Alec Titan
The muscles of mastication are a group of muscles that enable chewing and grinding food by moving the jaw. They are also responsible for closing the mouth and bringing the teeth together. The four main muscles of mastication are the masseter, temporalis, medial pterygoid, and lateral pterygoid muscles. These muscles originate from the surface of the skull and attach to the mandible, allowing for movements such as elevation, depression, protrusion, retraction, and side-to-side motion.
| Characteristics | Values |
|---|---|
| Definition | Group of muscles responsible for the chewing movement of the mandible at the temporomandibular (TMJ) joint |
| Number of Main Muscles | 4 |
| Names of Main Muscles | Temporalis, Masseter, Medial Pterygoid, Lateral Pterygoid |
| Location of Temporalis Muscle | Temporal Fossa |
| Location of Masseter Muscle | Cheek Area |
| Location of Medial and Lateral Pterygoids | Infratemporal Fossa |
| Innervation | Motor branches of the mandibular division of the trigeminal nerve |
| Blood Supply | Masseteric artery, a branch of the maxillary artery |
| Function of Masseter Muscle | Elevate the mandible, approximate the teeth |
| Function of Lateral Pterygoid Muscle | Depression of the mandible, protrusion, and side-to-side movement |
| Function of Temporalis Muscle | Elevate the mandible, retract the mandible |
| Function of Medial Pterygoid Muscle | Closing and lateral movements of the mandible |
| Jaw Opening Assisted By | Digastric, Geniohyoid, Mylohyoid, Omohyoid, Sternohyoid, Sternothyroid, Stylohyoid, and Thyrohyoid muscles |
| Jaw Closing Reflex | Facilitated by mesencephalic trigeminal nucleus afferents |
Explore related products
What You'll Learn
The four main mastication muscles
The temporalis muscle is a fan-shaped muscle with fibres oriented vertically, obliquely, and horizontally. It originates from the temporal fossa of the skull and inserts on the coronoid process of the mandible, elevating and retracting the mandible. The medial pterygoid muscle is thick and rectangular with a superficial and deep head. It originates from the maxillary tuberosity and the pyramidal process of the palatine bone, attaching to the ramus of the mandible.
The lateral pterygoid muscle has two parts: an upper head and a lower head. It is triangular in shape with horizontally oriented fibres. The upper head originates from the inferior temporal surface of the greater wing of the sphenoid bone, while the lower head originates from the lateral aspect of the lateral pterygoid plate of the sphenoid bone. The fibres converge to form a tendon that inserts on the neck of the mandible. The lateral pterygoid muscle is the sole muscle responsible for depressing the mandible, and it also assists with protrusion and side-to-side movement.
The masseter muscle is rectangular with three layers: superficial, intermediate, and deep. It originates from the inferior zygomatic arch and the anterior two-thirds of the zygomatic arch, attaching to the outer surface of the mandibular ramus and the coronoid process of the mandible. The masseter muscle elevates the mandible and approximates the teeth.
Chest Muscles: Intimidating or Attractive?
You may want to see also
Explore related products
Jaw movement
The muscles of mastication are a group of muscles responsible for the chewing movement of the mandible (jawbone) at the temporomandibular joint (TMJ). These muscles enhance the process of eating by assisting in grinding food and bringing the teeth together.
The four main muscles of mastication are the masseter, temporalis, medial pterygoid, and lateral pterygoid. They attach to the rami of the mandible and function to move the jaw. The mandibular nerve (CN V3) is the largest and most inferior division of the trigeminal nerve (CN V). It is the only division of the trigeminal nerve that carries motor fibres, which are necessary for muscle contractions.
The masseter muscle is a powerful muscle that can exert very high forces, such as during chewing, but it can also exert very low forces with incredible precision, such as during speech. The masseter receives nerve input from the masseteric nerve, a division of the mandibular nerve. Its major function is to elevate the mandible and approximate the teeth.
The temporalis muscle is fan-shaped and originates from the temporal fossa of the skull, attaching to the coronoid process of the mandible. The anterior and mid fibres of the temporalis muscle function to elevate the mandible, while the posterior fibres retract the mandible. The temporalis receives innervation from the deep temporal branches of the mandibular nerve.
The medial pterygoid muscle is thick and rectangular, with a superficial head and a deep head. It is responsible for closing and lateral movements of the mandible. The medial pterygoid nerve, a division of the mandibular nerve, supplies nerve input to this muscle.
The lateral pterygoid muscle is the primary muscle of the inferior temporal fossa and has two parts: an upper head and a lower head. This muscle is the sole muscle of mastication 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 lateral pterygoid nerves, divisions of the mandibular nerve, provide nerve supply to this muscle.
Understanding Muscle Contort: What Does it Mean?
