Victor Forge
Mastication muscles, also known as the muscles of mastication, are a group of muscles that enable chewing and grinding food through mandibular movement. They are innervated by the mandibular branch of the trigeminal nerve, which is the largest of the cranial nerves. The four main mastication muscles are the temporalis, masseter, medial pterygoid, and lateral pterygoid muscles. These muscles attach to the mandible, or lower jaw, and work together with accessory muscles to produce movements such as elevation, depression, protrusion, retraction, and side-to-side motion.
| Characteristics | Values |
|---|---|
| Definition | Muscles of mastication are a group of muscles responsible for the chewing movement of the mandible at the temporomandibular (TMJ) joint. |
| Number of muscles | There are four main muscles of mastication. |
| Names of muscles | Temporalis, masseter, medial pterygoid, and lateral pterygoid. |
| Muscle shape | Temporalis is fan-shaped. Masseter is quadrangular. Medial pterygoid is quadrangular with two heads. Lateral pterygoid is triangular with two heads. |
| Muscle origin | The four main muscles of mastication originate from the surface of the skull. |
| Muscle attachment | The muscles attach onto the rami of the mandible at the TMJ. |
| Function | The muscles enable functions such as chewing, grinding, and biting. They also assist in approximating the teeth (bringing them together or closing them). |
| Cardinal mandibular movements | Elevation, depression, protrusion, retraction, and side-to-side movement. |
| Innervation | Innervated by the anterior trunk of the mandibular nerve (CN V3), a branch of the trigeminal nerve (CN V). |
| Arterial supply | Arterial supply is via the maxillary artery, a branch of the external carotid artery. |
| Blood supply | Blood supply is derived from branches of the maxillary artery. |
| Related disorders | Masticatory myalgia, masticatory myospasm, temporomandibular disorders. |
Explore related products
What You'll Learn
The four main mastication muscles
Mastication, or chewing, is the first step in the digestion of food and an important process for maintaining oral health. This action is made possible by a group of muscles known as the mastication, or chewing, muscles. These muscles work together to produce the complex movements of the jaw, allowing for the grinding and breakdown of food. The four main muscles involved in mastication are the masseter, temporalis, medial pterygoid, and lateral pterygoid.
The masseter muscle is a powerful muscle located at the angle of the jaw and is responsible for the upward movement of the jaw during chewing. It is one of the strongest muscles in the body, enabling it to exert a large amount of force for activities such as chewing tough foods. The temporalis muscle sits on the side of the head, just in front of the ear, and aids in the closing of the jaw by pulling the mandible upward and backward. This muscle is crucial for biting and maintaining the stability of the mandible during chewing.
The medial pterygoid and lateral pterygoid muscles work together to control the side-to-side movement of the jaw. The medial pterygoid is located on the inner side of the jaw and assists in closing the jaw and moving it from side to side. It also plays a role in protruding the jaw forward. The lateral pterygoid is found on the outer side of the jaw and is responsible for moving the jaw backward, as well as gliding it from side to side. These muscles work in tandem to allow for the grinding motion necessary for food breakdown.
These four muscles, along with the coordination of the tongue and other oral structures, ensure that food is properly chewed and prepared for the next stages of digestion. Proper mastication is essential not only for nutrition but also for oral health, as it stimulates saliva production, which helps to clean the teeth and mouth and neutralize acids produced by bacteria. Understanding the function and importance of these mastication muscles provides insight into the complex mechanics of the human body and the processes that enable us to derive nourishment from our food.
Exhausting Your Muscles: The Ultimate Guide to Muscle Fatigue
You may want to see also
Explore related products
Their role in chewing food
The muscles of mastication are a group of muscles that enable chewing and grinding food. They are responsible for the chewing movement of the mandible at the temporomandibular (TMJ) joint. The four main muscles of mastication are the temporalis, masseter, medial pterygoid, and lateral pterygoid muscles. These muscles attach to the rami of the mandible and function to move the jaw (mandible).
