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Lines of traction of the lateral pterygoid muscle. Muscles of the head

The chewing muscles are so named because they are involved in the complex process of mechanically grinding food. They also provide movement of the lower jaw. Due to this, a person can close and open his mouth, talk, yawn, etc. The chewing muscles are fixed on the bones in the same way as others. They are fixed with two ends. The movable part of the muscles is fixed on the lower jaw. The motionless one is fixed on the bones of the skull. All muscles involved in chewing food and moving the lower jaw have a normal structure. They have a muscular part. It can contract and move the lower jaw.

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There are much less than, for example, mimic ones. There are four of the first ones. However, they perform the most important functions, including ensuring the preservation of the "corner of youth". These include muscles:

  1. Temporal.
  2. Chewable.
  3. Lateral and medial pterygoid.

All these elements form a single structure. With shortening or deformation of one of them, the rest undergo changes as well.

Lateral pterygoid muscle: photo, short description

It has two heads. They are separated by their own connective membrane (fascia). The lateral pterygoid muscle starts from the bone at the base of the skull. In this case, the beams move away from different points. The narrower (upper) protrudes from the infratemporal region of the greater wing in the sphenoid bone, as well as from the infratemporal ridge. The wider (lower) bundle comes out from the side. It starts from the pterygoid lateral plate in the fibers unite upon reaching the attachment point.

Lateral pterygoid muscle: functions

It should be said that this muscle element has a variety of connections with other facial structures. If l atheral pterygoid muscle will begin to function poorly or will undergo deformations, this may affect the activity of other systems. Dysfunction of this element can cause the development of a variety of symptoms and disorders, including hearing loss. Lateral pterygoid muscle provides jaw extension. This is achieved by simultaneous contraction of the beams on the right and left. If only one side is engaged, the jaw moves in the opposite direction. For example, when the right bundle contracts, it moves to the left, and vice versa.

Medial element

This muscle is presented in the shape of a quadrangle. She acts as essential element mandibular ligament. The muscle is located on the inner surface of the bone, opposite the chewing bone, in the same direction with it. In some cases, their bundles are connected. The element is fixed with thick processes. There are two of them. The larger one is attached to the pterygoid lateral part in the sphenoid bone, the smaller one - at the pyramidal process in the palatine part and the tubercle on the bottom, the muscle is also fixed at two points. Many important structures are formed between the processes. Among them are nerves, alveolar, maxillary vessels. The medial element, as well as, provides the movement of the lower jaw. When contracting on both sides, the bone moves forward and upward, on one side - to the side.

Chewing element

This muscle is located on top of the pterygoid (medial and lateral). She is quite strong because she trains more often than others while chewing. Its contours are quite well felt, especially when it is in a contracted state. The muscle is fixed on the zygomatic arch. It has a rather complex structure. are divided into deep and superficial parts. The latter departs from the middle and anterior sections of the zygomatic arch. The deep part is attached a little further. It departs from the back and middle sections of the arc. The surface feature angles back and down. In doing so, it covers the deep part.

Temporal element

This muscle departs from three bones at once. The temporal element occupies almost 1/3 of the surface of the skull. In its shape, the muscle resembles a fan. The fibers are directed downward and pass into a rather powerful tendon. It is fixed on the lower jaw. This muscle provides biting movements. In addition, she pulls the lower jaw forward, and also raises it until it closes with the upper one. The temporal jaw does not have a pronounced relief. However, she is directly involved in the formation of "sunken temples". With weight loss or frequent nerve stress, the muscle takes on a thinner and flatter shape. The temporal line and zygomatic arch at the same time acquire a relief. It is in this case that the face looks emaciated. With dysfunction or spasm, it is very difficult to detect changes in it.

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Chewing muscles

The chewing muscles get their name from the fact that they are involved in complex chewing processes. They are actively involved in the movement of the lower jaw, thanks to which we can tear off and close the mouth, push the lower jaw forward and return it to starting position, do lateral movements of the lower jaw back and forth, yawn and talk!

The chewing muscles have one feature - they are attached to the bones in the same way as the muscles of the trunk - with two ends to the bone structures. The movable point of one end of the masseter muscle is attached to the lower jaw, and the fixed point is fixed to the bones of the skull. The chewing muscles have the usual structure of muscle that can contract and move the lower jaw.

The chewing muscles are much smaller than the facial muscles - there are only four of them, but they play a major role in maintaining a youthful face contour and maintaining a "youthful angle". Let's list these muscles:

Consideration of the masticatory muscles from the point of view of interaction, rather than a separate existence, is key not only in the process of studying anatomy, but also in further self-modeling of the face.

