While the jaw and your teeth are incredibly important in crushing food into a bolus, none of it would even happen—your mouth wouldn't even open —without the help of the muscles of mastication. Download this information and more! I'm going to work from the inside out. The muscles of deep mastication are few, but powerful.
There are only two of them: the deep masseter and the temporalis. These muscles, while "deep," are actually among the most "visible" of the mastication group, in that they aren't completely hidden by bone. Image from Muscle Premium. Elevates and retracts the mandible against the maxillae with great force. Mandible elevation involves both muscles working to bring the mandible back up toward the maxillae.
Remember, when you chew, it's only your jaw that moves; the maxillae remain fixed to the skull. The mandible is the only free-moving bone in the skull. Check out these muscle movements and more in Muscle Premium! The superficial muscles group is comprised of three muscles: the medial pterygoid, lateral pterygoid superior and inferior heads , and superficial masseter.
The medial pterygoid and superficial masseter are pretty straightforward, but the lateral pterygoid is an interesting little thing. It is one muscle but originates in two different locations. There are other muscles in the body that have two different origins, such as the biceps brachii, but the lateral pterygoid is the only one in the head region. Lateral pterygoid plate and the pyramidal process of the palatine. Ramus and angle of the mandible via a strong tendinous lamina.
Two heads: the superior from the sphenoid and infratemporal crest; the inferior from the lateral pterygoid plate. Condyle of the mandible and front margin of the articular disk of the temporomandibular articulation. Have you ever thrust your jaw out so your bottom teeth stick out in order to look like a bulldog? It's a face my youngest niece loves to make. If I just show you from the outside, you can see how they sit underneath the mandible on the interior surface. This superior lateral pterygoid originates on the infratemporal surface of the greater wing of the sphenoid and it inserts superiorly on the condylar process of the mandible.
This is the posterior process on the mandible. The inferior lateral pterygoid inserts a little bit lower on the neck of the condyle of the mandible. It originates on the lateral plate of the pterygoid process. Just to show you again. If I rotate it around, if you keep your eyes on this process here, this downward pointing process, this is the pterygoid process.
If I just remove the masseter and remove the mandible temporarily, you can see the pterygoid process sticking down. The lateral pterygoid has two heads.
The superior lateral pterygoid joins with the capsule of the temporomandibular joint higher up on the condyle of the mandible and the inferior lateral pterygoid inserts on the neck of the condyle of the mandible. Those are the four muscles of mastication. The medial pterygoid muscles are involved in elevation and side to side movements of the mandible. The lateral pterygoid is involved in protrusion and side to side movements of the mandible.
Skip to content. Muscles of Mastication Head Face and Scalp. Related Tutorials. Muscles of Facial Expression. Transcription There are four muscles of mastication. The pterygoid muscles can be confusing The pterygoid muscles are so-named, because they originate on the ptergoid process, which is a downward pointing process that extends from the sphenoid bone. The pterygoid process has two plates - a medial and lateral plate. The pterygoid muscles both originate on the lateral plate of the ptergoid process: The lateral pterygoid attaches to the lateral surface of the lateral pterygoid plate The medial pterygoid attaches to the medial surface of the lateral pterygoid plate Action Both pterygoids provide side to side movement of the jaw.
The lateral pterygoid also protacts the jaw. The medial ptergoid also elevates the jaw. If I just get the mandible back, it inserts onto the condyle of the mandible. Start typing and press enter to search Search ….
We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. Manage consent. It is split into two sections: alar and transverse. Corrugator Supercilii : A small muscle located superiorly to the orbicularis oculi. Orbicularis Oculi : A thin muscle that surrounds the eye socket. It acts to lift the upper lift and dilates nostril, producing a snarling expression. Chewing Muscles Mastication, or chewing, involves the adduction and lateral motions of the jaw bone.
Learning Objectives Differentiate between the actions of the masseter and the temporalis muscles in chewing. Key Takeaways Key Points The masseter elevates the jaw, closing the mouth. The temporalis elevates and retracts the jaw. The lateral pterygoid is the only muscle of mastication that actively opens the jaw. Unilateral action of a lateral pterygoid produces lateral movement in the jaw, usually performed in concert with the medial pterygoids.
The medial pterygoid elevates and closes the jaw, contributes to protrusion of the mandible, and assists in mastication. Key Terms medial pterygoid : A muscle of mastication with two heads. It lies inferiorly to the medial pterygoid. It lies superiorly to the medial pterygoid. Key Movements Elevation of the Jaw: Produced by the masseter, temporalis and medial pterygoid.
Depression of the Jaw: Produced by the lateral pterygoid, assisted by the digastric, mylohyoid and geniohyoid muscles found in the neck. Protraction of the Jaw: Produced by the lateral pterygoid. Retraction of the Jaw: Produced by the temporalis. Lateral Movement of the Jaw: Produced by the lateral and medial pterygoid. Neck Muscles Cervical muscles are those associated with the front of the neck; vertebral muscles are associated with the vertebral column. Learning Objectives Outline the neck muscles and their movements.
Key Takeaways Key Points Numerous muscles contribute to the processes of speaking and swallowing. These muscles can be divided into suprahyoid and ingrahyoid groups based on their locations relative to the hyoid bone. The hyoid bone, located beneath the mandible, acts as a key attachment point for muscles involved in speaking and swallowing. Numerous muscles contribute to both the stabilization and fine movements of the head and neck.
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