The muscles that move the eyeballs are
extrinsic
muscles because they originate outside the eyeball and
are inserted on the outer surface (ex- = out of). They
move the eyeballs in various directions.
These muscles are among the fastest contracting and
most precisely controlled skeletal muscles in the body.
These muscles are illustrated in
Figure 6.15
, which also
provides their respective origins, insertions, and actions.
M uscles o f th e h ea d th a t m ove th e eyeb alls and u p p e r eyelids • Figure 6.15
Superior oblique
Levator palpebrae
superioris (cut)
Superior rectus
Medial
Lateral rectus
Inferior rectus
Inferior oblique
Lateral view of right eyeball
Muscle
Origin
Insertion
Action
Muscles of the head that move the eyeballs and upper eyelids
Superior rectus
(REK-tus)
Tendinous ring attached
to bony orbit around
optic foramen
Superior and central part of
eyeball
Moves eyeball upward (elevation) and
medially (adduction) and rotates it
medially
Lateral rectus
Same as above
Lateral side of eyeball
Moves eyeball laterally (abduction)
Medial rectus
Same as above
Medial side of eyeball
Moves eyeball medially (adduction)
Superior oblique
(o-BLEK)
Same as above
Eyeball between superior and
lateral recti; the muscle moves
through a ring of fibrocartilaginous
tissue called the trochlea
Moves eyeball downward (depression)
and laterally (abduction) and rotates it
medially
Inferior oblique
Maxilla
Eyeball between inferior and
lateral recti
Moves eyeball upward (elevation)
and laterally (abduction) and rotates it
laterally
Levator palpebrae superioris
(le-VA-tor PAL-pe-bre
soo-per'-e-OR-is)
Roof of orbit
Skin of upper eyelid
Elevates upper eyelid (opens eye)
174 CHAPTER 6
The Muscular System
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