1. LATERAL (Lateral) Pterygoid Muscle

As shown in the figure, the lateral pterygoid muscle is not one, but two muscles (heads), separated by their own fascia (connective membrane). Both bundles originate at the base of the skull on the sphenoid bone, but not at one point, but at different ones. So, the upper (narrower) bundle of the lateral muscle protrudes from the infratemporal surface of the greater wing of the sphenoid bone and from the infratemporal crest. The lower (wider) bundle emerges from the lateral pterygoid plate of the sphenoid bone. The union of the fibers of the two bundles into a short and thick tendon occurs when they reach their place of attachment. The connections of this muscle with other structures of our face are so wide that its dysfunction can cause a wide variety of symptoms, even including hearing problems.


Rice. 1. Lateral pterygoid muscle

The lateral pterygoid muscle performs a very important function - while contracting the muscles of the right and left sides, we can extend the jaw. If the muscle of one of the sides contracts, then lower jaw moves in the opposite direction.

2. MEDIAL Pterygoid Muscle

The medial pterygoid muscle is in the shape of a quadrangle and is a very important component of the mandibular ligament. It is located on the inner surface of the lower jaw. The medial pterygoid muscle is also located in the same direction as the masseter muscle and is attached opposite this muscle. Sometimes individual bundles of the medial pterygoid muscle are connected to muscle fibers chewing muscle.

The medial pterygoid muscle is attached to the bone by two thick processes. The larger process is attached to the lateral pterygoid part of the sphenoid bone. Smaller in size - at the pyramidal process of the palatine bone and the tubercle of the upper jaw. The muscle is attached by two processes to the lower jaw.

Many important structures are formed between these two processes of the medial pterygoid muscle, including the maxillary, alveolar blood vessels and nerves. ... At the superior border of the muscle, the tympanic tendon nerve connects to the lingual nerve.

The medial pterygoid muscle, as well as the lateral muscle, when contracted from both sides, pushes the lower jaw forward, simultaneously lifting it. In case of muscle contraction on one side of the face, the lower jaw moves in the opposite direction.


Rice. 2. Medial pterygoid muscle

3. CHEWING MUSCLE

Unlike the entire group of masticatory muscles, the masticatory muscle is the most superficially located. Like a blanket, it covers the structure of the medial and lateral pterygoid muscles. The chewing muscle is very strong because we have the ability to train it while chewing. The contours of the masseter muscle are very clearly visible and very easy to feel, especially when the muscle is in a contracted state. The chewing muscle attaches to the zygomatic arch and has a complex structure. Its muscle fibers are divided into two parts - superficial and deep. This is clearly seen in the figure:


Rice. 3. Chewing muscle

The superficial part starts from the anterior and middle sections of the zygomatic arch. The deep part begins a little further - from the middle and posterior parts of the zygomatic arch. The surface part runs at an angle backward and downward so that it covers the deeply located part.

Both parts of the muscle are attached to the lateral side of the lower jaw, along its entire length, as well as to the jaw examination.

4. The temporal muscle

The temporalis muscle originates from three bones at once - the frontal, parietal and temporal. The temporalis muscle occupies almost 1/3 of the entire surface of the skull and is very much like a fan in shape: broad muscle fibers, going down, pass into a powerful tendon, which is attached to the coronoid process of the lower jaw.

One of the amazing abilities of the temporalis muscle is that it can only contract a certain set of fibers at a time. That is, the anterior, median or posterior parts of the temporalis muscle are able to make contractions without the participation of each other.

The temporalis muscle participates in biting movements, pulls back the extended jaw, and also raises the lower jaw until the upper and lower jaws close.

The temporalis muscle does not have a pronounced relief, but is directly involved in creating the image of the "sunken temples". When a person loses weight, or exposes himself to severe nervous stress, the temporalis muscle becomes flatter and thinner. Contrasting with it, the zygomatic arch and the temporal line acquire the relief. It is then that the temporal fossa becomes more noticeable, and the face takes on an expression of exhaustion.

We continue to study the anatomy of the muscles of the head, now it is the turn to disassemble the chewing muscles. We will follow the same principles as in other articles on anatomy - first we will highlight the main landmarks and then remember the special signs of each muscle. I hope that with my lessons anatomy will be easier for you.

