Anatomy and supply
The pterygoid muscles (“wing muscles”) are two jaw muscles located on the inner surface of the mandible.
- Medial pterygoid muscle: originates from the pterygoid fossa and pterygoid process of the sphenoid. Distally it inserts on the pterygoid tuberosity on the inner surface of the mandibular angle. Along with the masseter, this muscle forms a sling around the mandible. The medial pterygoid can be palpated medially to the ramus of the mandible both intra- and extraorally.
- Lateral pterygoid muscle: has two heads which lie almost horizontally to each other. The small superior head runs from the infratemporal crest of the sphenoid to the articular disc of the temporomandibular joint. The much larger inferior head courses from the pterygoid process of sphenoid to the condylar process of mandible. Due to its anatomy, palpation of the lateral pterygoid is quite difficult.
Both muscles are innervated by nerves which have the same name and branch out from the mandibular nerve (medial and lateral pterygoid nerves).
The pterygoid muscles are muscles of mastication and serve the movement of the temporomandibular joint. The contraction of the medial pterygoid elevates the mandible (jaw closure) and moves it forward (protrusion). These movements are reinforced by the muscle sling formed with the masseter. The lateral pterygoid differs from the other three muscles of mastication as it is the only one among them which can open the jaw. Once the mouth is opened with the help of this muscle, that movement is then continued with the help of the suprahyoid muscles. The bilateral activation of the lateral pterygoid causes also protrusion, whereas the unilateral contraction moves the mandible laterally (laterotrusion) and this way supporting chewing.
Temporomandibular joint disorders, such as crunching, popping or pain during chewing, are very often caused by tension of the jaw muscles. Usually both the masseter and temporal muscles are affected, whereas stiffnening of the pterygoid is relatively rare. Common causes for tension in the pterygoid muscles include abnormal occlusion, trauma, but also stress (e.g. during rage attacks or state of anxiety).