The mandibular movements of mastication are elevation, depression, protrusion, retraction, and side-to-side movement. The muscles of mastication assist in grinding food by moving the mandible in a side-to-side motion. They also function to approximate or bring together the teeth. The masseter muscle, in particular, is the most powerful muscle of mastication. It is quadrangular in shape and has two parts: deep and superficial. The superficial layer arises from the maxillary process of the zygomatic bone, while the deep layer arises from the medial surface and inferior margin of the zygomatic arch.
The temporalis muscle is a large, flat muscle that lies within the temporal fossa of the skull. It is fan-shaped, with anterior fibres that have a vertical orientation, mid fibres that are oblique, and posterior fibres that are horizontal. The medial pterygoid muscle has a quadrangular shape with two heads: deep and superficial. It is located inferiorly to the lateral pterygoid. The lateral pterygoid muscle functions as the sole muscle of mastication to cause depression of the mandible. This muscle also assists with protrusion and side-to-side movement of the mandible.
In addition to the primary muscles of mastication, there are also accessory muscles that are directly or indirectly associated with mandibular function. These include the digastric, geniohyoid, mylohyoid, omohyoid, sternohyoid, sternothyroid, stylohyoid, and thyrohyoid muscles. The accessory muscles coordinate the full integration of mandibular movement during opening and closing through their attachments to the hyoid bone, the mandible, and other bones. The buccinator muscle is another accessory muscle that helps in mastication by keeping food pushed back within the oral cavity.
Building Muscle Tone: Secrets to Success
You may want to see also
Explore related products
The origin and insertion points
The muscles of mastication are a group of muscles responsible for the movement of the mandible at the temporomandibular joint (TMJ) to enable functions such as chewing and grinding food. The four main muscles of mastication are the temporalis, masseter, medial pterygoid, and lateral pterygoid muscles. These muscles originate from the surface of the skull and attach onto the rami of the mandible at the TMJ.
The temporalis muscle is a large, flat muscle that lies within the temporal fossa of the skull. This fan-shaped muscle originates from the entirety of the temporal fossa below the temporal line, as well as the deep surface of the temporal fascia. Its muscle fibres converge anteriorly to form a tendon that inserts on the apex and medial surface of the coronoid process and the anterior border of the ramus of the mandible. The origin of the temporalis muscle spans from the temporal fossa to the inferior temporal line of the lateral skull.
The masseter muscle is a strong, quadrangular muscle that covers the lateral aspect of the ramus of the mandible. It consists of two layers: the superficial layer and the deep layer. The superficial layer arises from the maxillary process of the zygomatic bone and the anterior two-thirds of the zygomatic arch. From this origin, these muscle fibres attach to the lateral surface of the angle and the lower half of the ramus of the mandible. The deep layer of the masseter muscle arises from the medial surface and inferior margin of the zygomatic arch, inserting onto the upper part of the ramus of the mandible and the coronoid process.
The medial pterygoid muscle has a quadrangular shape with two heads: the superficial head and the deep head. The superficial head originates from the maxillary tuberosity and the pyramidal process of the palatine bone, while the deep head originates from the medial aspect of the lateral pterygoid plate of the sphenoid bone. Both heads attach to the ramus of the mandible near the angle of the mandible.
The lateral pterygoid muscle has a triangular shape with two heads: the superior head and the inferior head. The superior head originates from the greater wing of the sphenoid, while the inferior head originates from the lateral pterygoid plate of the sphenoid.
Healing Muscles: Natural Ways to Speed Up Recovery
You may want to see also
Explore related products
Innervation and arterial supply
The muscles of mastication are innervated by the motor branches of the mandibular division of the trigeminal nerve (CNV3). The mandibular nerve is the largest and most inferior division of the trigeminal nerve, and it carries motor fibres. The four main muscles of mastication are innervated by the anterior trunk of the mandibular nerve.
The temporalis muscle receives innervation from the deep temporal branches of the mandibular nerve. The medial pterygoid muscle is supplied by a branch from the trunk of the mandibular nerve, while the other muscles are supplied by branches from the anterior division of the mandibular nerve. The lateral pterygoid muscle is innervated by the lateral pterygoid branch of the mandibular nerve.
