Maximus Gage
The human face has about 20 facial muscles that enable essential functions such as chewing and making facial expressions. These muscles are located all over the face, including the ears, mouth, forehead, nose, and eyes. The jaw is formed by two bones: the mandible (lower jawbone) and the temporal bone (a bone on the side of the skull). The mandible is moved by several muscles, including the masseter, temporalis, medial pterygoid, and lateral pterygoid muscles. These muscles attach to the mandible and produce movements such as protrusion, retraction, elevation, and depression, which enable functions like chewing and grinding. Jaw alignment issues, such as asymmetry or jaws that are too large or small, can cause problems with chewing, speaking, breathing, and even sleeping.
| Characteristics | Values |
|---|---|
| Number of masseter muscles | 2 (one on each side of the jaw) |
| Shape of masseter muscle | Parallelogram/rectangular |
| Masseter muscle parts | Superficial and deep |
| Masseter muscle function | Elevates the mandible, stabilizes tension of the articular capsule of the temporomandibular joint (TMJ), and supports chewing |
| Masseter muscle nerve | Masseteric nerve, a branch of the trigeminal nerve |
| Other muscles of mastication | Temporalis, medial pterygoid, lateral pterygoid, buccinator, suprahyoid, infrahyoid |
| Jaw pain disorders | Myofascial pain, myalgia, myospasm, bruxism, temporomandibular joint (TMJ) dysfunction |
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What You'll Learn
- The jaw is formed by the mandible and temporal bone
- The masseter muscle is responsible for jaw movement
- The temporalis muscle is situated in the temporal fossa
- The pterygoid muscles are triangular and lie in the infratemporal fossa
- Jaw alignment issues can cause problems with chewing, speaking, breathing and sleeping
The jaw is formed by the mandible and temporal bone
The jaw is formed by the mandible and the temporal bone. The mandible is the largest bone in the facial skeleton and is the only movable bone in the skull, excluding the ossicles of the middle ear. The mandible is a horseshoe-shaped bone that consists of a body and two rami, connected at the angle of the mandible. The body of the mandible is the horizontal portion, with the front part giving structure to the chin. The mandible holds the lower teeth in place and is essential for chewing food.
The mandible is connected to the skull's temporal bones by the temporomandibular joints, which allow the mandible to articulate side to side, as well as forward and back, in addition to simply opening and closing. The temporomandibular joint is where the jaw attaches to the skull below the ears. This joint is formed by the articulation of the mandible with the articular tubercle of the temporal bone. The temporomandibular joint enables complex actions such as chewing, speaking, yawning, kissing, and breathing.
The masseter muscle, which is a facial muscle that plays a major role in chewing solid foods, connects to the mandible (lower jawbone) and the cheekbone. The masseter muscle is controlled by the masseteric nerve, a branch of the trigeminal nerve. It is the key muscle that elevates the jaw during chewing and is assisted by four other muscles. The masseter muscle also helps to stabilise the temporomandibular joint when clenching the teeth.
The mandible is a vital bone in terms of forensic evidence as it constantly changes throughout an individual's life. It is often used to determine the age of the deceased. The mandible is subject to various conditions and disorders, such as osteomyelitis, an irreversible infection that can cause bone disintegration and may require resection of the mandible. Temporomandibular disorders (TMDs) are a common group of conditions affecting the temporomandibular joint or surrounding muscles, causing pain or tenderness.
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The masseter muscle is responsible for jaw movement
The masseter muscle is one of the four muscles that enable mastication, or the act of chewing. It is a powerful, thick, quadrilateral muscle that connects to the mandible (lower jawbone) and the cheekbone. There are two masseter muscles in the human body, with one on each side of the jaw.
The masseter muscle is responsible for the elevation of the mandible, causing the mouth to close. It also aids in the protrusion of the mandible, allowing for the anterior motion of the jaw. This means that the masseter muscle plays a major role in chewing solid foods. When chewing, the masseter muscle is assisted by four other muscles.
The masseter muscle is controlled by the masseteric nerve, a branch of the trigeminal nerve, also known as the fifth cranial nerve. The masseter muscle receives its motor innervation from the mandibular division of the trigeminal nerve. The blood supply to the masseter muscle primarily comes from the masseteric artery, a branch of the internal maxillary artery.
The masseter muscle can be examined by having the patient clench their jaw and evaluating the volume and firmness of the muscles. The masseter muscle can become enlarged in patients who habitually clench or grind their teeth, even in those who constantly chew gum. This condition is called masseteric hypertrophy and can result in restricted movement of the jaw, pain, or headaches. Masseter hypertrophy can be treated with Botox injections or surgery.
