Dominic Stone
The masseter muscle is a powerful muscle in the human face and jaw that is essential for chewing. Humans have two masseter muscles, one on each side of the face, which work with other muscles to move the jaw bone and the temporomandibular joint. The masseter muscle can be easily palpated from the oral cavity along the cheek. It can become enlarged or overworked due to habits such as clenching, grinding, or chewing gum, leading to a condition called masseter hypertrophy. This condition can cause a square-angled face and psychological distress due to the change in facial appearance. Checking the masseter muscle involves understanding its positioning, function, and potential issues that can arise from overuse.
| Characteristics | Values |
|---|---|
| Number of masseter muscles | 2 |
| Muscle shape | Rectangular |
| Muscle layers | 3 |
| Muscle type | Powerful, thick, superficial, quadrangular |
| Muscle function | Elevation and protrusion of the mandible |
| Muscle origin | Zygomatic arch |
| Muscle extension | Mandibular angle |
| Muscle innervation | Mandibular division of the trigeminal nerve |
| Blood supply | Masseteric artery |
| Conditions | Temporomandibular joint dysfunction (TMD) |
| Treatments | Conservative/non-surgical therapies, surgery, liposuction |
Explore related products
What You'll Learn
Masseter muscle hypertrophy
The masseter muscle is a paired, strong, thick and rectangular muscle that is essential for adequate mastication (chewing). Humans have two masseter muscles, one on each side of the face, which help to elevate the lower jaw and assist in the forward movement of the lower jaw.
There are some common factors that can contribute to overworking the masseter muscles, such as emotional stress, chronic clenching or grinding during the day or night, and repetitive habits such as gum chewing. These habits are often unconscious, and over time, they can cause the masseter muscles to become enlarged or bulk up.
There are two approaches to treating masseter muscle hypertrophy: conservative/non-surgical therapies and surgical methods. Conservative therapies include splint therapy, which uses an oral appliance to help decrease biting forces from clenching and grinding, and behaviour therapy, which helps patients address behavioural habits that may be contributing to overworking the masseter muscles. Surgical methods include the traditional approach of surgically removing part of the masseter muscle, jawbone, or performing liposuction of the fat near the muscle. Another surgical option is botulinum toxin type A (Botox) injections directly into the muscle to help reduce muscle contractions.
Testing Muscle Atrophy: Methods and Techniques
You may want to see also
Explore related products
Masseter muscle anatomy
The masseter muscle is a paired muscle, with one masseter muscle on each side of the face. It is strong, thick, and rectangular, originating from the zygomatic arch and extending down to the mandibular angle. The masseter muscle is part of the masticatory group of muscles, which also includes the temporal muscle, lateral pterygoid muscle, and medial pterygoid muscle. These muscles work together to facilitate the process of chewing and eating.
The masseter muscle has both a superficial part and a deep part. The superficial part of the muscle lies over the deep part and originates from the maxillary process of the zygomatic bone. It then runs downward and forward to the masseteric tuberosity on the lower part of the superficial side of the ramus of the mandible. The deep part of the muscle consists of vertically directed muscle fibres that originate from the entire length of the inferior border of the zygomatic arch and insert into the upper half of the ramus of the mandible.
The masseter muscle is covered by a thin but very strong masseteric fascia on its entire superficial (or lateral) aspect. Below the zygomatic process, the duct of the parotid gland crosses the surface of the muscle. The parotid gland itself is located superficially to the masseter, towards the posterior. The medial surface of the masseter muscle is related to the ramus of the mandible, which almost completely covers its superficial surface. The medial aspect of the masseter muscle forms the lateral wall of the facial space, known as the submasseteric space.
The masseter muscle is innervated by the masseteric nerve, a special branch of the mandibular nerve. It receives its blood supply from the masseteric artery, a branch of the maxillary artery. The function of the masseter muscle is to elevate and protrude the mandible, as well as provide support to the articular capsule of the temporomandibular joint.
Bodybuilders' Muscle Loss: What, Why, and How to Prevent It
You may want to see also
Explore related products
Masseter muscle origin and insertion
The masseter muscle is a paired, strong, thick, and rectangular muscle with two divisions: a superficial and a deep part. It is one of the four muscles of the masticatory apparatus, a group of muscles used for chewing that also includes the temporal muscle, lateral pterygoid muscle, and medial pterygoid muscle. Its specific functions are elevation and protrusion of the mandible, as well as providing support to the articular capsule of the temporomandibular joint.
The masseter muscle originates from the zygomatic arch and inserts along the angle and lateral surface of the mandibular ramus. The superficial portion of the muscle originates from a thick aponeurosis on the temporal process of the zygomatic bone and the anterior two-thirds of the inferior border of the zygomatic arch. The deep portion of the masseter muscle originates from the entire surface of the zygomatic arch, with its fibres running inferiorly and inserting along the mandibular ramus superior to the masseter muscle's superior portion.
