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The pterygoid muscles, comprising the lateral and medial pterygoid muscles, are two of the four muscles of mastication, located in the infratemporal fossa of the skull. The lateral pterygoid muscle is innervated by the nerve to the lateral pterygoid muscle, a branch of the mandibular division of the trigeminal nerve (CN V3). On the other hand, the medial pterygoid muscle is innervated by the medial pterygoid branch of the mandibular division of the trigeminal nerve (CN V3).
| Characteristics | Values |
|---|---|
| Innervation of the lateral pterygoid muscle | The nerve to the lateral pterygoid muscle, a branch of the mandibular division of the trigeminal nerve (CN V3) |
| Innervation of the medial pterygoid muscle | The medial pterygoid nerve, a branch of the mandibular nerve (CN V3), which is a division of the trigeminal nerve (CN V) |
| Blood supply to the lateral pterygoid muscle | The pterygoid branch of the maxillary artery, and the ascending palatine branch of the facial artery |
| Blood supply to the medial pterygoid muscle | The pterygoid and buccal branches of the maxillary artery, and to a lesser extent, the ascending palatine artery and muscular branches of the facial artery |
| Function of the lateral pterygoid muscle | Protrusion, depression, and abduction of the mandible |
| Function of the medial pterygoid muscle | Elevation, protrusion, and rotation of the mandible |
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What You'll Learn
The lateral pterygoid nerve
The lateral pterygoid muscle is a craniomandibular muscle with two heads or bellies. It is located in the infratemporal fossa of the skull and plays a crucial role in the inferior temporal region. The primary function of this muscle is to produce movements of the mandible at the temporomandibular joint, such as protrusion (forward movement of the mandible), abduction (depression of the mandible), and mediotrusion (movement of the mandibular condyle towards the midline).
The superior belly of the lateral pterygoid muscle was classically described to function in closing the mouth, while the inferior belly was believed to be involved in depressing, protruding, and deviating the mandible to the contralateral side. However, recent studies suggest that the two bellies may have similar functions due to misinterpretations of electromyography (EMG) studies. The superior belly may also be active during mouth opening, protrusion, and contralateral deviation, similar to the functions of the inferior belly.
The lateral pterygoid muscle receives its blood supply from the pterygoid branches of the maxillary artery and the ascending palatine branch of the facial artery. It is important to note that the lateral pterygoid nerve provides innervation to both heads of the lateral pterygoid muscle, with one nerve supplying each head.
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The medial pterygoid nerve
The medial pterygoid muscle is located in the infratemporal fossa, lying deep to the masseter and temporalis muscles and medial to the lateral pterygoid muscle. The outer surface of the muscle lies against the inner surface of the mandible, from which it is separated by the lateral pterygoid muscle, the sphenomandibular ligament, the maxillary artery, the mandibular nerve, and its lingual and inferior alveolar branches. The medial pterygoid muscle can sometimes be injured during an inferior alveolar nerve block if the anesthetic needle is placed too medially, resulting in a hemorrhage and the development of medial pterygoid trismus.
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The mandibular nerve
The medial pterygoid muscle is a thick, quadrangular-shaped muscle, also referred to as a square-shaped muscle, with 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 pterygoid plate of the sphenoid bone. The medial pterygoid muscle is responsible for elevating the mandible (closing the mouth), protruding the mandible, and rotating the mandible. The unilateral contraction of the medial pterygoid muscle causes the mandible to rotate, while bilateral contraction elevates and protrudes it. This muscle is innervated by the medial pterygoid nerve, a branch of the mandibular nerve.
The lateral pterygoid muscle is a craniomandibular muscle with two heads or bellies: the superior belly and the inferior belly, which is three times larger. The superior head originates from the greater wing of the sphenoid bone, while the inferior head originates from the lateral surface of the lateral pterygoid plate. The lateral pterygoid muscle is responsible for depressing and protruding the mandible, as well as moving the mandible medially. The lateral pterygoid muscle is innervated by the nerve to the lateral pterygoid muscle, a branch of the mandibular nerve.
The pterygoid muscles receive their blood supply from the pterygoid branches of the maxillary artery. The medial pterygoid muscle also receives some blood supply from the facial artery, while the lateral pterygoid muscle receives blood supply from the ascending palatine branch of the facial artery.
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The trigeminal nerve
The pterygoid muscles, namely the lateral pterygoid and the medial pterygoid, are two of the four muscles of mastication, located in the infratemporal fossa of the skull. The primary function of the pterygoid muscles is to produce movements of the mandible at the temporomandibular joint.
The medial pterygoid nerve innervates the medial pterygoid muscle. This muscle is thick and quadrilateral in shape, with 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, while the larger deep head originates from the medial surface of the lateral pterygoid plate of the sphenoid bone. The medial pterygoid muscle is responsible for elevating the mandible (closing the mouth), protruding the mandible, and rotating it. It also aids in mastication, especially when the maxillary and mandibular teeth are close together.
The nerve to the lateral pterygoid muscle innervates the lateral pterygoid muscle. This muscle has a triangular shape with two heads: a superior head and an inferior head. The superior head arises from the greater wing of the sphenoid bone, while the larger inferior head originates from the lateral surface of the lateral pterygoid plate. The lateral pterygoid muscle is responsible for protruding and depressing the mandible during bilateral contraction. During unilateral contraction, it moves the mandible medially. It is active during speaking, singing, and clenching, and plays a crucial role in mandibular movements.
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The maxillary artery
The pterygoid muscles are two of the four muscles of mastication, comprising the lateral pterygoid and medial pterygoid muscles. These muscles are innervated by the mandibular division of the trigeminal nerve (CN V3). The pterygoid muscles also receive their blood supply from the pterygoid branches of the maxillary artery.
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Frequently asked questions
The lateral pterygoid muscle is innervated by the nerve to the lateral pterygoid muscle, a branch of the mandibular division of the trigeminal nerve (CN V3).
The medial pterygoid muscle is innervated by the medial pterygoid branch of the mandibular division of the trigeminal nerve (CN V3).
The primary function of the pterygoid muscles is to produce movements of the mandible at the temporomandibular joint.
