How Do the Extra-Ocular Eye Muscles Differ in Action from the Intrinsic

Question

How do the extra-ocular eye muscles differ in action from the intrinsic eye muscles?
A) The two muscle groups do not differ in movement types, only in when the movements occur.
B) The extra-ocular muscles cause faster movements than do the intrinsic muscles.
C) Extra-ocular eye muscles move the eyeball in relation to the rest of the body, whereas intrinsic muscles move structures within the eyeball.
D) The extra-ocular eye muscles are smooth muscles inside the eyeball while the intrinsic eye muscles originate on the surface of the orbit and insert into the sclera of the eye just posterior to the cornea.
E) None of the answers are correct.

Accepted Answer

Extra-ocular eye muscles move the eyeball in relation to the rest of the body and are responsible for eye movements such as tracking and fixation. In contrast, intrinsic eye muscles are responsible for changing the shape of structures within the eye, such as the lens for focusing.