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The pterygoid muscles are two of the four muscles of mastication, located in the infratemporal fossa of the skull. These include the medial pterygoid muscle and the lateral pterygoid muscle. The primary function of the pterygoid muscles is to produce movements of the mandible at the temporomandibular joint, which is crucial for the act of chewing. Dysfunction of the lateral pterygoid muscle may contribute to temporomandibular disorders.
| Characteristics | Values |
|---|---|
| Function | Producing movements of the mandible at the temporomandibular joint, protruding and depressing the mandible, lowering the mandible and opening the jaw, elevating the mandible, closing the mouth, mastication, and rotating the mandible |
| Composition | Two muscles: the medial pterygoid and the lateral pterygoid |
| Location | The infratemporal fossa of the skull |
| Innervation | Branches of the mandibular division of the trigeminal nerve (CN V3) |
| Blood Supply | Branches of the maxillary artery |
| Structure | The medial pterygoid has two heads, a deep head and a superficial head. The lateral pterygoid also has two heads, an upper head and a lower head, with the inferior head being much wider than the superior head. |
| Origin | The medial pterygoid originates from the lamina lateralis of the pterygoid process. The lateral pterygoid originates from the lateral surface of the lateral pterygoid plate of the sphenoid bone. |
| Insertion | The medial pterygoid inserts into the lower and back part of the medial surface of the ramus and angle of the mandible. The lateral pterygoid inserts into the pterygoid fovea on the neck of the condyloid process of the mandible. |
| Dysfunction | Possible contribution to temporomandibular disorders and painful spasms |
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What You'll Learn
- Pterygoid muscles are two of the four muscles of mastication
- They control movement of the temporomandibular joint (TMJ)
- The medial pterygoid muscle has a thick, quadrilateral shape
- The lateral pterygoid muscle has upper and lower heads
- Dysfunction of the lateral pterygoid may cause temporomandibular disorders
Pterygoid muscles are two of the four muscles of mastication
The pterygoid muscles are two of the four muscles of mastication, located in the infratemporal fossa of the skull. These muscles are the lateral pterygoid and medial pterygoid. The primary function of the pterygoid muscles is to produce movements of the mandible at the temporomandibular joint. The temporomandibular joint, or TMJ, is responsible for enabling functions such as chewing and grinding. The muscles of mastication are a group of muscles that consist of the temporalis, masseter, medial pterygoid, and lateral pterygoid muscles. Three of these muscles are responsible for the adduction of the mandible, while one helps in the abduction of the mandible.
The lateral pterygoid muscle is a short, two-headed muscle, located in the infratemporal fossa of the skull. Its upper head arises from the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone, while the larger lower head arises from the lateral surface of the lateral pterygoid plate of the sphenoid bone. The fibres of both heads merge and insert on the pterygoid fovea on the neck of the mandible. The lateral pterygoid muscle is innervated by the nerve to the lateral pterygoid muscle, which is a branch of the mandibular division of the trigeminal nerve. It receives blood supply from the pterygoid branches of the maxillary artery and the ascending palatine branch of the facial artery. The function of the lateral pterygoid muscle is to protrude and depress the mandible when contraction is bilateral. In unilateral contraction, the lateral pterygoid muscle moves the mandible medially, assisting in side-to-side movement.
The medial pterygoid muscle is a thick quadrilateral muscle that arises from two heads, a superficial and a deep head. The smaller superficial head originates from the maxillary tuberosity and pyramidal process of the palatine bone. The larger deep head originates from the medial surface of the lateral plate of the pterygoid process and the pyramidal process of the palatine bone. The medial pterygoid muscle fibres converge inferiorly, forming a tendon that inserts on the medial ramus of the mandible. The medial pterygoid muscle is innervated by the medial pterygoid branch of the mandibular nerve.
The muscles of mastication can be divided into primary muscles and secondary or accessory muscles. The masseter muscle, for example, is a primary muscle of mastication that covers most of the lateral aspect of the ramus. It consists of three layers that blend anteriorly: the superficial layer, intermediate layer, and deep layer. The fibres of the muscle originate from the inferior zygomatic arch and the anterior two-thirds of the zygomatic arch, with a connection to the posterior aspect of the zygomatic bone.
