Fundamentals Vol. 1 Flashcards
How many short ciliary nerves are there in each eye?
Approx. 6 to 10
What is the order that the rectus muscles insert into the globe, starting closest to the limbus?
Medial rectus, Inferior rectus, Lateral rectus, Superior rectus (Think “MILS”)
What is the name of the imaginary line drawn through the insertion sites of the rectus muscles?
Spiral of Tillaux
What is the insertion site of the medial rectus muscle?
5.5 mm from the medial limbus
What is the insertion site of the inferior rectus muscle?
6.5 mm from the inferior limbus
What is the insertion site of the lateral rectus muscle?
6.9 mm from the lateral limbus
What is the insertion site of the superior rectus muscle?
7.7 mm from the superior limbus
What is the blood supply to the medial rectus muscle?
Inferior muscular branch of the ophthalmic artery
What is the blood supply to the inferior rectus muscle?
Inferior muscular branch of the ophthalmic artery and infraorbital artery
What is the blood supply to the lateral rectus muscle?
Lacrimal artery
What is the blood supply to the superior rectus muscle?
Superior muscular branch of the ophthalmic artery
What is the blood supply to the superior oblique muscle?
Superior muscular branch of the ophthalmic artery
What is the blood supply to the inferior oblique muscle?
Inferior muscular branch of the ophthalmic artery and infraorbital artery
What is the longest extraocular muscle?
Superior rectus (41.8 mm)
What is the shortest extraocular muscle?
Inferior oblique (37 mm)
What is the the only extraocular muscle without a tendon at Its Insertion?
Inferior oblique
What extraocular muscle has the longest tendon?
Superior oblique (20 mm)
What Is the orgin of the superior oblique muscle?
Body of the sphenoid bone (Medial to optic foramen, between the annulus of Zinn and the periorbital)
Where does the superior oblique muscle insert?
Under the superior rectus muscle, posterior to the center of rotation
What is the origin of the inferior oblique muscle?
Orbital floor of the maxillary bone near the lacrimal fossa
Where does the inferior oblique muscle insert?
Posterior, Inferior temporal quadrant at the level of the macula
What extraocular muscle has the shortest tendon?
Medial rectus
What muscles does the superior division of CN Ill innervate?
Levator palpebra and superior rectus muscle
What muscles does the inferior division of CN Ill lnnvervate?
Medial rectus, inferior rectus, and inferior oblique muscle
What is the ratio of nerve fibers to muscle fibers of the extraocular muscles?
1:3 to 1:5 (compared to 1:50 of skeletal muscle)
What type of muscle fibers are unique to extraocular muscles?
Slow, tonic type (Felderstruktur)
What are the slow, tonic fibers of extraocular muscles useful for?
Smooth pursuit
What is the origin of the levator palpebrae muscle?
Lesser wing of the sphenoid (superior to the annulus of Zinn)
What type of nerve endings do the slow, tonic fibers of the extraocular muscles have?
Multiple, grapellke nerve endings (en grappe)
What type of nerve endings do the fast twitch fibers of the extraocular muscles have?
Platelike nerve endings (en plaque)
What type of nerve endings do the fast, twitch fibers of the extraocular muscles have?
Platelike nerve endings (en plaque)
What do the fast, twitch fibers of the extraocular muscles aid with?
Rapid, saccadic movements
