Muscle which makes the angle of 51° to optical axis
**Core Concept**
The question is testing knowledge of the extraocular muscles responsible for eye movements. The angle of 51° to the optical axis refers to the position of a specific muscle that contributes to the binocular field of vision.
**Why the Correct Answer is Right**
The muscle responsible for this angle is the **Lateral Rectus**. This muscle, along with the other extraocular muscles, works to rotate the eyeball and maintain the binocular field of vision. The Lateral Rectus specifically abducts the eyeball, moving it away from the midline of the face. This action is crucial for maintaining the 51° angle to the optical axis, allowing for smooth and coordinated eye movements.
**Why Each Wrong Option is Incorrect**
**Option A:** The **Medial Rectus** muscle is responsible for adduction, moving the eyeball towards the midline of the face. This action does not contribute to the 51° angle to the optical axis.
**Option B:** The **Superior Rectus** muscle primarily elevates the eyeball, and its action does not directly relate to the angle in question.
**Option C:** The **Inferior Oblique** muscle rotates the eyeball laterally and elevates it, but its action is not responsible for the 51° angle to the optical axis.
**Clinical Pearl / High-Yield Fact**
To remember the extraocular muscles and their functions, use the mnemonic "All ERs Go to Med School": **E**levate (Superior Rectus), **R**otate (Lateral and Medial Rectus), **A**bduct (Lateral Rectus), **D**uct (Medial Rectus), and **R**otate (Inferior Oblique).
**Correct Answer:** D. Lateral Rectus