Extra-Ocular Muscles Flashcards
What are the muscles of the orbit?
Levator Palpebrae Superioris
Superior, Inferior, Medial, Lateral Recti Muscles
Superior Oblique Muscle
Inferior Oblique Muscle
Levator Palpebrae Superioris
Description
Thin, triangular muscle
Levator Palpebrae Superioris
It is always active except ____
__when the eye is closed__
Levator Palpebrae Superioris
Origin
Roof of Orbit above Optic Canal
Levator Palpebrae Superior
Insertion
Forms wide aponeurosis inserting into:
Skin of Upper Eyelid innervated by Occulomotor Nerve
Anterior part of Superior Tarsus (muscle fibers called superior tarsal muscle) innervated by sympathetic trunk
Levator Palpebrae Superioris
Action
Elevation of upper eyelid
Levator Palpebrae Superioris
Ptosis is caused by
Oculomotor Nerve damage
Cervical Sympathetic Trunk damage
Ptosis is a symptom of Horner’s Syndrome
Horner’s Syndrome is caused by …
damage of sympathetic nerves of the eye
What are the symptoms of Horner’s Syndrome?
Ptosis
Miosis (constriction of pupil)
Anhydrosis
What are the axes of the eyeball?
Horizontal Axis
Vertical Axis
Antero-posterior axes
Axes of Eye
What does the horizontal axis divide the eyeball into?
Anterior and Posterior
Axes of Eye
What does the vertical axis divide the eyeball into?
Medial and Lateral
Axes of Eye
What does the anteroposterior axis divide the eyeball into?
Medial and Lateral
Recti Muscles
What are the 4 recti muscles?
Superior Rectus
Inferior Rectus
Medial Rectus
Lateral Rectus
Recti Muscles
Origin
Common Tendinous Ring surrounding Optic Canal
Junction of Superior and Inferior Orbital Fissure
Recti Muscles
Pathway
Run anteriorly and attach anterior to horizontal axis
Recti Muscles
Insertion of Medial Rectus
Attach to medial side of eyeball anterior to horizontal axis
Recti Muscles
Insertion of Lateral Rectus
Attach to lateral side of eyeball anterior to horizontal axis
Recti Muscles
Insertion of Superior Rectus
Attaches to superior side of eyeball anterior to horizontal axis (on medial side)
Recti Muscles
Insertion of Inferior Rectus
Attaches to inferior side of eyeball anterior to horizontal axis (on medial side)
Recti Muscles
Action of Lateral Rectus
Abduction
Recti Muscles
Action of Medial Rectus
Adduction
Recti Muscles
Action of Superior Rectus
Elevates
Adduction
Reminder: Superior Rectus inserts on medial surface of eyeball enabling adduction
Rectus Muscles
Action of Inferior Rectus
Depression
Adduction
Reminder: Superior Rectus inserts on medial surface of eyeball enabling adduction
Superior Oblique Muscles
Origin
Sphenoid Bone Superomedial to Common Tendinous Ring
Superior Oblique Muscles
Pathway
Passes anteriorly above medial rectus
Ends as round tendon which runs through trochlea
Superior Oblique Muscle
Insertion
Tendon runs posterolaterally from trochlea and inserts into sclera on superior surface posterior to horizontal axis and lateral to AP+Vertical axes
Superior Oblique Muscle
Action
Depression
Abduction
Inferior Oblique Muscle
Origin
Maxilla in floor of orbit lateral to lacrimal groove
Inferior Oblique Muscle
Pathway
Pass laterally and posteriorly below Inferior Rectus
Inferior Oblique Muscle
Insertion
Into Sclera inferiorly
Posterior to Horizontal Axis and Lateral to AP and Vertical Axes
Inferior Oblique Muscle
Action
Elevation
Abduction
Cranial Nerves supplying Eye Muscles
Occulomotor Nerve
Trochlear Nerve
Abducent Nerve
How do the nerves supplying the eye muscles enter the orbit?
Superior Orbital Fissure
Nerves supplying each muscle
SO4(LR6)3:
Superior Oblique: Trochlear
Lateral Rectus: Abducent
Remaining: Oculomotor Nerve
