Maximus Gage
The human face is made up of about 20 facial muscles, which are essential for chewing and making facial expressions. The primary muscles that enable the lower jaw to move are the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles. These muscles are responsible for the elevation, depression, protrusion, retraction, and side-to-side movement of the jaw. The lateral pterygoid muscle, in particular, is the sole muscle that causes depression of the mandible, allowing the jaw to open and close. In addition to these primary muscles, the platysma muscle, which is located in the neck, also assists with jaw movement by helping to open the mouth and enabling the lowering of the corners of the mouth and lower lip.
| Characteristics | Values |
|---|---|
| Number of Facial Muscles | 20 |
| Muscle Responsible for Lowering the Jaw | Platysma |
| Muscles Responsible for Raising the Jaw | Temporalis, Medial Pterygoid, Lateral Pterygoid, Masseter |
| Muscle Responsible for Closing the Jaw | Temporalis |
| Muscle Responsible for Pursing the Lips | Orbicularis Oris |
| Muscle Responsible for Lowering the Corners of the Mouth and Lower Lip | Platysma |
| Muscle Responsible for Frowning | Corrugator Supercilii |
| Muscle Responsible for Smiling | Levator Anguli Oris |
| Muscle Responsible for Controlling the Lower Lip | Depressor Labii Inferioris |
| Muscle Responsible for Controlling the Centre of the Chin | Mentalis |
| Muscle Responsible for Opening the Nostrils and Lifting the Upper Lip | Levator Labii Superioris Alaeque Nasi |
| Muscle Responsible for Wrinkling the Forehead and Raising the Eyebrows | Occipitofrontalis |
| Muscle Responsible for Pulling the Eyebrows Downward | Procerus |
| Muscle Disorders | Myofascial Pain, Myositis, Neoplasms, Bruxism, TMJ Dysfunction |
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What You'll Learn
- The lateral pterygoid muscle is the primary muscle of the inferior temporal fossa
- The temporalis, medial pterygoid, lateral pterygoid, and masseter muscles are the primary muscles for mastication
- Masticatory muscle disorders include myofascial pain, myositis, and neoplasms
- Bruxism is characterised by involuntary teeth grinding and clenching
- Platysma is a muscle that helps open the mouth and control the corners of the mouth and lower lip
The lateral pterygoid muscle is the primary muscle of the inferior temporal fossa
The human face has about 20 facial muscles that are essential for chewing and making facial expressions. The muscles of mastication, or chewing, are the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles. These muscles attach to the rami of the mandible and function to move the jaw. The lateral pterygoid muscle has two parts: an upper head and a lower head. The upper head arises from the infratemporal surface and crest of the greater wing of the sphenoid bone, while the lower head arises from the lateral surface of the lateral pterygoid plate of the sphenoid bone.
The lateral pterygoid muscle fibres converge inferiorly, forming a tendon that inserts into a depression in the neck of the mandible, known as the pterygoid fovea. This muscle is supplied by a branch of the anterior division of the mandibular nerve and receives its blood supply from the pterygoid branch of the second part of the maxillary artery. The lateral pterygoid is the only muscle of mastication that causes depression of the mandible, allowing the jaw to open and close. This movement is largely the result of gravity.
The lateral pterygoid muscle also assists with protrusion and side-to-side movement of the mandible, helping to bring the teeth together during the chewing process. The mandibular movements of mastication include elevation, depression, protrusion, retraction, and side-to-side motion. These movements not only aid in chewing but also assist in grinding food by moving the mandible from side to side.
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The temporalis, medial pterygoid, lateral pterygoid, and masseter muscles are the primary muscles for mastication
The human face has about 20 facial muscles that help with chewing and making facial expressions. The temporalis, medial pterygoid, lateral pterygoid, and masseter muscles are the primary muscles involved in mastication, or the process of chewing food. These four main muscles attach to the rami of the mandible (jawbone) and function to move the jaw. The movements of the mandible during mastication include elevation, depression, protrusion, retraction, and side-to-side movement. The side-to-side motion helps grind food during the process of eating. These muscles also work to approximate or bring the teeth together and close the jaw.
The temporalis muscle is fan-shaped and assists in closing the jaw. The lateral pterygoid muscle has two parts: an upper head and a lower head. This muscle is responsible for causing depression of the mandible, which is largely due to gravity. It also assists with protrusion and side-to-side movement of the mandible. The medial pterygoid muscle, along with the lateral pterygoid, is involved in the complex movements of the mandible during mastication.