The main arterial supply to the muscles of mastication comes from the maxillary artery, a branch of the external carotid artery. The masseter muscle receives its blood supply from the masseteric artery, which is a branch of the maxillary artery. The medial pterygoid muscle is supplied by the pterygoid branch of the second part of the maxillary artery. The lateral pterygoid muscle is vascularised by the pterygoid branches of the maxillary artery. The temporalis muscle is vascularised by the deep temporal branches of the maxillary artery and the middle temporal branches of the superficial temporal artery.
The Penis: Muscle or More?
You may want to see also
Explore related products
Related medical conditions
The muscles of mastication are a group of muscles responsible for the chewing movement of the mandible at the temporomandibular (TMJ) joint. They enhance the process of eating by assisting in grinding food and also function to approximate the teeth. 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 (mandible). The mandibular movements of mastication include elevation, depression, protrusion, retraction, and side-to-side movement.
The muscles of mastication are associated with several medical conditions, some of which are described below:
Masticatory Myalgia
Masticatory myalgia is characterised by a persistent dull ache in the jaw and temple muscles, sometimes extending to the head, neck, ear, and teeth. Other symptoms include restricted opening, fatigue, stiffness, and tenderness of the muscles with a limited range of motion. It is often challenging for clinicians to determine whether the primary condition is intra-articular or masticatory muscle spasm, as both can result in secondary joint inflammation and contribute to orofacial pain. Treatment with muscle relaxants and trigger point injections can help address the myalgia component of the pain.
Masticatory Myospasm
Masticatory myospasm, also known as muscle cramp, is an acute condition characterised by sudden, involuntary, and continuous tonic contraction of the muscle. It results in acute shortening of a single muscle, leading to possible trismus (lockjaw), pain on movement, and a severely limited range of motion of the mandible. The sudden onset of these symptoms helps clinicians differentiate myospasm from other masticatory muscle disorders.
Bruxism
Bruxism is an involuntary, repetitive oral activity characterised by teeth clenching or grinding. It can occur during wakefulness or sleep and is associated with various psychological, neurological, and orodental conditions. Bruxism exerts powerful forces on the teeth, periodontal structures, temporomandibular joint, and masticatory muscles, leading to tooth wear, joint pain, and tension-type headaches. Sleep bruxism can disrupt the sleep of bed partners and cause social embarrassment.
Temporomandibular Joint (TMJ) Dysfunction
TMJ dysfunction arises from an imbalance of forces within the muscles of mastication, resulting in joint pain and potential secondary inflammation.
Myofibrotic Contracture
Myofibrotic contracture involves painless shortening of the muscle due to fibrosis in and around the remaining contractile muscle tissue following an infectious process or trauma. It is characterised by limited mouth opening and resistance to passive jaw muscle stretch.
Myositis
Myositis is an inflammatory condition of the muscles caused by acute trauma or infection. It presents with swelling, redness, and increased temperature over the affected area. In dogs, a condition called Masticatory Muscle Myositis (MMM) specifically affects the muscles of mastication, causing swelling and restricted jaw movement.
Taping Technique for Gastrocnemius Muscle: A Comprehensive Guide
You may want to see also
Frequently asked questions
The muscles of mastication are a group of muscles responsible for the movement of the jaw (or mandible) at the temporomandibular joint (TMJ), enabling functions such as chewing and grinding food.
The primary muscles of mastication are the temporalis, masseter, medial pterygoid, and lateral pterygoid muscles.
The accessory muscles of mastication include the buccinator, suprahyoid, and infrahyoid muscles. The suprahyoid muscle group is made up of the digastric, mylohyoid, and geniohyoid muscles. The infrahyoid muscles include the sternohyoid, sternothyroid, thyrohyoid, and omohyoid muscles.
The mastication muscles work in a coordinated fashion to produce mandibular movement for chewing food. They enable the elevation, depression, protrusion, retraction, and side-to-side movement of the mandible.
