What is the primary function of the superior rectus?
What is the primary function of the superior rectus?
It is one of the extraocular muscles. It is innervated by the superior division of the oculomotor nerve (Cranial Nerve III). In the primary position (looking straight ahead), the superior rectus muscle’s primary function is elevation, although it also contributes to intorsion and adduction.
What is the primary action of the superior oblique?
The superior oblique muscle’s primary action is eye intorsion, with secondary and tertiary actions being eye depression and abduction, respectively.
What does the superior rectus muscle control?
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.
What is the primary function of the medial rectus muscle quizlet?
the medial rectus muscle works to keep the pupil closer to the midline of the body. It helps move the eye up and down and from side to side. It is one of the extraocular muscles.
What nerve controls superior rectus?
The superior rectus is innervated by the superior division of the oculomotor nerve, which enters the muscle on its inferior face. Branches pass either through the muscle or around it to innervate the levator.
What eye movement does the inferior rectus cause?
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.
What eye movement is caused by the superior rectus?
The superior rectus and inferior oblique muscles working together pull the eye upward without rotating the eye. To depress the eye while looking straight ahead, the inferior rectus and superior oblique contract together as the superior rectus and inferior oblique relax.
What causes superior rectus palsy?
Conclusion Isolated superior rectus palsy may be caused by a contralateral midbrain lesion that selectively involves crossing superior rectus nerve fibers.
What is the action of the medial rectus?
Its function is to bring the pupil closer to the midline of the body. It is tested clinically by asking the patient to look medially. The four Recti arise from a fibrous ring (annulus tendineus communis) which surrounds the upper, medial, and lower margins of the optic foramen and encircles the optic nerve.
What is the function of the lens quizlet?
What is the function of the lens? The lens enables the changing of focus. The lens can alter its refractive power by changing its shape, a process called accommodation.
What is the function of the lateral rectus muscle?
Description: The lateral rectus muscle is a muscle in the orbit. It is one of six extraocular muscles that control the movements of the eye (abduction in this case) and the only muscle innervated by the abducens nerve, cranial nerve VI. Its function is to bring the pupil away from the midline of the body.
Which is the secondary action of the rectus muscles?
The secondary action of vertical rectus muscles is torsion. The superior rectus is an incyclotorter, and the inferior rectus is an excyclotorter. The tertiary action of both muscles is adduction. Superior and inferior oblique muscles are the primary muscles of torsion.
What are the primary actions of the inferior recti?
The inferior and superior recti have primary actions of depression and elevation, respectively. Due to their oblique insertions on the globe of 23 degrees, they also have secondary actions of excyclo and incyclo rotation, and a tertiary action of adduction.
Why does the superior rectus contract with the inferior oblique?
That’s because superior rectus usually contracts together with the inferior oblique muscle, whose fibers and pull are oriented in a way to oppose the adduction and internal rotation produced by the superior rectus and decrease them to a minimum. Thus, the end result is elevation of the eyeball.
Which is the primary action of an extraocular muscle?
action, primary. Term referring to the greatest effect of an extraocular muscle in one plane. The other actions are called the subsidiary or secondary and tertiary actions. The primary action of the inferior rectus is depression; of the superior rectus, elevation; of the inferior oblique, extorsion; and of the superior oblique, intorsion.
The secondary action of vertical rectus muscles is torsion. The superior rectus is an incyclotorter, and the inferior rectus is an excyclotorter. The tertiary action of both muscles is adduction. Superior and inferior oblique muscles are the primary muscles of torsion.
How is the superior rectus muscle of the eye stretched?
The superior rectus muscle of the eye. The superior division of the oculomotor nerve goes principally to the superior rectus muscle of the eye. This nerve may be stretched by mobilizing the superior aspect of the eyeball in an essentially caudad direction, during the cranial expansion phase.
That’s because superior rectus usually contracts together with the inferior oblique muscle, whose fibers and pull are oriented in a way to oppose the adduction and internal rotation produced by the superior rectus and decrease them to a minimum. Thus, the end result is elevation of the eyeball.
How are the lateral and superior rectus muscles innervated?
The lateral rectus muscle is innervated by the abducens nerve (6th cranial nerve), while the superior oblique muscle is innervated by the trochlear nerve (4th cranial nerve). The concerted action of pairs of extraocular muscles is required to produce the perception of single vision.