Musculus pterygoideus
Deep jaw muscles on the medial side of the mandible. The medial pterygoid assists in jaw closing, while the lateral pterygoid is crucial for the side-to-side grinding motion unique to herbivore mastication.
Origin: Pterygoid bone and palatine bone of the skull
Insertion: Medial surface of the mandible (angle and ramus)
Action: Medial: closes the jaw. Lateral: protrudes and laterally deviates the mandible for grinding
Innervation: Mandibular branch of the trigeminal nerve (CN V3)
Inflammation or misalignment of the temporomandibular joint causes secondary spasm and atrophy, often linked to dental issues or poor bitting.
Inflammation or misalignment of the temporomandibular joint causes secondary spasm and atrophy, often linked to dental issues or poor bitting. Signs include: Reluctance to chew; quidding; head tossing; resistance to the bit; tenderness over the temporal fossa; visible muscle wasting above the eye.; Consult veterinarian for specific symptoms.; Difficulty chewing; quidding (dropping food); pain on palpation in front of the ear; clicking or popping sounds during chewing; asymmetric jaw movement.; Clicking or popping sounds when chewing; reduced jaw excursion; aversion to hard feeds; head rubbing against objects.; Clicking or popping at the TMJ during chewing; reluctance to chew on one side; dropping feed; head tilt while eating; pain on palpation of the TMJ.; Difficulty accepting the bit; mouth opening or crossing the jaw; head tossing when contact is taken; pain on palpation of the jaw angle; may accompany dental hooks or wolf teeth issues.
See the Pterygoideus on our interactive 3D horse model. Open 3D Model