Textbook Question
The chewing muscles that protract the mandible and produce side-to-side grinding movements are the
a. Buccinators
b. Masseters
c. Temporalis
d. Pterygoids
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10. Muscles
Muscle Naming
1:54 minutesProblem 8
Textbook Question
The muscle that rotates the eye medially is the
(a) Superior oblique
(b) Inferior rectus
(c) Medial rectus
(d) Lateral rectus
Verified step by step guidance1
Step 1: Understand the anatomy of the eye muscles. The eye is controlled by six extraocular muscles, each responsible for specific movements. These muscles include the superior rectus, inferior rectus, medial rectus, lateral rectus, superior oblique, and inferior oblique.
Step 2: Identify the function of each muscle. The medial rectus muscle is responsible for moving the eye medially (toward the nose). The lateral rectus moves the eye laterally (away from the nose). The superior oblique and inferior oblique muscles control rotational and diagonal movements, while the superior rectus and inferior rectus control vertical movements.
Step 3: Focus on the term 'rotates the eye medially.' Medial rotation refers to moving the eye toward the midline of the body, which is the function of the medial rectus muscle.
Step 4: Eliminate incorrect options based on their functions. For example, the lateral rectus moves the eye laterally, not medially. The superior oblique and inferior rectus muscles do not primarily rotate the eye medially.
Step 5: Conclude that the correct answer is the muscle responsible for medial rotation of the eye, which is the medial rectus.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Eye Muscle Anatomy
The eye is controlled by six extraocular muscles that facilitate its movement. These muscles include the superior oblique, inferior rectus, medial rectus, lateral rectus, superior rectus, and inferior oblique. Understanding the function and location of each muscle is crucial for identifying their roles in eye movement.
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Medial Rotation of the Eye
Medial rotation, or adduction, refers to the movement of the eye towards the midline of the body. This action is primarily performed by the medial rectus muscle, which is responsible for pulling the eye inward. Recognizing which muscle is responsible for this specific movement is essential for answering the question.
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Muscle Function and Innervation
Each extraocular muscle has a specific function and is innervated by different cranial nerves. The medial rectus muscle is innervated by the oculomotor nerve (CN III), which is vital for its contraction and subsequent eye movement. Understanding the innervation helps clarify how these muscles operate in coordination to achieve precise eye movements.
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