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In this video, I go through the Muscles of Mastication, covering their origin, insertion, and function. Understanding these muscles is essential for comprehending jaw movements and chewing mechanics.
Introduction
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Hey, what’s up. Meditay here and this.. is my first video of the muscular anatomy series.
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So in this segment, we’re gonna cover all muscles of mastication. Which are a part
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of the muscles of the head. Alright so All muscles of the head are divided into
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two groups. The first group is the muscles of mastication. Mastication means to chew,
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so those are the muscles responsible for chewing when you’re eating. And the second group is gonna
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be fascial muscles or the muscles that are gonna be responsible for facial expression. So
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we’re gonna focus on the mastication muscles here. So in this video, we’re gonna cover the origin and
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insertion points of the 4 muscles of mastication, which are the Temporal, Masseter, Medial
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Pterygoid, and Lateral Pterygoid muscles. And then in the next video, we’ll cover the facial muscles.
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Alright. Before we start, I want you to have some basic understanding
Parts of Skeletal Muscle
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of what makes up the different parts of a muscle. All the muscles in our body consist of an Origin
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point, which is the part of the muscle that’s attached to a bone that does not move or move
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a very slightly bit during contraction. It has a head, which is the proximal part of the muscle,
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there’s a belly which is the widest part of the muscle. Then there’s a tail and an Insertion
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point, which is the part of the muscle that’s attached to a bone that moves during contraction.
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When you’re studying muscles in general, the origin and insertion points are what we
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usually focus on. And again keep in mind that the origin point is the least movable part,
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and the insertion point is the part of the bone that is moved during contraction.
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In some locations you’ll also see the word belly, usually if the muscle is divided into two parts,
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that’s when we mention this term. Awesome. Let’s now cover the muscles of mastication.
Muscles of Mastication
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The muscles of mastication again, consist of the temporal muscle. Masseter muscle, Medial Pterygoid
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muscle, and Lateral Pterygoid muscle. So when the next time you take a bite of that burger,
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these are the muscles that help us mechanically grind through the food inside of our oral cavity.
Temporal Muscle
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Alright. So the Temporal muscle looks like this. It originates from the Temporal Fossa which is the
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fossa located on the temporal bone, and it also originates from the inferior temporal line on the
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parietal bone. The fibers then go down behind the zygomatic arch as you see here, and attach to the
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coronoid process of the mandible. Which is here. And so what are the functions of this muscle?
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When the anterior fibers contract, they elevate the mandible. And when
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the posterior fibers contract, they retract the mandible as you see here. So that is that one.
Masseter Muscle
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Next, we have the Masseter muscle, which is this one. If you look closely, you’ll see that
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it consist of a superficial part and a deep part. But they both originate from the same structure.
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The superficial part originates from the anterior part of the zygomatic arch, while the posterior
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fibers originate from the posterior part of the zygomatic arch. Fibers are then inserted at the
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Masseteric tuberosity of the mandible. And when these fibers contract, they Elevate the mandible.
Medial Pterygoid Muscle
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Next, we have the Medial pterygoid muscle, and to see this one,
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we need to look at the head from this perspective. So the medial pterygoid muscle is located on the
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other side f the masseter muscle. And what are the origin points? If we zoom in, you’ll see that
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it has a superficial part and a deep part. The superficial part originates from the Maxillary
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tuberosity, and the deep part originates from the Pterygoid Fossa of the Pterygoid Process.
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These fibers go down and insert at the Pterygoid tuberosity of the Mandible.
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The function of this muscle is either elevation of the mandible if both the right and the left medial
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pterygoid muscles contract. And if only one side contracts, they move the mandible in a frictional
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masticatory movement. A grinding movement kinda. Then lastly, we have the Lateral pterygoid muscle.
Lateral Pterygoid Muscle
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Which is located laterally to the medial pterygoid muscle. So if we go back to this view and remove
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all the muscles, and then you remove the mandible, we’ll be able to see this muscle very easily.
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And so this muscle is also divided into two parts. Itæs divided into a superior head,
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which originates from the infratemporal surface as well as the sphenoid bone.
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And an inferior head, which originates from the Lateral lamina of the pterygoid process.
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These two heads kinda join together to insert into a common area, at the pterygoid fovea
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of the mandible, which is here. Here. The function of this muscle is to move
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the mandible forward if both the right and the left side contract together,
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or produce a frictional masticatory movement if only one side contracts.
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So that was all I had for the muscles of mastication.
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