The superior oblique muscle, or obliquus oculi superior, is a fusiform muscle originating in the upper, medial side of the orbit (i.e. from beside the nose) which abducts, depresses and internally rotates the eye. It is the only extraocular muscle innervated by the trochlear nerve (the fourth cranial nerve).
Likewise, what direction does the superior oblique muscle move the eye? The trochlear nerve supplies only the superior oblique muscle, which moves the eye downwards and medially towards the nose.
In this regard, how do you test superior rectus muscle?
To test superior rectus from the inferior oblique, the clinician asks the patient to first look out (or lateral) to orient the visual gaze axis perpendicular to the inferior oblique muscle fiber direction, then up. After the inferior oblique is trapped, the only muscle that can mediate elevation is the superior rectus.
Where does the superior oblique insertion?
The superior oblique originates from the greater wing of the sphenoid bone deep in the medial side of the orbit, above the medial margin of the optic canal. The superior oblique inserts into the posterior, superior, and lateral surface of the eyeball.
Where is the inferior oblique muscle located?
The inferior oblique muscle or obliquus oculi inferior is a thin, narrow muscle placed near the anterior margin of the floor of the orbit. The inferior oblique is an extraocular muscle, and is attached to the maxillary bone (origin) and the posterior, inferior, lateral surface of the eye (insertion).
What is the shortest extraocular muscle?
Is the lateral rectus muscle horizontal or vertical?
Horizontal movements are controlled entirely by the medial and lateral rectus muscles; the medial rectus muscle is responsible for adduction, the lateral rectus muscle for abduction. Vertical movements require the coordinated action of the superior and inferior rectus muscles, as well as the oblique muscles.
What does the superior rectus muscle do?
The main actions provided by the superior rectus are elevation and adduction of the eyeball, and medial rotation of the eyeball. To obtain the upward movement, the muscle must function in synergy with the inferior oblique. The superior rectus is innervated by the superior division of the oculomotor nerve (CN III).
What does Intorsion mean?
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 are the muscles of the eye?
Eye muscle anatomy. There are six extraocular muscles that move the globe (eyeball). These muscles are named the superior rectus, inferior rectus, lateral rectus, medial rectus, superior oblique, and inferior oblique.
Which of the extraocular muscles allow you to look down and out?
When turning the eye down and in, the inferior rectus is contracting. When turning it up and in the superior rectus is contracting. Paradoxically, turning the eye up and out uses the inferior oblique muscle, and turning it down and out uses the superior oblique.
What is Intorsion of eye?
Eye Movements. 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. (See the image below.)
How do you check eye muscles?
The extraocular muscle function test is performed to evaluate any weakness, or other defect in the extraocular muscles which results in uncontrolled eye movements. The test involves moving the eyes in six different directions in space to evaluate the proper functioning of the extraocular muscles of the eyes.
What is the superior rectus?
The superior rectus muscle is a muscle in the orbit. It is one of the extraocular muscles. In the primary position (looking straight ahead), the superior rectus muscle’s primary function is elevation, although it also contributes to intorsion and adduction.
How do you test extraocular muscle function?
Check extraocular movements (eye movements) by having the patient look in all directions without moving their head and ask them if they experiences any double vision. Test smooth pursuit by having the patient follow an object moved across their full range of horizontal and vertical eye movements.
Where are the extraocular muscles located?
The Extraocular Muscles. The extraocular muscles are located within the orbit, but are extrinsic and separate from the eyeball itself. They act to control the movements of the eyeball and the superior eyelid.
Where is the medial rectus muscle located?
The medial rectus muscle is a muscle in the orbit. As with most of the muscles of the orbit, it is innervated by the inferior division of the oculomotor nerve (Cranial Nerve III). This muscle shares an origin with several other extrinsic eye muscles, the anulus tendineus, or common tendon.
What does the Trochlear nerve do?
Location and Function The trochlear nerve is also known as the fourth cranial nerve. It exits the brain on the dorsal side of the brain stem. The trochlear nerve is a motor nerve, and it controls the superior oblique muscle of the eye.