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Ch. 9 The Muscular System
Amerman - Human Anatomy & Physiology 2nd Edition
Amerman2nd EditionHuman Anatomy & PhysiologyISBN: 9780136873822Not the one you use?Change textbook
All textbooksAmerman 2nd EditionCh. 9 The Muscular SystemProblem 7
Chapter 9, Problem 7

Which eye muscle passes through the trochlea and turns the eye inferiorly and laterally?
a. Lateral rectus muscle
b. Inferior rectus muscle
c. Inferior oblique muscle
d. Superior oblique muscle

Verified step by step guidance
1
Understand the anatomy of the eye muscles: The eye has six extraocular muscles responsible for its movement. These include the lateral rectus, medial rectus, superior rectus, inferior rectus, superior oblique, and inferior oblique muscles.
Learn the function of the superior oblique muscle: The superior oblique muscle is unique because it passes through a pulley-like structure called the trochlea. This muscle helps in moving the eye inferiorly (downward) and laterally (outward).
Identify the trochlea: The trochlea is a fibrous loop located in the upper medial part of the orbit. The superior oblique muscle passes through this structure, which changes the direction of its pull.
Compare the functions of the listed muscles: The lateral rectus moves the eye laterally, the inferior rectus moves the eye inferiorly, the inferior oblique moves the eye superiorly and laterally, and the superior oblique moves the eye inferiorly and laterally.
Conclude based on the information: The muscle that passes through the trochlea and turns the eye inferiorly and laterally is the superior oblique muscle.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Trochlea

The trochlea is a fibrous ring located in the orbit of the eye that acts as a pulley for the superior oblique muscle. This structure allows the muscle to change direction as it contracts, facilitating eye movement. Understanding the role of the trochlea is essential for identifying which muscles are involved in specific eye movements.

Eye Muscles

The eye is controlled by six extraocular muscles that enable various movements, including elevation, depression, adduction, and abduction. These muscles include the superior and inferior rectus, lateral and medial rectus, and the superior and inferior oblique muscles. Each muscle has a specific function and direction of movement, which is crucial for answering questions about eye muscle actions.
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Inferior Oblique Muscle

The inferior oblique muscle is one of the extraocular muscles responsible for eye movement. It primarily functions to elevate the eye and turn it laterally. This muscle passes through the trochlea and is essential for understanding how the eye can move in different directions, particularly inferiorly and laterally, as mentioned in the question.
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Related Practice
Textbook Question

Mr. Bell presents with the inability to move certain muscles on one side of his face. You ask him to make various facial expressions and find that on his right side he is unable to purse his lips, pull in his cheeks, elevate his upper lip, and smirk. What muscles is Mr. Bell unable to contract?

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Textbook Question

Which of the erector spinae muscles is most lateral to the vertebral column?

a. Spinalis muscle

b. Iliocostalis muscle

c. Semispinalis muscle

d. Longissimus muscle

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Textbook Question

Mark the following statements as true or false. If the statement is false, correct it to make a true statement.

The buccinator muscle pulls the cheeks in, producing sucking movements.

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Textbook Question

The thick, bandlike muscle of mastication that covers much of the ramus of the mandible is the:

a. masseter muscle.

b. temporalis muscle.

c. lateral pterygoid muscle.

d. risorius muscle.

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The temporalis and occipitalis muscles are attached to each other by the epicranial aponeurosis.

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Mark the following statements as true or false. If the statement is false, correct it to make a true statement.

The orbicularis oris muscle is located around the eye.

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