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The extraocular muscles, or extrinsic ocular muscles, are the seven extrinsic muscles of the eye in humans and other animals. [1] Six of the extraocular muscles, the four recti muscles, and the superior and inferior oblique muscles, control movement of the eye. The other muscle, the levator palpebrae superioris, controls eyelid elevation.
The vestibulo-ocular reflex is a reflex eye movement that stabilizes images on the retina during head movement by producing an eye movement in the direction opposite to head movement in response to neural input from the vestibular system of the inner ear, thus maintaining the image in the centre of the visual field. For example, when the head ...
Intrinsic ocular muscles [1] or intraocular muscles [2] are muscles of the inside of the eye structure. The intraocular muscles are responsible for the protraction and retraction of the eyelids and reaction to light and pupil accommodation. [2] They're different to the extraocular muscles that are outside of the eye and control the external ...
The extraocular muscles rotate the eyeball around vertical, horizontal and antero-posterior axes. Extraocular muscles other than the medial rectus and lateral rectus have more than one action due to the angle they make with the optical axis of the eye while inserting into the eyeball. The superior and inferior oblique muscles make an angle of ...
The palpebral portion of the muscle is thin and pale; it arises from the bifurcation of the medial palpebral ligament, forms a series of concentric curves, and is inserted into the lateral palpebral raphe at the outer canthus (corner) of the eye. [3] The palpebral portion contains the preseptal and pretarsal muscles.
To summarize, the actions of the superior oblique muscle are (1) depression of the eyeball, especially when the eye is adducted; and (2) intorsion of the eyeball, especially when the eye is abducted. The clinical consequences of weakness in the superior oblique (caused, for example, by fourth nerve palsies) are discussed below.
This "Figure Eight" exercise works the muscles differently by moving the head and keeping the eyes in place. Stare at a fixed object straight ahead. Close one eye.
The iris sphincter muscle (pupillary sphincter, pupillary constrictor, circular muscle of iris, circular fibers) is a muscle in the part of the eye called the iris.It encircles the pupil of the iris, appropriate to its function as a constrictor of the pupil.