The fibres of the superficial portion pass inferior-posteriorly over the deep portion and insert onto the angle of the mandible (masseteric tubercle) and the inferior portion of the lateral surface of the mandibular ramus. The masseteric tuberosity is found on the lower part of the superficial side of the ramus of the mandible. The deep head of the muscle is partly concealed, anteriorly, by the superficial portion. Posteriorly, it is covered by the parotid gland, which surrounds the entire posterior and most of the superficial aspect of the muscle.
The masseter muscle is supplied with blood by the masseteric artery, a branch of the maxillary artery. It is innervated by the anterior division of the mandibular division (V3) of the trigeminal nerve.
Muscle Knots: How Long Can They Last?
You may want to see also
Explore related products
Masseter muscle functions
The masseter muscle is one of the four primary muscles of mastication, or chewing. Humans have two masseter muscles, one on each side of the face, which are part of a group of four pairs of muscles used for chewing. These muscles are strong, thick, and rectangular, and originate from the zygomatic arch, extending down to the mandibular angle. The masseter muscle has a superficial and a deep part.
The masseter muscle is responsible for the elevation of the mandible, or lower jaw, and some protraction. It works in conjunction with two other jaw-closing muscles, the temporalis and the medial pterygoid, to close the jaw. The contraction of the superior part of the masseter muscle moves the mandible forward (protrusion). This brings the lower front teeth in front of the upper front teeth. The masseter muscle also helps to stabilise tension in the articular capsule of the temporomandibular joint.
The intermediate and deep muscle fibres of the masseter muscle function to retract the mandible, while the superficial fibres function to protrude the mandible. The masseter muscle is innervated by the masseteric nerve, a branch of the mandibular nerve (V3) of the trigeminal nerve. The motor fibres of the masseteric nerve supply the masseter muscle, allowing it to contract and perform its primary function of elevating the mandible. The sensory fibres of the mandibular nerve provide sensation to the lower teeth, gums, and lip, as well as the skin of the chin and lower jaw.
The masseter muscle can become enlarged, or hypertrophied, in individuals who habitually clench or grind their teeth, or bruxism, and in those who chew gum. This masseteric hypertrophy is usually asymptomatic and soft, and it can be unilateral or bilateral. However, it can cause a square-angled or bottom-heavy appearance of the face, which may be undesirable and lead to psychological distress.
The Diaphragm Muscle: Locating and Understanding Its Function
You may want to see also
Explore related products
Masseter muscle conditions
The masseter muscle is one of the four pairs of muscles that enable us to chew and eat our food. It helps elevate the lower jaw and assists in the forward movement of the lower jaw.
The most common condition affecting the masseter muscle is temporomandibular joint dysfunction (TMD). TMD is a broad condition that encompasses several different types of disorders. The most common symptoms of TMD are pain in the jaw or with chewing. TMD is often self-limiting and may go away with appropriate treatment. Surgical options are not typically effective. Instead, treatment is highly individualised and may include interventions such as breaking the habit of jaw clenching, eating softer foods, and taking over-the-counter medications.
Another condition that can affect the masseter muscle is masseter muscle hypertrophy, a rare condition in which the masseter muscle is enlarged on one or both sides of the face. The exact cause of masseter muscle hypertrophy is unknown, but it is often associated with teeth grinding or clenching, gum chewing, or a preference for chewing on one side. This condition is typically asymptomatic and benign, but it can cause psychological distress due to the change in facial appearance. Treatment options for masseter muscle hypertrophy include conservative/non-surgical therapies such as splint therapy, behaviour therapy, and botulinum toxin (Botox) injections.
Other conditions that can affect the masseter muscle include:
- Submasseteric abscesses, which are relatively rare and can be confused with parotid gland infections.
- Trismus, which is a strong and persistent spasm of the masseter muscle that can interfere with the normal feeding process. It can occur when infected with the bacteria Clostridium tetani.
- Trauma to the jaw and masseter muscles, which may require a period of immobilisation and rest to allow the muscles to heal properly.
The Language of Nerves: Communicating with Muscles
You may want to see also
Frequently asked questions
The masseter muscle is one of the four muscles responsible for the action of mastication (chewing). It helps elevate the mandible, causing the mouth to close.
Humans have two masseter muscles, one on each side of the face. The masseter muscle originates from the zygomatic arch and extends down to the mandibular angle.
Masseter muscle hypertrophy refers to the enlargement of the masseter muscle. It can be caused by emotional stress, chronic clenching or grinding, repetitive habits such as gum chewing, or a preference for chewing on one side. If you suspect you have this condition, consult a medical professional.
Masseter hypertrophy is typically asymptomatic, but it can be associated with pain, clenching/grinding, and functional disorders of the jaw. It can also cause psychological distress due to the change in facial appearance, such as a square-angled or bottom-heavy jaw.
