action of the superior rectus m.
Strong elevation
Slight adduction
Intorsion
- muscle lies at a angle from the medial wall of the orbit
What is the action on inferior rectus m.
- strong depression
- slight adduction
- extorsion
What is the action of the superior oblique
- strong depression
- slight abduction
- intorsion
What is the action of the inferior oblique m.
- strong elevation
- slight abduction
- extorsion
intorsion vs extorsion
Rotation of upper cornea toward (intorsion) or away (Extorsion) from midline
How can you test if a patient’s superior oblique m. is not functioning?
Have him/her adduct the eye (via medial rectus) and now superior oblique is a pure depressor
* inferior rectus cannot depress in this state; it now produces pure extorsion
How can you check to see if superior rectus m. is functioning?
Have patient Abduct his/her eye (via lateral rectus); superior rectus is now a pure elevator
- inferior oblique cannot elevate; it ow produces pure extorsion
Name the two divisions of the oculomotor nerve (CN III).
- Superior and Inferior division
The superior division of oculomotor n (CN III) gives motor innervation to what 2 muscles?
- superior rectus
- Levator palpebrae superioris
The inferior division supplies what (3 muscles) and has what type of innervation
- medial rectus
- inferior rectus
- inferior oblique
- motor; preganglionic parasympathetics
How can you distinguish the trochlear nerve after it exits the superior orbital fissure
passes along the superior surface of the superior oblique muscle
How can you distinguish the abducent nerve (CN VI) after it exits the superior orbital fissure
passes along the medial side of the lateral rectus muscle
any nerve passing through the superior orbital fissure passes through what sinus
cavernous sinus
Identify purple arrow
cavernous sinus
identify blue
oculomotor (III)
orange
Trochlear n ( CN IV)
black
ophthalmic n. of trigeminal (CN V1)
green
maxillary nerve of trigeminal (CN V2)
identify
abducent nerve
