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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 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 ...
Schematic diagram of the human eye. It shows a horizontal section through the right eye. The eye is made up of three coats, or layers, enclosing various anatomical structures. The outermost layer, known as the fibrous tunic, is composed of the cornea and sclera, which provide shape to the eye and support the deeper structures.
The muscles it controls are the striated muscle in levator palpebrae superioris and other extraocular muscles except for the superior oblique muscle and the lateral rectus muscle. The Edinger-Westphal nucleus supplies parasympathetic fibers to the eye via the ciliary ganglion , and thus controls the sphincter pupillae muscle (affecting pupil ...
The medial rectus muscle is a muscle in the orbit near the eye. It is one of the extraocular muscles. It originates from the common tendinous ring, and inserts into the anteromedial surface of the eye. It is supplied by the inferior division of the oculomotor nerve (III). It rotates the eye medially (adduction).
Six extraocular muscles facilitate eye movement. These muscles arise from the common tendinous ring (annulus of Zinn) in the orbit (eye cavity), and attach to the eyeball. The six muscles are the lateral, medial, inferior and superior recti muscles, and the inferior and superior oblique muscles. The muscles cause movement of the eyeball by ...
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.
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.