Muscles of Mastication – Anatomy Tutorial

Muscles of Mastication – Anatomy Tutorial


This is a tutorial on the muscles of mastication.
So the muscles of mastication are innervated by the trigeminal nerve. They’re innervated
by the mandibular branch of the trigeminal nerve. So that’s V3. When you’re testing the trigeminal nerve,
you’re testing muscles of mastication and facial sensation. So the muscles of mastication
are innervated by the mandibular branch of the trigeminal nerve. Most of the muscles
of facial expression are innervated by the facial nerve, cranial nerve seven. So the
trigeminal nerve is cranial nerve no. 5 and the muscles of mastication are innervated
by V3, so the mandibular branch. There are four muscles that you need to know
which are involved in mastication — the temporalis, the masseter, the medial pterygoid and the
lateral pterygoid. I’ll begin by showing you the temporalis muscle,
which is this muscle here, this big muscle which sits in the temple fossa of the skull.
So if I just show you the temple fossa, you can see this indentation on the lateral aspect
of the skull. This is where the temporalis sits. This muscle inserts — all the muscles of
mastication inserts onto the mandible because the mandible is the bone that moves to cause
mastication. It’s the bone which is involved in chewing. So the temporalis inserts onto the coronoid
process of the mandible. That’s this anterior process here. If we just have a look at that,
it just inserts here. If I just show you the other side, you can see that it inserts just
there, the coronoid process of the mandible. Just looking at the points of insertion and
its origin, you can see that if the muscles were to contract, it would cause the mandible
to elevate and it can pull it back in a posterior direction. If you just look at the direction
of the fibers so it also causes the mandible to retract. So there’s four important movements to know
with regard to the mandible. You’ve got retraction (that’s movement posteriorly), you’ve got
protrusion (that’s movement in this direction anteriorly) and you’ve got elevation (so bringing
the mandible upwards in a superior direction) and you’ve got depression (which brings the
mandible inferior). So four movements of the mandible. So looking at the origin and the insertion
of the temporalis muscle, you can see that it elevates it and it can also retract it
looking at the direction of the fibers. So if you put your fingers in the temple region
on your face and you clench your muscles as if you’re chewing, you can actually feel this
muscle working. When you’re testing the trigeminal nerves, this is what you do to your patients.
You put your fingers in the temple region and ask them to chew, grind their teeth, so
you can feel this muscle working. So if I just bring back the muscles that I
got rid of, this muscle here is the masseter. This is another muscle involved in mastication.
This muscle actually has two parts. It’s got a superficial part and a deep part, which
isn’t actually very clear on this model, but the deep part inserts a bit more posteriorly
in the zygomatic arch and the superficial part inserts more anteriorly on the zygomatic
arch. So if you remember my tutorial on the skull,
you’ve got this arch here, which is referred to as the zygomatic arch and it’s comprised
of the zygomatic process of the maxilla and the zygomatic bone. So the masseter has two parts — the deep
and superficial part which originates on the zygomatic arch. It inserts onto the lateral
aspect of the lateral surface of the ramus of the mandible. So again, this is a muscle
you can feel on yourself. If you put your fingers over the angle of your mandible and
clench your teeth together, you can feel this muscle working. So what this muscle does is it elevates and
retracts the mandible. It just elevates the mandible, it doesn’t retract the mandible. So the next two muscles of mastication are
the pterygoid muscles. You’ve got the lateral and the medial pterygoid muscles. These muscles
are called the pterygoid muscles because they insert onto the pterygoid process. So if you’ve
watched the tutorials on the skull, bones of the skulls, you’ll remember that the pterygoid
process is a process which extends downwards from the sphenoid bone. The lateral and medial
pterygoid muscles onto the lateral plate of the pterygoid process. So this is what I found a bit confusing. The
lateral pterygoid muscle is called the lateral pterygoid because it inserts onto the lateral
surface of the lateral pterygoid plate. The medial pterygoid muscle is called the medial
pterygoid because it inserts onto the medial surface of the lateral pterygoid plate. I’ll just show you this quickly on a different
model. We’ve got the temporalis here, the masseter. And then if I remove the masseter,
you can see there are some muscles that lie deep to the mandible. If I just rotate it
around, you can see on the inside surface of the mandible that there are two muscles.
Unfortunately, this model doesn’t actually have the medial pterygoid muscles, so what
we’re looking at here is the lateral pterygoid muscles. If I just show you from the outside,
you can see how they sit underneath the mandible on the interior surface. I’ll just swing it around again. What you’ve
got here are the lateral pterygoid muscles. There’s two parts. We’ve got the superior
lateral pterygoid and the inferior lateral pterygoid. So 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. So just to show you again. The pterygoid process
is this thing that’s pointing down. If I rotate it around, if you keep your eyes on this process
here, this downward pointing process, this is the pterygoid process. So if I just remove
the masseter and remove the mandible temporarily, you can see the pterygoid process sticking
down. So it’s this bone here, this thing sticking down. And you’ve got medial and lateral plate.
So you’ve got this medial plate here and you’ve got the lateral plate. So the pterygoid muscles originate on the
lateral plate, but the medial pterygoid (which isn’t shown here) inserts on the medial surface
and the lateral pterygoid inserts on the lateral process. This model isn’t entirely accurate
because this muscle isn’t showing to be inserting on the lateral plate, but in reality, it inserts
on this lateral plate of the pterygoid process. If I just get the mandible back, it inserts
onto the condyle of the mandible. So just to repeat that, you’ve got the pterygoid
process here, which is part of the sphenoid bone. You’ve got the lateral plate and the
medial plate. But the confusing thing is that the medial pterygoid doesn’t insert on the
medial plate (which is this thing here), it actually originates on the medial surface
of the lateral pterygoid plate and it inserts on the medial surface of the mandible. So that’s the medial pterygoid muscle, which
isn’t shown here unfortunately, but it originates on the medial surface of the lateral pterygoid
and it inserts onto the medial surface of the angle of the mandible. So the lateral pterygoid has two heads. It’s
got two muscles. It’s got the superior and inferior lateral pterygoid. 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. So those are the four muscles of mastication.
You’ve got the temporalis, the masseter (which is this muscle here) and you’ve got the medial
and lateral pterygoid muscles. So 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.

