Victor Forge
The pterygoid muscles are a group of muscles that play a crucial role in the functioning of the temporomandibular joint (TMJ), enabling essential activities such as chewing, biting, and speaking. The group consists of the lateral pterygoid and medial pterygoid muscles, both of which have distinct roles and attachments. The lateral pterygoid muscle, with its two heads or bellies, is responsible for depressing and protruding the mandible, contributing to the complex movements of the TMJ. On the other hand, the medial pterygoid muscle, with its thick quadrilateral structure, aids in elevating the mandible and closing the mouth. These pterygoid muscles are anchored within the intricate anatomy of the skull and mandible, contributing to the smooth and coordinated movements necessary for various oral functions.
| Characteristics | Values |
|---|---|
| Number of pterygoid muscles | 2 |
| Types | Lateral pterygoid, Medial pterygoid |
| Location | Lateral pterygoid: infratemporal fossa of the skull; Medial pterygoid: arises from the medial surface of the lateral plate of the pterygoid process and the pyramidal process of the palatine bone |
| Innervation | Lateral pterygoid: nerve to the lateral pterygoid muscle, a branch of the mandibular nerve (CN V3); Medial pterygoid: medial pterygoid nerve, a branch of the mandibular nerve (V) |
| Blood Supply | Lateral pterygoid: pterygoid branches of the maxillary artery; Medial pterygoid: pterygoid branches of the maxillary artery |
| Function | Lateral pterygoid: protrusion and depression of the mandible, rotation of the mandible; Medial pterygoid: elevation of the mandible, protrusion of the mandible, mastication |
| Dysfunction | Lateral pterygoid dysfunction can cause lockjaw and contribute to temporomandibular disorders (TMD); Medial pterygoid dysfunction can impact mastication and cause issues with closing the mouth |
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What You'll Learn
The lateral pterygoid muscle
The fibres from both heads converge and insert on the pterygoid fovea on the neck of the condyloid process of the mandible. The superior fibres also insert into the anteromedial part of the articular capsule and articular disc of the temporomandibular joint (TMJ). The lateral pterygoid is one of four masticatory muscles, along with the medial pterygoid, temporalis, and masseter muscles. These muscles act on the TMJ to enable chewing and biting.
The primary function of the lateral pterygoid muscle is to protrude and depress the mandible, lowering it and opening the jaw. This is achieved by bilateral contraction of the muscle. When the muscle contracts unilaterally, it rotates the mandible, moving it side to side. The lateral pterygoid is the only muscle among the four muscles of mastication that participates in depressing the mandible. The unilateral contraction of the lateral pterygoid with the ipsilateral medial pterygoid results in lateral mandibular movement to the contralateral side. This movement is observable during functional and parafunctional lateral excursive movements, such as chewing, masticating, and clenching.
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The medial pterygoid muscle
The pterygoid muscles are two of the four muscles of mastication, located in the infratemporal fossa of the skull. These muscles are: lateral pterygoid and medial pterygoid. The primary function of the pterygoid muscles is to produce movements of the mandible at the temporomandibular joint. Both muscles are innervated by branches of the mandibular division of the trigeminal nerve (CN V3), and they receive their blood supply from branches of the maxillary artery.
The bilateral contraction of the medial pterygoid muscle elevates the mandible and closes the mouth. Due to the direction of its muscle fibres, the muscle pulls the mandible forward, producing a movement known as protrusion. The unilateral contraction of the medial pterygoid, together with the lateral pterygoid, causes the mandible to swing to the opposite side. These movements are crucial for the act of chewing.
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The role of the pterygoid muscles in mastication
The pterygoid muscles, consisting of the lateral pterygoid and medial pterygoid, are two of the four muscles of mastication. They are located in the infratemporal fossa of the skull and act on the temporomandibular joint (TMJ) to enable essential functions such as chewing, biting, and grinding.
The lateral pterygoid muscle is a short, two-headed muscle. Its primary function is to protrude and depress the mandible during bilateral contraction, and it also contributes to the rotation of the mandible during unilateral contraction. The lateral pterygoid is supplied by the lateral pterygoid nerve, a branch of the mandibular nerve (CN V3), and receives its blood supply from the pterygoid branches of the maxillary artery.