Mastication disorders can cause pain and dysfunction in these muscles. Masticatory myofascial pain is characterised by a dull, regional ache with trigger points that produce referred pain, which increases during function. Masticatory myalgia causes a dull, persistent ache over the jaw and temple muscles, and can also affect the head, neck, ear, and teeth. Myospasm, or muscle cramp, results from a sudden, involuntary, and continuous tonic contraction of the muscle.
Bruxism, or teeth grinding, is a condition that can put extremely powerful forces on the masticatory muscles, often causing tooth wear, muscle pain, and headaches. It can occur during sleep, usually during light sleep, and can cause sleep disruption for bed partners due to the grinding noise. Tumours, although rare, may also present in the mastication space.
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Masticatory muscle disorders include myofascial pain, myositis, and neoplasms
The muscles of mastication are the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles. These muscles attach to the rami of the mandible and function to move the jaw. The lateral pterygoid is the sole muscle of mastication that causes depression of the mandible. The temporalis is a fan-shaped muscle that helps the jaw close.
Myofascial pain and dysfunction may result from several etiologies, the most common being nocturnal bruxism, habitual clenching of the mouth, and whiplash injuries. Bruxism is an involuntary, repetitive oral activity characterised by teeth clenching or grinding. It can occur during sleep or while awake. Sleep bruxism can cause temporomandibular joint (TMJ) dysfunction, which results from an imbalance of forces within the muscles of mastication. TMJ dysfunction can also be caused by parafunctional behaviours that irritate and inflame the muscles of mastication, such as clenching.
Other masticatory muscle disorders include myospasm, which is characterised by acute shortening of a single muscle and may lead to pain on movement. Centrally mediated myalgia is a rare disorder caused by chronic painful stimulation of the muscle, resulting in constant pain.
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Bruxism is characterised by involuntary teeth grinding and clenching
The mandible, or jaw, is controlled by several muscles, including the platysma, which assists in depressing the mandible, and the buccinator, which helps with mastication by keeping food pushed back within the oral cavity. The four main muscles of mastication are the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles. These muscles attach to the rami of the mandible and function to move the jaw. The lateral pterygoid is the sole muscle of mastication that causes depression of the mandible, largely due to gravity. The temporalis muscle is fan-shaped and helps the jaw to close.
The buccolabial muscles are a group of muscles found in and around the mouth. These include the buccinator, a thin muscle in the cheek that holds it toward the teeth, and the depressor anguli oris, which is on the side of the chin and works with other muscles to produce a frown. The mentalis muscle, located towards the centre of the chin, helps control the lower lip.
There are several risk factors that can contribute to bruxism. These include stress, anxiety, sleep disorders, and certain medications. It is important to manage bruxism symptoms through regular dental check-ups, practising mindfulness, and avoiding smoking, alcohol, caffeine, and recreational drugs.
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Platysma is a muscle that helps open the mouth and control the corners of the mouth and lower lip
The platysma muscle is a superficial muscle in the human neck that overlaps the sternocleidomastoid. It covers the anterior surface of the neck superficially. The platysma muscle helps open the mouth and controls the corners of the mouth and the lower lip.
The platysma muscle is a broad sheet of muscle arising from the fascia covering the upper parts of the pectoralis major muscle and the deltoid muscle. Its fibres cross the clavicle and proceed obliquely upward and medially along the side of the neck. The platysma muscle is vulnerable to tears, strains, and muscle atrophy, among other possible conditions. It is also susceptible to neck injuries as it is both superficial and thin.
The anterior portion of the platysma muscle, the thickest part, depresses the lower jaw. It also draws down the lower lip and angle of the mouth in a frown. However, the platysma muscle plays only a minor role in depressing the lower lip, which is primarily performed by the depressor anguli oris muscle and the depressor labii inferioris muscle.
The platysma muscle is involved in mastication, the process of chewing food. It is one of the four main muscles of mastication, along with the temporalis, medial pterygoid, and lateral pterygoid muscles. These muscles attach to the rami of the mandible and function to move the jaw. The platysma muscle specifically assists with depressing the mandible against resistance.
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Frequently asked questions
The temporalis, medial pterygoid, lateral pterygoid, and masseter muscles are the primary muscles that move the jaw (mandible).
The cardinal mandibular movements are elevation, depression, protrusion, retraction, and side-to-side movement.
The lateral pterygoid muscle functions as the sole muscle of mastication to cause depression of the mandible.