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They control movement of the temporomandibular joint (TMJ)
The pterygoid muscles are two of the four muscles of mastication, located in the infratemporal fossa of the skull. The lateral pterygoid muscle is a craniomandibular muscle that helps control movement of the temporomandibular joint (TMJ). The superior head of the lateral pterygoid muscle is formed by the most superomedial fibres of the muscle, which originate from the infratemporal crest of the greater wing of the sphenoid bone. The inferior head, which is much wider than the superior one, originates from the lateral surface of the lateral pterygoid plate of the sphenoid bone. The lateral pterygoid muscle comprises the medial wall of the infratemporal fossa and is contained within the masticator space.
The primary function of the lateral pterygoid muscle is to pull the head of the condyle out of the mandibular fossa along the articular eminence to protrude the mandible. It depresses and protrudes the mandible, and when each muscle works independently, they can move the mandible side to side. The lateral pterygoid muscle also contributes to the function of the TMJ by protruding and depressing the mandible when contracting bilaterally, and by rotating the mandible when contracting unilaterally. The superior attachment onto the TMJ enables the muscle head to act on the superior compartment of the joint, producing the gliding motions of the disc and mandibular condyle.
The medial pterygoid muscle, on the other hand, has functions including elevating the mandible (closing the mouth), protruding the mandible, mastication (especially when the maxillary and mandibular teeth are close together), and excursing the mandible (contralateral excursion occurs with unilateral contraction). The medial pterygoid nerve is a main trunk from the mandibular nerve, before the division of the trigeminal nerve. Dysfunction of the lateral pterygoid muscle may contribute to temporomandibular disorders, and painful spasms of the muscle may serve as a protective mechanism to unload the TMJ by pulling the mandible forward. However, chronic spasms can cause the disc to become misaligned, leading to abnormal clicking of the jaw during opening and closing.
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The medial pterygoid muscle has a thick, quadrilateral shape
The pterygoid muscles are two of the four muscles of mastication, located in the infratemporal fossa of the skull. The medial pterygoid muscle is a thick, quadrilateral-shaped muscle that connects the mandible with the maxilla, sphenoid, and palatine bones. It is comprised of two heads: a superficial head and a deep head. The smaller superficial head originates from the maxillary tuberosity and pyramidal process of the palatine bone. The larger deep head originates from the medial surface of the lateral plate of the pterygoid process and the pyramidal process of the palatine bone. The deep part forms the bulk of the muscle. The two heads of the medial pterygoid muscle insert onto the triangular impression located on the medial surface of the mandible.
The medial pterygoid muscle is innervated by the medial pterygoid branch of the mandibular division of the trigeminal nerve (CN V3). It receives blood supply from the pterygoid and buccal branches of the maxillary artery. The outer surface of the medial pterygoid muscle is related to the process of the parotid gland, while the inner surface is connected to the tensor veli palatini, styloglossus, and salpingopharyngeus muscles. The medial pterygoid muscle is involved in several actions due to its posteroinferior direction and mobile mandibular attachment. Unilateral contraction of the medial pterygoid muscle causes a slight medial rotation of the mandible. When this occurs simultaneously with the contraction of the ipsilateral lateral pterygoid, the same-sided part of the mandible swings anteriorly and medially. Alternating contractions of the medial and lateral pterygoid muscles result in side-to-side movements of the mandible. Bilateral contraction of the medial pterygoid muscle elevates the mandible, and when combined with bilateral contraction of the lateral pterygoid, it protrudes the mandible.
The primary function of the pterygoid muscles is to produce movements of the mandible at the temporomandibular joint, enabling chewing and biting. The medial pterygoid muscle, along with the lateral pterygoid, contributes to the act of chewing by facilitating the swinging of the mandible to the opposite side. The lateral pterygoid muscle, on the other hand, has an upper and lower head and contributes to the function of protruding and depressing the mandible when contracting bilaterally and rotating the mandible when contracting unilaterally.
