Muscles of Mastication: Everything You Need to Know

Chewing may seem like a fairly simple process, but behind every bite is a fascinating interplay of powerful muscles working like a team. The Muscles of Mastication are a vital group of muscles that enable the movements of the jaw, thus playing a key role in eating, speaking, and even facial expressions. 

This blog explores these muscles in detail, outlining how they work, their anatomy, and their significance in daily functions. So, wait no more and sink your teeth into this comprehensive overview of one of the most essential parts of the human experience!

Table of Contents 

1) What are Muscles of Mastication? 

2) The Primary Muscles of Mastication 

3) The Accessory Muscles of Mastication 

4) Is the Buccinator a Muscle of Mastication? 

5) How do You Treat Muscle Mastication Pain?

6) Conclusion 

What are Muscles of Mastication? 

The Muscles of Mastication is a group of four powerful muscles. They work together to control the movement of the Mandible (lower jaw) during chewing. These muscles are basically responsible for all the complex grinding and movements that break down food into smaller and more manageable pieces. This process makes it easier to swallow and digest. 

These muscles are important for proper oral function. It plays a crucial role in the digestive process. They are always in sync, each of them contributing to specific aspects of chewing motion. The precise interplay of these Muscles enables food's complex and efficient breakdown.

 

 

The Primary Muscles of Mastication 

Masseter, temporalis, lateral pterygoid and medial pterygoid are the Primary Muscles of Mastication. Let's explore the individual roles they play in the overall digestive process:

a) Masseter Muscle 

The masseter muscle is a powerful, thick, rectangular muscle. It is located on the sides of the face. It elevates the Mandible (lower jaw) and provides the main force for closing the jaw. It is one of the four Muscles of Mastication, and is responsible for chewing.

The masseter muscle originates at the Zygomatic Arch which is the bony ridge below the eye. It inserts into the angle and lateral surface of the mandibular ramus (the vertical part of the lower jawbone). It consists of two distinct parts: 

a) Superficial part

b) Deep part

Here are some important points to remember:

a) The masseter muscle is innervated by the masseteric nerve, a branch of the mandibular division of the trigeminal nerve (Cranial Nerve V3).

b) This nerve transmits signals from the brain to the muscle, controlling its contractions and relaxation.

c) Dysfunction in the masseter muscle can impair chewing ability.

d) Issues with this muscle may also contribute to temporomandibular joint (TMJ) disorders.

Common issues include the following: 

a) Masseter Muscle Hypertrophy: Excessive growth of the masseter muscle can cause a square-shaped face appearance and contribute to TMJ pain and dysfunction. 

b) Masseter Muscle Atrophy: Wasting or shrinking the masseter muscle can weaken the jaw-closing ability and lead to difficulty chewing. 

c) Masseter Muscle Spasm: Involuntary masseter muscle contraction can cause pain, lockjaw, and difficulty opening the mouth. 

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b) Temporalis Muscle 

The temporalis muscle is a large, fan-shaped muscle found on the sides of the skull. It extends from the temporal bone, located on either side of the head. It is one of the four Muscles of Mastication, responsible for chewing.
 

The temporalis muscle originates from the Temporal Fascia, a thin connective tissue covering the temporal bone. It is composed of two main parts that are as follows: 

1) Superior part

2) Inferior part

The temporalis muscle is crucial for chewing as it raises the mandible and helps with the jaw's grinding and crushing actions. It works with the other Muscles of Mastication to reduce food into smaller fragments. 

The temporalis muscle is innervated by the temporal branches of the Mandibular division of the Trigeminal nerve (cranial nerve V3). These nerve branches transmit signals from the brain to the muscle, controlling its contraction and relaxation. Any condition that affects the temporalis muscle can impair chewing ability and lead to Temporomandibular Joint (TMJ) disorders. Common issues include the following: 

a) Temporalis Muscle Hypertrophy: Excessive growth of the temporalis muscle can cause a bulging or fullness on the sides of the head and contribute to TMJ pain and dysfunction. 

b) Temporalis Muscle Atrophy: Wasting or shrinking the temporalis muscle can weaken the jaw-closing ability and lead to difficulty chewing. 

c) Temporalis Muscle Spasm: Involuntary contraction of the temporalis muscle can cause pain, headaches, and difficulty opening the mouth. 

c) Lateral Pterygoid Muscle  

This is a two-headed muscle located deep within the infratemporal fossa, which is a complex area situated at the base of the skull. It is also one of the four Muscles of Mastication.