82 thoughts on “Muscles of Mastication – Anatomy Tutorial

  1. thnks a lot sir for posting this video…….it is very helpful ..plz keep on posting such videos…and make our studies easy

  2. sincere efforts are always appreciated…sooner or later…the amont of hardwork thats gone into this ….needs true appreciation..plz take care of contents also that r there in triangles..its a request..bye tc.

  3. No problem, I enjoy making them! I will definitely continue to produce them – I have just been extremely busy in the last few months and have had limited internet access, but look out for new tutorials in the near future! 🙂

  4. Just for your benefit, there are many sources which indicate that the lateral pterygoid inserts both onto the condyle of the mandible, as well as the articular disk. Their belief is that the pterygoid is helping to anchor the disk to avoid any pathological dysfunction where it might pop anteriorly over the condyle (as a result, defeating its purpose within the joint). H
    owever, this video was extraordinarily helpful. Thank you so much!!! It is really appreciated!

  5. omg!!!daz a awesome work …thanku so so so much sir… am preparing for pg, n it helps me a lot… expecting more n more… .plz keep updating ..

  6. would you please give me a download link to that model.. im really confused of not being able to find an anatomical skull in my town

  7. I love this video. 11 minutes you can understand the muscle of mastication VERY clearly. It totally worths. Though he repeated the same idea again and again, I never find him boring, instead, he is telling us not to confuse the origin and insertion. I would recommend this vid to everyone i know.

  8. There isnt that much to explain about 4 muscles… and if he only said it once you'd have to play it over and over again anyway, unless you remember every insertion and origin the first time you hear it, if so I envy you 🙂

  9. Well done: clearest animation yet on the lateral pterygoids. They are the bane of my nocturnal bruxism and daily muscle dysfunction.

  10. Sir, m from India.. And m preparing for my post graduate course in medicine.. Ur videos are extremely useful for my exams.. Thanks a lot .. Million and billion of thanks..I got a good orientation of human anatomy ..

  11. great video! not commonly talked about, but the mandible also has lateral movements during unilateral muscle activation

  12. great vids! couple of strange mistakes… you call the temporal process of the zygomatic bone the "zygomatic process of the maxilla". also you call the zygomatic process of the temporal bone the "zygomatic bone". (c. 4:25)

  13. Just for your information, you've confused us & also yourself about the insertion of Lat. & Med. Pterygoid mus. All muscles here should insert in Mandible. But no offense! I really appreciate your endeavor. Please carry on!!

  14. wait… masseter does adduction AND protrusion! also what about the unliateral conractions? just reviewed the vid now for my upcoming finals and allthough i usually really like your videos, this is not one of your best =( sorry to say that… but keep on doing this vids! thanks for your effort!

  15. It would help a bit more if you elaborated on how the lateral and medial pterygoids influence the TMJ and their action on bringing the jaw back to neutral at the end phase of mastication.

  16. love your videos man theyre awesome but this isn't your greatest one at least with respect to the pterygoid haha– its not really your fault though that model isn't exactly helping. if anyone is using this video for boards review id def recommend cross referencing a chart for the origins and insertions of the pterygoid muscles here. theres also some extra sort of minor actions that arent covered for some of the other muscles

  17. MISTAKE!!! 4:20
    temporal process of zygomatic and zygomatic process of temporal.
    NOT zygomatic process of MAXILLA
    thanks 4 the video 😉

  18. you forgot to mention the lateral pterygoid is the only depressor of the mandible! quite significant as its the only muscle out of the 4 which does that! and its the zygomatic process of temporal bone not maxilla!!

  19. Great series of videos but you always confuse insertion points with origins of muscles and I concur that coughing should be muted.

  20. this video was definitely not of AZ's standard. Informative but could have been so much better if there wasn't so much confusion about insertion origin.

  21. This was very very helpful ….can u please do some videos about embryology ..I find it really difficult to visualise.

  22. You forgot side to side movement. The muscles involved with side to side movement are, Medial pterygoid, Lateral pterygoid, Masseter and Temporalis.

  23. Mastication is the grinding and chewing of solid frod by the teeth.food is broken down into small pieces and mix with the saliva

  24. This 5:20 video is definitely better than this. Concise and accurate to the point. Please have a look : https://youtu.be/dx4mDmWPoUA

  25. u just confused me that wasn't helpful at all compared to the thousands of other videos when u search for this information

  26. Just for those reading the comments the zygomatic process of the maxilla along with the zygomatic arch for the origin of the masseter is right.

  27. Excellent video. You’ve summed up the basics in 12 minutes what I learned in a week long course. Great revision for me. Thank you so much for taking the time to post this.

  28. Haven't explained all the muscles, left out medial pterygoid diagrams Sorry buddy but it's thumbs down from me. Please edit and add , then it will be a 5 star video.

  29. THANK YOU SO MUCH!!! I'm a spanish speaker and I learned more here than in my class!! so thank you so much for share this with us!! hope you the best <3!!

  30. 4:21 temporal process of the zygomatic bone NOT zygomatic process of the maxilla
    4:24 zygomatic process of the temporal bone NOT zygomatic bone

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