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Ch. 10 The Muscular System
Marieb - Human Anatomy & Physiology 11th Edition
Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034Not the one you use?Change textbook
Chapter 10, Problem 6

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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1
Step 1: Understand the function of each muscle listed in the options. The buccinator muscles primarily assist in manipulating food within the mouth but do not protract the mandible or produce grinding movements.
Step 2: Recognize that the masseter muscles are powerful elevators of the mandible, mainly responsible for closing the jaw, not for protraction or side-to-side movements.
Step 3: Know that the temporalis muscles elevate and retract the mandible, meaning they pull the jaw backward rather than forward or side to side.
Step 4: Identify that the pterygoid muscles, specifically the lateral pterygoid, are responsible for protracting the mandible (moving it forward) and producing side-to-side grinding movements during chewing.
Step 5: Conclude that the correct muscles involved in protraction and side-to-side grinding of the mandible are the pterygoids.

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Key Concepts

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

Muscles of Mastication

These are the primary muscles responsible for chewing movements, including the masseter, temporalis, medial pterygoid, and lateral pterygoid. Each muscle contributes to specific jaw actions such as elevation, protraction, retraction, and lateral movements.
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Mandible Protraction and Grinding Movements

Protraction refers to moving the mandible forward, while side-to-side grinding involves lateral movements essential for chewing. The lateral and medial pterygoid muscles mainly facilitate these actions, enabling efficient breakdown of food.
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Function of the Pterygoid Muscles

The lateral pterygoid muscle protracts the mandible and moves it side to side, while the medial pterygoid assists in elevation and grinding. Together, they coordinate to produce the complex jaw movements needed for mastication.
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