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The lateral pterygoid muscle has upper and lower heads
The lateral pterygoid muscle is a two-headed, fan-shaped muscle located in the infratemporal fossa of the skull. It is one of the four masticatory muscles, along with the medial pterygoid, temporalis, and masseter muscles. These muscles act on the temporomandibular joint (TMJ) to enable chewing (mastication) and biting. The lateral pterygoid muscle has an upper head and a lower head.
The upper head of the lateral pterygoid muscle, also known as the superior head, is smaller in size. It originates from the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone. The superior head consists of muscular slips that originate from the infratemporal crest of the sphenoid bone. The fibres from the superior head insert into the anteromedial part of the articular capsule and the articular disc of the temporomandibular joint. This attachment allows the muscle head to act on the superior compartment of the joint, producing gliding motions of the disc and mandibular condyle.
The lower head of the lateral pterygoid muscle, also referred to as the inferior head, is larger than the superior head. It originates from the lateral surface of the lateral pterygoid plate of the sphenoid bone. The fibres from the inferior head insert into the pterygoid fovea on the neck of the condyloid process of the mandible. The inferior head acts on the inferior compartment of the TMJ, facilitating a hinge-like rotation between the mandibular condyle and the inferior surface of the articular disc.
The fibres from both the upper and lower heads converge and course posterolaterally in a predominantly horizontal plane. The maxillary artery and buccal nerve pass through the split between the superior and inferior heads of the lateral pterygoid muscle. The primary function of the lateral pterygoid muscle is to protrude and depress the mandible during bilateral contraction, contributing to the opening of the jaw. When acting unilaterally, the lateral pterygoid muscle moves the mandible medially, enabling side-to-side movements when working independently.
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Dysfunction of the lateral pterygoid may cause temporomandibular disorders
The pterygoid muscles are two of the four muscles of mastication, located in the infratemporal fossa of the skull. The lateral pterygoid muscle is supplied by pterygoid branches of the maxillary artery. It has two "heads" that originate from sections of the skull's sphenoid bone. Both of the heads of the lateral pterygoid attach to the mandibular condyle, where the lower jawbone and the temporomandibular joint meet. The primary function of the lateral pterygoid muscle is to pull the head of the condyle out of the mandibular fossa along the articular eminence to protrude the mandible. It also contributes to lowering the mandible and opening the jaw.
The lateral pterygoid muscle is responsible for moving the jaw. When each muscle works independently, they can move the mandible side to side. The lateral pterygoid muscle also contributes to the act of chewing by protruding and depressing the mandible when contracting bilaterally and by rotating the mandible when contracting unilaterally.
Temporomandibular disorders (TMD) are a group of common but complex conditions that affect the jaw and surrounding areas, often due to a variety of underlying anatomical factors. Dysfunction of the TMJ can cause severe pain and lifestyle limitations. The lateral pterygoid muscle is one of the muscles that can play a role in any number of TMJ disorders. Trigger points in the lateral pterygoid can cause sinus pain, throat discomfort, and even tinnitus. These points may refer pain to the temporomandibular joint (TMJ) and maxillary sinus region, and can be linked to increased mucus secretion and limited jaw movement.
TMJ arthralgia is a condition within TMD that refers to pain and inflammation inside the joints. The National Institute of Dental and Craniofacial Research estimates that more than 10 million Americans experience some type of TMJ disorder, with more women experiencing it than men.
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Frequently asked questions
The medial pterygoid muscle is involved in the following functions:
- Elevating the mandible (closing the mouth)
- Protruding the mandible
- Mastication (especially when the maxillary and mandibular teeth are close together)
- Excursing the mandible (contralateral excursion occurs with unilateral contraction)
The lateral pterygoid muscle is a craniomandibular muscle that helps control movement of the temporomandibular joint (TMJ). It has the following functions:
- Pulling the head of the condyle out of the mandibular fossa along the articular eminence to protrude the mandible
- Lowering the mandible and opening the jaw
- Protruding and depressing the mandible when contracting bilaterally
- Rotating the mandible when contracting unilaterally
The pterygoid muscles are two of the four muscles of mastication, located in the infratemporal fossa of the skull. They produce movements of the mandible at the temporomandibular joint.
