What nerve Innervates the rectus muscles?
The abducens nerve (cranial nerve VI) exits the brainstem from the pons-medullary junction and innervates the lateral rectus muscle.
What cranial nerve controls the inferior rectus eye muscle?
The inferior rectus is innervated by the inferior division of cranial nerve III, the oculomotor nerve, which enters the muscle on its superior surface.
How do you test for inferior rectus muscle?
To test the inferior rectus from the superior oblique, the clinician asks the patient to first look out (or lateral) to orient the visual gaze axis perpendicular to the superior oblique muscle fiber direction, then down.
What is the action of the inferior rectus muscle?
The medial rectus adducts (turns in) the eye, the inferior rectus depresses the eye, the superior rectus elevates the eye, and the inferior oblique abducts, elevates, and extorts (rotates out) the eye. Cranial nerve III also innervates the levator muscle, which is responsible for lid elevation.
Why is lateral rectus called muscle of divorce?
The contraction of the lateral rectus muscle rotates the eye ball sideways (laterally). During the period when the name of nerves were coined, lover’s used to communicate by indirect eye to eye contact by this very movement.
What does inferior muscle mean?
A muscle with origin from the inferior part of the tendinous ring, with insertion into the sclera of the eye, with nerve supply from the oculomotor nerve, and whose action directs the pupil downward and medialward.
Where is the left inferior rectus muscle?
The inferior rectus muscle originates from the common tendinous ring, and goes on to attach at the lower anterior surface of the eyeball. The primary action of the inferior rectus is depression of the eyeball….Inferior rectus muscle.
| Origin | Common tendinous ring (Annulus of Zinn) |
|---|---|
| Blood supply | Ophthalmic artery, infraorbital artery |
What does inferior rectus do?
The inferior rectus has a primary action of depressing the eye, causing the cornea and pupil to move inferiorly. The inferior rectus originates from the Annulus of Zinn and courses anteriorly and laterally along the orbital floor, making an angle of 23 degrees with the visual axis.
How do you isolate inferior rectus?
The lateral and medial rectus muscles are tested by asking the patient to look to the right then to the left. The actions of the superior and inferior rectus muscles are isolated by testing them when the optic axis is aligned along the orbital axis, (requiring the patient to look laterally) one eyeball at a time.
What happens when inferior rectus contracts?
To depress the eye while looking straight ahead, the inferior rectus and superior oblique contract together as the superior rectus and inferior oblique relax. The inferior rectus and superior oblique working together pull the eye downward without rotating the eye.
What is the action of the medial rectus muscle?
The medial rectus is an adductor, and functions along with the lateral rectus which abducts the eye. These two muscles allow the eyes to move from side to side. With head facing straight and the eyes facing straight ahead, the eyes are said to be in primary gaze.
What kind of muscle is the inferior rectus?
Key facts about the inferior rectus muscle Origin Common tendinous ring (Annulus of Zinn) Insertion Anterior half of eyeball (posterior to . Action Depresses, adducts, externally rotates e Innervation Oculomotor nerve (CN III) Blood supply Ophthalmic artery, infraorbital artery
What kind of nerve innervates medial rectus muscle?
The oculomotor nerve innervates the medial rectus muscle (adductor of the eye), superior rectus and inferior oblique muscles (elevators of the eye), and inferior rectus muscle (depressor of the eye). The trochlear nerve innervates the superior oblique muscle, which is responsible for the downward gaze, especially during adduction.
Where does the innervation of the rectus abdominis take place?
In addition small terminal branches of the lower three posterior intercostal arteries, subcostal and deep circumflex artery also provide some contribution. The rectus abdominius muscle is innervated by the thoracoabdominal nerves, which enter the rectus sheath by piercing its anterior surface.
Where does the inferior rectus enter the sclera?
The inferior rectus muscle passes along the floor of the orbit superior to the infraorbital canal, which houses the infraorbital artery. As it inserts onto the anteromedial part of the sclera, the inferior rectus muscle is covered by the inferior oblique muscle.
