Musculature involved in mastication. Importance. Pathologies

Mastication is the process by which food is crushed and mixed with saliva so that it can be easily swallowed and digested. This process involves several muscle groups working together to perform the action of chewing.

The muscles involved in mastication can be divided into three categories: facial muscles, neck muscles and chest muscles.

The facial muscle is the most important of the three muscle groups involved in chewing. This includes the muscles that control the movements of the jaw, such as the masseter, temporalis and pterygoid muscles. These muscles are responsible for pressing and crushing food between the teeth, as well as closing and opening the mouth.

The neck muscles, which include the sternocleidomastoid and trapezius muscles, contribute to the upward and downward movement of the mandible. They are also involved in head and neck tilting movements, which help position food in the mouth for chewing.

The muscles of the chest, including the diaphragm and intercostal muscles, help with breathing and moving food during chewing and swallowing.

Chewing is an essential process for digesting food and for the overall health of the body. It is important to keep the muscles involved in mastication healthy by eating a balanced diet and exercising regularly.

Pathologies

• Temporomandibular dysfunction

Temporomandibular dysfunction (TMD) is a common condition affecting the temporomandibular joint (TMJ) and the muscles that control jaw movements. Symptoms of TMD can include headaches, facial pain, ear pain and difficulty opening the mouth. TMD can be caused by a variety of factors, such as stress, harmful habits (such as nail chewing or gum chewing), or trauma to the head and neck.

• Myasthenia gravis is an autoimmune condition that affects the ability of muscles to relax after contraction. It can cause muscle weakness and fatigue, including in the muscles involved in chewing.

• Amyotrophic lateral sclerosis (ALS) is a progressive neuromuscular disease that affects the muscles that control jaw movements. It can cause difficulty chewing and swallowing, as well as muscle weakness and fatigue.

• Muscular dystrophy is a series of genetic diseases that affect the normal development and function of muscles. It can cause muscle weakness and fatigue, including in the muscles involved in chewing.

It is important to identify and treat pathologies that affect the muscles involved in mastication, as they can have a negative impact on digestion and the overall health of the body. Treatment may include physical therapies, medication and surgery depending on the specific cause of the pathology.

Mastication is a physiological process designed to break down food that has entered the oral cavity.

The dental units help, through their cuspidal morphology, to perform this function, but the motor, which gives the teeth the direction of movement, is the facial muscles.

Each muscle involved in the chewing process is paired, giving the movement symmetry and consistency.

There are four muscles involved in lifting and propelling the mandible in mastication and they are located and inserted in accordance with the movements performed:

• Masseter

• Temporal

• Pterygoid internal (medial)

• External pterygoid (lateral)

The mandibular descending muscles are represented by the mylohyoid, geniohyoid and digastric.

At rest, the muscles are in a slight tonic contraction designed to counteract the gravitational pull that would lower the mandible.

The muscles have the same embryonic origin, are designed to mobilize the temporomandibular joint and are traversed by the same vessels and nerves.

Their purpose is clearly defined, to mobilize the mandible in order to grind food once it has reached the oral cavity.

The fascicles of the muscles are horizontal, vertical or oblique. They form a true anchoring system for the mandible. As a result of contractions, stretches and muscle relaxations, we obtain movements of closing, opening or laterality to the right or left.

Types of masticators

Each person is characterized by a certain arrangement of teeth on the arches and by different muscular forces, which imprint a chewing pattern.

Thus, we have 3 categories:

• Chopper type: this is the patient who uses large, vertical movements during chewing. The teeth have pronounced cusps and deep pits, without wear marks.

• Scrubbing type: the patient shows horizontal chewing with predominantly lateral movements. The teeth are abraded, ground, with an almost smooth relief. This type of mastication is unfavorable because it causes wear of the teeth, which over time will either become sensitive by exposing the dentinal canaliculi or will perform inefficient mastication, leading to problems in the entire digestive system.

• Mixed type: this is the ideal situation and the one most patient have.

Pathologies with muscular origins

Muscles are not always in optimal working order.

Sometimes, either due to developmental abnormalities or inflammation or infection spread to this level, muscle fibers suffer, functional processes will be disrupted and in some cases pain may occur.

It is worth noting that stress and vicious habits can cause real damage to muscles.

The most common conditions are the following:

• Trismus: the muscles contract involuntarily due to spasms. This leads to an inability to open the mouth fully and pain that can radiate to the entire cephalic segment.

• Muscle pain from bruxism: bruxism is the movement of the teeth rubbing against each other, especially at night. Muscle fibers are overstrained and muscle fatigue occurs. The entire massaging system is affected, including the temporomandibular joint.

• Muscle hypertrophy: is an increase in the volume of a muscle. If it is unilateral, the position of the mouth will be deviated. It is often not accompanied by pain.

• Myositis: is inflammation of muscle fibers. In chronic forms, the muscle tissue is gradually replaced by fibrous, immobile tissue, incapable of supporting the movements of the jaw and muscle atrophy occurs.

There are particular situations where overflowing, incorrectly shaped or insufficiently finished fillings cause muscle pain over time.

In case of painful symptoms, whether diffuse, localized, associated or not with certain activities, the patient should go to the dentist for a specialist consultation.

If not identified in time, muscle pain causes irreparable changes in the joints, migraines and irritability.