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The temporalis muscle is situated in the temporal fossa
The jaw muscles are essential for chewing and play a major role in the chewing of solid foods. One of these muscles is the temporalis muscle, which is situated in the temporal fossa. The temporalis muscle is a thin, fan-shaped muscle that occupies most of the temporal fossa of the skull. The fossa is a broad area of attachment, and the muscle covers it with its deep surface. The temporal fossa is a depression in the skull located just above the ear and is the site of origin and insertion for several muscles, including the temporalis.
The temporalis muscle is one of the muscles of mastication (chewing). It is a broad, fan-shaped convergent muscle on each side of the head. The muscle fibres originate from the temporal fossa and the deep part of the temporal fascia, which is a fibrous connective tissue that covers, supports, and separates muscles. The origin point of the temporalis muscle spans the entire surface of the fossa below the temporal line. The muscle then passes medial to the zygomatic arch, which is the bone that forms the cheekbone.
The temporalis muscle is the strongest muscle of the temporomandibular joint (TMJ), which is the joint that connects the jaw to the skull. The main function of the temporalis muscle is to produce movements of the mandible (lower jawbone) at the TMJ, thus facilitating the act of mastication. The anterior portion of the muscle moves the mandible dorsocranially (elevation), while the posterior fibres pull the mandible backward (retrusion). These actions work in unison to facilitate the closing of the mouth and the approximation of the teeth.
The temporalis muscle is innervated by the anterior, middle, and posterior deep temporal branches of the anterior trunk of the mandibular nerve (V3). It receives its blood supply from the deep temporal branches of the maxillary artery and the middle temporal branches of the superficial temporal artery. The auriculotemporal, facial, and zygomaticotemporal nerves run across the superficial aspect of the muscle.
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The pterygoid muscles are triangular and lie in the infratemporal fossa
The jaw muscles are involved in the chewing of solid foods and the elevation of the jaw. The masseter muscle is a facial muscle that connects to the mandible (lower jawbone) and the cheekbone. There are two masseter muscles, one on each side of the jaw. The temporomandibular joint (TMJ) is where the jaw attaches to the skull below the ears.
The pterygoid muscles receive their blood supply from the branches of the maxillary artery. The maxillary artery is an important vascular structure within the infratemporal fossa, giving off numerous branches. It courses deep to or on the superficial surface of the lateral pterygoid muscle and supplies the masseter muscle. The middle meningeal artery, arising medial to the neck of the mandible, passes through a split in the auriculotemporal nerve and enters the middle cranial fossa. The inferior alveolar artery descends through the infratemporal fossa alongside the inferior alveolar nerve, supplying the mandibular teeth, mandible, and surrounding regions.
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Jaw alignment issues can cause problems with chewing, speaking, breathing and sleeping
The jaw is controlled by several muscles, including the masseter muscle, which plays a major role in chewing solid foods. The masseter muscle is shaped like a parallelogram and connects to the mandible (lower jawbone) and the cheekbone. There are two masseter muscles, one on each side of the jaw.
Jaw alignment issues can cause problems with chewing, speaking, breathing, and sleeping. A crooked jaw can cause difficulty in chewing, speaking, and drinking. More severe cases can also cause problems with breathing during sleep and impact physical appearance, damage teeth and gums, and affect mental health. Jaw alignment issues can also cause snoring and other breathing difficulties during sleep. For example, sleeping on one's stomach can put significant pressure on the neck and jaw, leading to misalignment and restricted airflow. Similarly, back sleeping can cause the tongue and soft tissues to collapse into the throat, obstructing the airway.
There are several ways to address jaw alignment issues and their associated problems. For those who sleep on their side, using a supportive pillow can help keep the head and neck in line with the spine, reducing pressure on the jaw and the risk of misalignment. Back sleepers can try using a slightly raised pillow to prevent the airway from collapsing. Switching to sleeping on one's back or side, or using a very thin pillow, can help those who sleep on their stomachs.
In addition to adjusting sleep posture, other treatments for jaw alignment issues include orthodontics, surgery, and symptom management. Eating soft foods can help with any associated pain, and over-the-counter medications such as ibuprofen or aspirin can reduce inflammation and pain. Relaxation methods such as meditation and mindfulness can also help ease muscle pain and tension in the jaw.
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Frequently asked questions
The jaw muscles are located in the face, with the major muscles being the masseter, temporalis, and pterygoid muscles. The masseter muscle is in the cheek area, while the temporalis muscle is in the temporal fossa. The pterygoid muscles lie in the infratemporal fossa.
The jaw muscles are responsible for controlling jaw movements such as protrusion, retraction, elevation, depression, and rotation. These movements enable functions such as chewing, grinding, and biting.
Some common problems that can occur with the jaw muscles include jaw alignment issues, such as retrognathia (when the lower jaw is too far back) or prognathia (when the lower jaw is too far forward). Other issues include jaw asymmetry, where one side of the jaw is larger or smaller than the other, and temporomandibular joint (TMJ) disorders, which can cause pain and stiffness in the jaw joints.
