[16] Muscles of the Eye Flashcards
How many muscles control the movements of the eyeball?
6
What are the categories of muscle controlling the eye?
- Recti (4)
- Oblique (2)
What do all the recti muscles of the eye arise from?
Common tendinous ring
What is the common tendinous ring?
A fibrous cuff that surrounds the optic canal
Draw a diagram illustrating the action of muscles on the eyeball
What is the origin of the superior rectus?
Superior part of the common tendionous ring
What is the insertion of the superior rectus?
Superior and anterior aspect of sclera
What is the innervation of the superior rectus?
Oculomotor nerve
What is the action of the superior rectus?
- Elevation
- Contributes to adduction and medial rotation
What is the origin of the inferior rectus?
Inferior part of common tendinous ring
What is the insertion of the inferior rectus?
Inferior and anterior aspect of the sclera
What is the innervation of the inferior rectus?
Oculomotor nerve
What is the action of the inferior rectus?
- Depression
- Contributes to the adduction and lateral rotation of the eyeball
What is the origin of the medial rectus?
Medial part of common tendinous ring
What is the insertion of the medial rectus?
Antero-medial aspect of sclera
What is the innervation of the medial rectus?
Oculomotor nerve
What is the action of the medial rectus?
Adducts
What is the origin of the lateral rectus?
Lateral part of the common tendinous ring
What is the insertion of the lateral rectus?
Antero-lateral aspect of sclera
What is the innervation of the lateral rectus?
Abducens nerve
What is the action of the lateral rectus?
Abducts
What is the origin of the superior oblique?
Body of sphenoid bone
What is the insertion of the superior oblique?
Sclera of eye, posterior to superior rectus
What is the innervation of the superior oblique?
Trochlear nerve
What is the action of the superior oblique?
Depresses, abducts, and medially rotates
What is the origin of the inferior oblique?
Anterior aspect of the orbital floor
What is the insertion of the inferior oblique?
Sclera of eye, posterior to lateral rectus
What is the innervation of the inferior oblique?
Oculomotor nerve
What is the action of the inferior oblique?
Elevates, abducts, and laterally rotates the eyeball
What does movement of the eyelids occur via the action of?
- Orbicularis oculi muscle
- Levator palpebrae superioris muscle
What does the orbicularis oculi muscle do?
Closes the eyelid
What is the orbicularis oculi muscle innervated by?
The facial nerve
What does the levator palpebrae superioris muscle do?
Opens the eyelid
What is the leavtor palpebrae superioris muscle innervated by?
The oculomotor nerve
What is complete ptosis caused by?
A CN III lesion
What is partial ptosis caused by?
A sympathetic lesion
