What muscles produce Intorsion?
The primary (main) action of the superior oblique muscle is intorsion (internal rotation), the secondary action is depression (primarily in the adducted position) and the tertiary action is abduction (lateral rotation). The extraocular muscles rotate the eyeball around vertical, horizontal and antero-posterior axes.
What are the intraocular muscles?
The intraocular muscles include the ciliary muscle, the sphincter pupillae, and the dilator pupillae. [1] The ciliary muscle is a smooth muscle ring that controls accommodation by altering the shape of the lens, as well as controlling the flow of aqueous humor into Schlemm’s canal.
How many muscles are intraocular?
There are three intraocular muscles. Two are in the iris—the sphincter pupillae and the dilator pupillae. The third is in the ciliary body and is called the ciliary muscle.
What are rectus muscles?
The rectus muscles move the eyes about the longitudinal axis of the body, that is, superiorly (upward) or inferiorly (downward), or about a vertical axis, in other words, laterally (backward) or medially (forward), according to their position relative to the eyeball.
What is the common tendinous ring?
The tendinous ring, also known as the annulus of Zinn, is the common origin of the four rectus muscles (extraocular muscles). The tendinous ring straddles the lower, medial part of the superior orbital fissure.
Which muscles are primarily torsional muscles?
Superior and inferior oblique muscles are the primary muscles of torsion. The superior oblique creates incyclotorsion, and the inferior oblique creates excyclotorsion. As the direction of pull for both muscles forms a 51° angle (relative to the visual axis in the primary position), secondary and tertiary actions occur.
What is Intorsion?
Medical Definition of intorsion : inward rotation (as of a body part) about an axis or a fixed point especially : rotation of the eye around its anteroposterior axis so that the upper part moves toward the nose — compare extorsion.
What holds your eye in the socket?
EXTRAOCULAR MUSCLES: These muscles originate in the eye socket (orbit) and work to move the eye up, down, side to side, and rotate the eye. The superior rectus is an extraocular muscle that attaches to the top of the eye.
What is Intorsion of the eye?
Elevation and depression of the eye are termed sursumduction (supraduction) and deorsumduction (infraduction), respectively. Incycloduction (intorsion) is nasal rotation of the vertical meridian; excycloduction (extorsion) is temporal rotation of the vertical meridian.
What is abdominis or abdominus rectus?
The rectus abdominis muscle, also known as the “abdominal muscle” or simply the “abs”, is a paired muscle running vertically on each side of the anterior wall of the human abdomen, as well as that of some other mammals.
What is abdominus rectus?
rectus abdominis – slung between the ribs and the pubic bone at the front of the pelvis. When contracting, this muscle has the characteristic bumps or bulges that are commonly called ‘the six pack’. The main function of the rectus abdominis is to move the body between the ribcage and the pelvis.