The lateral pterygoid muscle consists of two distinct heads, that are as follows: 

1) Superior head

2) Inferior head

The lateral pterygoid muscle plays a versatile role in chewing, contributing to various mandibular movements. Its primary functions include the following: 

a)  Protrusion: It protracts the mandible, moving it forward and allowing incisor biting. 

b) Lateral Excursion: It moves the mandible laterally (side-to-side), enabling grinding and crushing motions. 

c) Depression: It assists in depressing the Mandible, contributing to jaw opening. 

Here are some points to remember:

a) The lateral pterygoid muscle is innervated by the lateral pterygoid nerve.

b) The lateral pterygoid nerve is a branch of the mandibular division of the trigeminal nerve (Cranial Nerve V3).

c) This nerve transmits signals from the brain to the muscle.

d) The signals regulate the contraction and relaxation of the lateral pterygoid muscle.

Common issues include the following: 

a) Lateral Pterygoid Muscle Spasm: Involuntary muscle contraction causes pain, difficulty opening the mouth, and a clicking or popping sensation in the TMJ. 

b) Lateral Pterygoid Muscle Injury: Damage to the muscle can result from trauma, overuse, or inflammation, leading to pain, chewing difficulties, and TMJ dysfunction. 

c) Temporomandibular Disorders: TMJ conditions can involve the lateral pterygoid muscle, contributing to pain, clicking or popping sounds, and limitations in jaw movement. 

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d) Medial Pterygoid Muscle 

The medial pterygoid muscle is a thick, strap-like muscle located deep within the Infratemporal Fossa of the skull.

This muscle originates from the medial pterygoid plate (a bony projection of the sphenoid bone) and inserts into the Angle of the Mandible (lower jaw). It's composed of two distinct parts: 

a) Superficial part

b) Deep Part

The medial pterygoid nerve is a branch of the mandibular division of the trigeminal nerve that innervates the medial pterygoid muscle. It's additionally known as the Cranial nerve V3. It conveys signals from the brain to the muscle, regulating contraction and relaxation. Any issue impacting the medial pterygoid muscle can hinder chewing proficiency and result in temporomandibular joint (TMJ) disorders. Common issues include the following:  

a) Medial Pterygoid Muscle Hypertrophy: Excessive growth of the medial pterygoid muscle can cause a bulge or fullness on the sides of the face and contribute to TMJ pain and dysfunction. 

b) Medial Pterygoid Muscle Atrophy: Wasting or shrinking of the medial pterygoid muscle can weaken the jaw-closing ability and lead to difficulty chewing. 

c) Medial Pterygoid Muscle Spasm: Involuntary contraction of the medial pterygoid muscle can cause pain, difficulty opening the mouth, and a  popping or clicking sensation in the TMJ. 

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The Accessory Muscles of Mastication 

There are some more muscles which help in the Mastication process. These muscles are listed below: 

a) Buccinator  

The buccinator muscle is a quadrilateral thin muscle that forms the lateral wall of the oral cavity and the cheek. The buccinator muscle originates from the upper jawbone and the Ramus of the lower jawbone. It further inserts into the Modiolus, a structure at the corner of the mouth. It plays a variety of roles in facial movements and chewing. Here's how:

The buccinator muscle originates from the Maxilla (upper jawbone) and the Ramus of the Mandible (lower jawbone). It further inserts into the Modiolus, a fibrous structure at the corner of the mouth. It plays a variety of roles in facial movements and chewing. Here's how: 