The medial pterygoid muscle is a thick, quadrilateral muscle with a superficial head and a deep head. The deep head is larger and originates from the medial surface of the lateral pterygoid plate, while the smaller superficial head originates from the maxillary tuberosity. The medial pterygoid muscle fibres converge and insert onto the medial ramus of the mandible, contributing to the elevation of the mandible and the closure of the mouth. It is innervated by the medial pterygoid branch of the mandibular nerve (CN V3) and receives its blood supply from the pterygoid branches of the maxillary artery.
Together, the lateral and medial pterygoid muscles play a crucial role in mastication by producing movements of the mandible at the temporomandibular joint. These movements include protrusion, where the mandible is pushed forward, retraction, which pulls the mandible backward, elevation, which closes the mouth, depression, which opens the mouth, and rotation, resulting in side-to-side movements of the mandible.
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The pterygoid muscles' innervation and blood supply
The pterygoid muscles, namely the lateral pterygoid and the medial pterygoid, are two of the four muscles of mastication. They are located in the infratemporal fossa of the skull and act on the temporomandibular joint to enable chewing and biting.
Innervation
The lateral pterygoid muscle is innervated by the nerve to the lateral pterygoid muscle, a branch of the mandibular nerve (CN V3). There is one nerve for each head. The nerve to the superior head and lateral half of the inferior head receives fibres from the buccal nerve, a branch of the mandibular nerve. The nerve to the medial half of the inferior head receives fibres directly from the mandibular nerve.
The medial pterygoid muscle is innervated by the medial pterygoid branch of the mandibular division of the trigeminal nerve (CN V3).
Blood Supply
The lateral pterygoid muscle receives blood supply from the pterygoid branches of the maxillary artery and the ascending palatine branch of the facial artery.
The medial pterygoid muscle receives blood supply from the pterygoid branches of the maxillary artery.
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The pterygoid muscles' development
The pterygoid muscles are two of the four muscles of mastication, enabling chewing and biting. They are located in the infratemporal fossa of the skull and are made up of the lateral pterygoid and the medial pterygoid muscles.
The lateral pterygoid is a two-headed, fan-shaped muscle, with superior and inferior heads. The superior head is formed by the most superomedial fibres of the muscle, which arise from the infratemporal crest of the greater wing of the sphenoid bone. The larger inferior head arises from the lateral surface of the lateral pterygoid plate. The fibres from both heads converge to insert into the pterygoid fovea on the neck of the mandible. The superior attachment onto the temporomandibular joint (TMJ) allows the muscle head to act on the superior compartment of the joint, producing gliding motions of the disc and mandibular condyle. The inferior head acts on the inferior compartment of the TMJ, facilitating the hinge-like rotation that occurs between the mandibular condyle and the inferior surface of the articular disc. The lateral pterygoid is supplied by the pterygoid branches of the maxillary artery and the lateral pterygoid nerve, a branch of the mandibular nerve (CN V3).
The medial pterygoid is a thick quadrilateral muscle with two heads, a superficial and a deep head. The deep head originates from the medial surface of the lateral plate of the pterygoid process and the pyramidal process of the palatine bone. The two heads of the medial pterygoid insert onto the triangular impression located on the medial surface of the mandible. The medial pterygoid is supplied by the pterygoid branches of the maxillary artery and is innervated by the medial pterygoid branch of the mandibular division of the trigeminal nerve (CN V3).
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Frequently asked questions
The pterygoid muscles are two of the four muscles of mastication: the lateral pterygoid and the medial pterygoid. They are 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). It has two heads, superior and inferior, and the inferior is three times larger than the superior. 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.
The medial pterygoid muscle is a thick quadrilateral muscle that arises by two heads, a superficial and a deep head. It has functions including elevating the mandible (closing the mouth), protruding the mandible, and excursing the mandible.
The lateral pterygoid muscle is supplied by the lateral pterygoid nerve, a branch of the mandibular nerve (CN V3). The medial pterygoid muscle is supplied by the medial pterygoid nerve, a branch of the mandibular nerve, itself a branch of the trigeminal nerve (V).
