Masticatory Muscles

There are five major muscles for mastication, chewing, on each side of the head. The primary muscle for elevation of the mandible is the masseter. The temporalis lying over the temporal bone acts synergistically with the masseter. Another muscle working with the masseter to elevate the mandible is the medial pterygoid. The medial pterygoid is medial to the ramus of the mandible, and so cannot be seen in Figure 17.2.

Depression of the mandible is greatly assisted by gravity and there is only one major pair of muscles involved. These muscles are the lateral pterygoids. They are hidden by the surface muscles in Figure 17.2.

The final set of muscles involved in mastication are the buccinators. These muscles form the cheeks, and function to push food between the teeth for chewing. The buccinator is barely visible in Figure 17.2, deep to the masseter and zygomaticus.

Exercise 17.5

Closely examine the models of the human head. Be able to correctly identify the muscles which have been covered in this chapter.

Sternothyoid

Thyrohyoid

Masseter

Sternothyoid

Thyrohyoid

Masseter

Sternoldomastoid Phtot Humans

Sternomastoid

Digastric Mylohyoid

Sternohyoid

Sternomastoid

Digastric Mylohyoid

Sternohyoid

Depressor Labii Inferioris
Figure 17.2 Muscles of the Face

Buccinator Depressor labii inferioris Frontalis Galea aponeurotic┬╗ Levator labii superioris Masseter Occipitalis Orbicularis oculi Orbicularis oris Platysma Temporalis Triangularis Zygomatics

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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