1) Chewing

2) Facial expressions

3) Swallowing

The buccinator muscle is stimulated by the buccal nerve, a branch of the trigeminal nerve's mandibular division (V3) (cranial nerve V) which helps regulate contraction and relaxation. Any condition negatively affecting the buccinator muscle can impair facial movements, chewing ability, and swallowing. Common issues include the following: 

a) Buccinator Muscle Paralysis: Damage to the buccal nerve can paralyse the buccinator muscle. This can lead to facial asymmetry, difficulty chewing, and drooling. 

b) Buccinator Muscle Spasm: Involuntary contraction of the buccinator muscle can cause pain and difficulty opening the mouth. 

c) Buccinator Muscle Hypertrophy: Excessive growth of the buccinator muscle can cause a square-shaped face appearance. 

d) Buccinator Muscle Atrophy: Wasting or shrinking of the buccinator muscle can lead to difficulty chewing and facial sagging. 

b) Suprahyoid Muscles  

The suprahyoid muscles form a group of four muscles situated above the hyoid bone in the neck. They are responsible for elevating the Hyoid bone involved in swallowing and speech. The four suprahyoid muscles include the following: 

 

a) Digastric Muscle: It is a two-bellied muscle that begins from the Mastoid process of the Temporal bone and inserts into the digastric fossa of the Mandible. It elevates the hyoid bone and helps to open the mouth. 

b) The Stylohyoid Muscle: It originates from the Temporal bone's Styloid process and ends in the greater horn of the Hyoid bone. It elevates and retracts the hyoid bone 

c) The Geniohyoid Muscle: The geniohyoid muscle originates from the Mandible's mental spine and ends in the body of the Hyoid bone. It elevates and protrudes the Hyoid bone. 

d) Mylohyoid Muscle: It is a broad, fan-shaped muscle that composes the floor of the mouth. It originates from the mylohyoid line of the Mandible and inserts into the Raphe Pterygomandibulare. It elevates and tenses the floor of the mouth. 

e) The Suprahyoid Muscles: They work together to elevate the hyoid bone, which is necessary for swallowing and speech. They also help to open the mouth and tense the floor of the mouth. 

c) Infrahyoid Muscles 

The infrahyoid muscles (or strap muscles) refer to a group of four paired muscles just below the hyoid bone in the neck. They are responsible for depressing the hyoid bone during the swallowing action and stabilising the larynx during speech. The four infrahyoid muscles are as follows: 

  

a) The sternohyoid Muscle: Originates from the Sternum (breastbone) and inserts into the Hyoid bone. It depresses the Hyoid bone. 

b) The Sternothyroid Muscle: Originates from the Sternum (breastbone) and ends in the Thyroid Cartilage of the Larynx. It depresses the Larynx. 

c) The Thyrohyoid Muscle: Originates from the Larynx's Thyroid Cartilage and inserts into the Hyoid bone. It depresses the Hyoid bone and elevates the larynx. 

d) The Omohyoid Muscle: This long, thin muscle originates from the Scapula (shoulder blade), passes over the clavicle (collarbone), and inserts into the hyoid bone. It helps to stabilise the larynx and depress the hyoid bone. 

e) The Infrahyoid Muscles: They work together to depress the hyoid bone, which is necessary for swallowing. They also help to stabilise the larynx during speech. 

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Is the Buccinator a Muscle of Mastication?

Although the buccinator is not considered among the main Muscles of Mastication, it serves an essential supportive function in the process. Situated in the cheek, this muscle aids by pressing the cheeks against the teeth, ensuring that the food is held properly while chewing.

How do You Treat Muscle Mastication Pain?

Treating Muscle Mastication pain involves a combination of self-care practices, medical treatments, and lifestyle adjustments. You must avoid any activity that strains the jaw, such as chewing gum. Over-the-counter pain relievers like ibuprofen or acetaminophen can also help manage muscle pain.

Conclusion 

 the Muscles of Mastication are vital for everyday functions such as chewing, speaking, and maintaining jaw stability. Understanding their anatomy and roles highlights their importance in oral health and overall physical health. As detailed in this blog, these muscles work tirelessly behind the scenes, from powerful movements to comp-lex coordination, offering deep insight into the marvels of human anatomy.

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