Intramuscular & Extraocular Muscles Quiz

The origin of the 4 recti muscles is the annulus of Zinn.

The superior oblique muscle originates from the orbital apex, specifically the lesser wing of the sphenoid bone. This muscle does not originate from the sclera or the anterior aspects of the bony orbit.

All 6 EOMS attach to the sclera

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The correct answer is CN VI, Abduction. The lateral rectus muscle is responsible for the movement of the eye called abduction, which is the movement of the eye away from the midline of the body. CN VI, also known as the abducens nerve, innervates the lateral rectus muscle and controls its contraction. This allows the eye to move laterally, away from the nose.

Sherrington's law applies to Ductions (antagonistic muscles). This law states that when one muscle is activated, its antagonist muscle is inhibited, allowing for smooth and coordinated movement. This law helps to explain how muscles work together to produce controlled and balanced movements.

The origin of the inferior oblique muscle is the anterior aspects of the bony orbit, specifically the medial wall close to the nasolacrimal canal. The annulus of Zinn and the sclera are not the origins of the inferior oblique muscle.

When the eye is adducted, it means that it is turned inward towards the nose. The superior oblique muscle is responsible for depressing or moving the eye downward. In this position, the other extraocular muscles (EOMs) that control eye movement do not contribute to the downward movement of the eye. Therefore, it can be concluded that if the eye is adducted, the superior oblique is the only EOM that depresses the eye.

Hering's law applies to vergence movements of yoked muscles. This law states that when the eyes converge or diverge to focus on a near or far object, there is an equal and opposite movement of the two eyes. This ensures that the eyes move in a coordinated manner and maintain binocular vision. Sherrington's law refers to the reciprocal innervation of agonist and antagonist muscles, while Harrington's law is not a recognized law in relation to vergence movements.

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Hering's law applies to vergence movements of yoked muscles. This law states that when both eyes move inward or outward to focus on an object, the muscles controlling the movement of the eyes work in a coordinated manner. The law explains that when the eyes converge (move inward), the medial rectus muscles contract, while the lateral rectus muscles relax. Conversely, when the eyes diverge (move outward), the lateral rectus muscles contract, while the medial rectus muscles relax. This coordination ensures that both eyes are aligned and focused on the same object.

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The medial rectus muscle is responsible for adduction, which is the movement of the eye towards the midline. CN III, also known as the oculomotor nerve, innervates the medial rectus muscle and controls its movement. This nerve supplies motor fibers to the muscle, allowing it to contract and move the eye medially.

The correct answer is CN III, Elevation, Abduction, and Extorsion. CN III refers to the oculomotor nerve, which innervates the inferior oblique muscle. Elevation refers to the upward movement of the eye, which is one of the actions performed by the inferior oblique. Abduction refers to the outward movement of the eye, another action performed by the inferior oblique. Extorsion refers to the outward rotation of the eye, which is also a function of the inferior oblique muscle.

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When the eye is adducted about 67 degrees, the only action of the vertical recti EOMs (SR and IR) is torsion. Torsion refers to the rotation of the eye around its visual axis. In this case, the vertical recti muscles are responsible for rotating the eye inwards or outwards, causing torsional movement. The other actions mentioned, such as elevation and depression, are not applicable in this specific scenario.

The inferior rectus muscle is responsible for certain movements of the eye. It is involved in adduction, which refers to the movement of the eye towards the midline. It is innervated by cranial nerve III (CN III), also known as the oculomotor nerve, which controls the movement of several eye muscles. The muscle also contributes to depression, which is the downward movement of the eye. However, extorsion, which refers to the rotation of the top of the eye away from the midline, is not applicable to the inferior rectus muscle.

The superior oblique muscle is innervated by cranial nerve IV, also known as the trochlear nerve. It is responsible for the movements of abduction (moving the eye away from the midline), depression (moving the eye downward), and intorsion (rotating the top of the eye inward). Therefore, the correct answer includes CN IV, abduction, depression, and intorsion.

The muscles used in this scenario are the Right Superior Oblique (RSO) and the Left Inferior Rectus (LIR).

The ciliary muscle and iris are both intraocular muscles. The ciliary muscle is responsible for controlling the shape of the lens, which allows the eye to focus on objects at different distances. The iris, on the other hand, controls the size of the pupil, regulating the amount of light that enters the eye. Both of these muscles are located within the eye itself and play important roles in vision. The tarsal muscle, on the other hand, is not an intraocular muscle, as it is located in the eyelid and is involved in blinking and opening/closing the eye.

The correct answer is RIR+RSO and LIR+LSO. These muscle combinations indicate the use of the Right Internal Rotators (RIR) and Right Superior Oblique (RSO) muscles, as well as the Left Internal Rotators (LIR) and Left Superior Oblique (LSO) muscles. These muscles are likely being used in some kind of physical activity or exercise.

The primary gaze is described by the superior (and inferior) oblique forming a 54 degree angle with the visual axis and the superior (and inferior) rectus forming a 23 degree angle with the visual axis.

The muscles involved in this question are the Left Serratus Anterior (LSO) and the Right Internal Rotators (RIR).

The superior rectus muscle is responsible for elevation, adduction, and intorsion of the eye. It is innervated by the oculomotor nerve (CN III). Adduction refers to the movement of the eye towards the midline, elevation refers to the upward movement of the eye, and intorsion refers to the inward rotation of the eye. Therefore, all of the given options apply to the superior rectus muscle.

Extraocular muscles:
 MR, LR, SR, IR, SO, IO
 Levator palpebrae superioris
 Tarsal muscles (or Müller’s muscle)

Coordinated binocular movement refers to the synchronized movement of both eyes to maintain binocular vision. Vergences are the inward and outward movements of the eyes to focus on objects at different distances. Gazes are the directed eye movements towards specific targets. Versions are the coordinated movements of both eyes in the same direction. All of these factors contribute to coordinated binocular movement.

The correct answer is LSR+LIO, RSR+RIO. This answer suggests that multiple muscles are involved in the given scenario. The LSR (Lateral Sphincter of the Rectum) and LIO (Internal Anal Sphincter) muscles are involved on the left side, while the RSR (Right Sphincter of the Rectum) and RIO (Internal Anal Sphincter) muscles are involved on the right side. This combination of muscles working together helps in various functions related to the rectum and anal sphincter control.

The correct answer is LMR, RLR.

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The correct answer is RSR, LIO. This means that the muscles involved in the given situation are the Right Superior Rectus (RSR) and the Left Inferior Oblique (LIO).

The muscles involved in this question are the Right Infraspinatus (RIO) and the Left Supraspinatus (LSR).