Anatomy and Function of the Muscles of Mastication

Introduction

The muscles of mastication play a crucial role in chewing, speaking, and facial expressions. These muscles, controlled by the mandibular branch of the trigeminal nerve (CN V3), facilitate complex jaw movements essential for daily functions.

Primary Muscles of Mastication

• Masseter: Responsible for jaw elevation and forceful closing.
• Temporalis: Aids in jaw elevation and retraction.
• Medial Pterygoid: Assists in jaw elevation and side-to-side movement.
• Lateral Pterygoid: Primarily involved in jaw depression and protrusion.

Functions and Actions

Elevation of the Mandible

Masseter, temporalis, and medial pterygoid work synergistically to close the jaw.

Depression of the Mandible

Lateral pterygoid, assisted by gravity and suprahyoid muscles, helps in jaw opening.

Protrusion and Retraction

The lateral pterygoid enables forward movement, while the temporalis supports backward movement.

Clinical Significance

Dysfunction in these muscles can lead to temporomandibular joint (TMJ) disorders, affecting chewing and speech.

Conclusion

Understanding the muscles of mastication is essential for diagnosing jaw-related conditions and optimizing treatments.