You may want to see also
Explore related products
Mastication muscle pain
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 and assist in grinding food. The four main muscles of mastication are the masseter, temporalis, medial pterygoid, and lateral pterygoid. These muscles attach to the rami of the mandible and function to move the jaw (mandible). The cardinal mandibular movements of mastication are elevation, depression, protrusion, retraction, and side-to-side movement.
Masticatory myospasm, also known as a muscle cramp, is an acute condition resulting from a sudden, involuntary, and continuous tonic contraction of the muscle. This condition can lead to trismus (lockjaw), severely limited range of motion of the mandible, and pain on movement. Myofibrotic contracture involves a painless shortening of the muscle due to fibrosis, which can also result in limited mouth opening. Myositis is an inflammatory condition of the muscles caused by trauma or infection, leading to swelling, redness, increased temperature, jaw dysfunction, and limited range of motion.
Bruxism is another condition that can cause mastication muscle pain. It involves involuntary, aimless, and repetitive teeth clenching or grinding, which can occur during sleep or while awake due to various psychological, neurological, and orodental conditions. Bruxism can cause tooth wear and destruction, temporomandibular joint and muscle pain, and tension-type headaches.
Physiotherapy treatments for mastication muscle pain may include manual therapy techniques such as trigger point release, massage, and stretching, as well as exercises to improve the range of motion of the jaw. Therapeutic exercises aim to increase the flexibility of the muscles involved in jaw movement, while manual therapy techniques like ischaemic compression help to alleviate pain by applying pressure to specific points in the muscle to decrease muscle tension. Dry needling is another unconventional intervention that involves inserting a thin needle into the trigger point of the muscle to relieve pain and improve function.
Developing a Strong QL Core Muscle for Athletes
You may want to see also
Explore related products
Accessory mastication muscles
Mastication, or chewing, is enabled by a group of muscles that produce movements of the lower jaw at the temporomandibular joint (TMJ). 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 facilitate the cardinal mandibular movements of mastication: elevation, depression, protrusion, retraction, and side-to-side movement.
The muscles of mastication can be further divided into primary and secondary, or accessory, muscles. The accessory muscles of mastication include the buccinator, suprahyoid muscles, and infrahyoid muscles. The suprahyoid muscle group is made up of the digastric muscle, mylohyoid muscle, and geniohyoid muscle. The infrahyoid muscle group includes the sternohyoid, sternothyroid, thyrohyoid, and omohyoid muscles.
The buccinator is a facial expression muscle that assists in mastication by keeping food pushed back within the oral cavity. The infrahyoid muscles fix or depress the hyoid bone, while the suprahyoid muscles depress the mandible against resistance when the infrahyoid muscles depress the hyoid bone.
Injecting the DAO Muscle: A Comprehensive Guide
You may want to see also
Explore related products
Innervation and vascularisation
Mastication, or chewing, is a crucial process in the digestion of food, and it is facilitated by a group of muscles known as the mastication muscles. These muscles are innervated by the trigeminal nerve, also known as the fifth cranial nerve, which plays a key role in sensory processing and motor function in the head and face.
The trigeminal nerve has three main branches: the ophthalmic branch, the maxillary branch, and the mandibular branch. It is the mandibular branch, or the inferior dental nerve, that is specifically responsible for innervating the muscles of mastication. This branch emerges from the trigeminal ganglion and runs a course through the skull to supply these muscles.
The mandibular nerve provides motor innervation to the muscles of mastication, which includes the temporalis, masseter, medial pterygoid, and lateral pterygoid muscles. Each of these muscles plays a specific role in the complex movements of the jaw during chewing, speaking, and other oral functions.
In terms of vascular supply, the mastication muscles receive their blood supply from several arteries, including the maxillary artery, the superficial temporal artery, and the posterior auricular artery. These arteries branch out and form a network of smaller vessels that penetrate the muscles, ensuring a sufficient oxygen and nutrient supply for their function and metabolism.
The venous drainage of the mastication muscles is through a network of veins that accompany the arteries and drain into larger venous structures, such as the pterygoid plexus and the facial and retromandibular veins. This venous drainage ultimately connects to the dural venous sinuses and drains into the internal jugular vein.
The understanding of innervation and vascularisation of the mastication muscles is important not only for comprehending the physiology of chewing but also for clinical applications. Any damage or pathology affecting the trigeminal nerve or the vascular supply can lead to significant impairments in mastication and oral function, highlighting the critical role of these structures in our daily lives.
Mewing for Muscle Growth: Does It Work?
You may want to see also
Frequently asked questions
Mastication muscles are a group of muscles that enable chewing and grinding food by moving the jaw.
The primary mastication muscles are the masseter, temporalis, medial pterygoid, and lateral pterygoid muscles.
The temporalis muscle is a fan-shaped muscle that lies within the temporal fossa of the skull. Its functions include elevating and retracting the mandible.