Features of the chewing muscles:

  1. All chewing muscles attach to the mandible (mandibula);
  2. All chewing muscles raise the lower jaw, chewing and promoting correct pronunciation words;
  3. The chewing muscles, in contrast, have fascia.

These features are not indicated in atlases and textbooks, and, as a rule, they are not required to be named on tests. I brought them specifically to make it easier for you to navigate - as soon as it comes to any chewing muscle, you immediately understand that it attaches to the lower jaw and raises it. That is, the name of a muscle group alone is enough to remember the function and place of attachment.

Chewing Muscles Anatomy:

I. Temporalis muscle(musculus temporalis)

The largest and most prominent chewing muscle. Unlike all other masticatory muscles, its abdomen is located on the vault of the skull (fornix cranii).

In green, I highlighted the contour of the temporalis muscle itself, in blue - the contour of a powerful tendon, with the help of which the muscle is attached to the coronoid process (processus coronoideus) of the lower jaw. I circled the coronoid process in yellow, I hope you remember it from craniology. When you show the location of the temporalis muscle in the test, you should trace the entire contour as a whole, that is, both the muscle and its tendon.

The temporalis muscle is located in the temporal fossa (fossa temporalis). If you take a prepared skull or even a high-quality artificial specimen, you will see depressions on its sides. These impressions are shallow, but occupy a large area. It is these impressions that are called temporal fossa. In the picture from Wikipedia, the temporal fossa is highlighted with a black frame:

Start: The temporalis muscle begins on the temporal surface of the frontal bone, as well as on the squamous surface of the temporal bone.

Attachment: The temporalis muscle attaches to the coronoid process of the lower jaw (the sharpest process of the lower jaw). Do not forget that the chewing muscles start from the stationary part, but attach to the bone that they move.

Function: the temporalis muscle closes the mouth, raising the lower jaw to the state of closed teeth. Also, if you push the lower jaw forward, like a box in a table, then it is the temporalis muscle that will push it back into its normal position.

II. Chewing muscle(musculus masseter)

It is also a very visible and large muscle. If we are looking at a tablet with a picture in profile, it is impossible to confuse the chewing muscle with anything. See:

The chewing muscle is extremely important for survival, therefore, in our distant ancestors, this muscle was formed very powerful and strong. The chewing muscle consists of two parts - superficial (pars superficialis) and deep (pars profunda). You can easily distinguish the superficial part - it attaches to the front of the zygomatic arch (arcus zygomaticus). The deep part is also attached to the zygomatic arch, only not in front, but behind.

I have highlighted the surface with a green outline, and the deep with blue:

Start: both parts of the masseter muscle begin from the zygomatic arch.

Attachment: both parts of the masseter muscle are attached to a special place on the lower jaw - to the masticatory tuberosity (tuberositas masseterica). Chewing tuberosity, recall, is located on outer surface branches of the lower jaw (ramus mandibulae).

Function: raise the lower jaw, chewing and helping the pronunciation of words. Also, the superficial part of the masseter muscle helps to push the jaw forward. We will push it back with the help of the temporal muscle, as you remember.

III. Lateral pterygoid muscle(musculus pterygoideus lateralis).

Now we need a tablet with a skull, which we look at as if from the inside of the mouth (cavitas oris). Something like this:

We turned the skull with the back of the head towards us and sawed it in the frontal plane so as to look from the inside at the oral cavity, gums and teeth.

Let's look at the lateral pterygoid muscle. Here we can see both lateral pterygoid muscles, so I have highlighted both:

The lateral masseter muscle has two parts - upper and lower.

a) Top part.

Start: The infratemporal crest of the large wing of the sphenoid bone. Let's remember the sphenoid bone (os sphenoidale) - it has a body (corpus), large wings (alae majores) and small wings (alae minores), as well as pterygoid processes (processus pterygoidei).

For some reason, many people like to confuse large wings and pterygoid processes. Let's look at a simplified diagram (front view) so as not to confuse these anatomical structures:

We are interested in the large wing. It is on it that the small infratemporal ridge (crista infratemporalis) is located. This is where the top of the lateral pterygoid begins:

Attached top part lateral pterygoid muscle to the temporomandibular joint (articulatio temporomandibularis).

b) Bottom part the lateral pterygoid muscle begins from the sphenoid bone, too. Now we need to move our attention from the large wing just below - to the pterygoid process (processus pterygoideus). It is, as it were, split into two plates - medial and lateral. Look at the penultimate picture - there I highlighted the pterygoid processes in brown.

Let's find the lamina lateralis of the pterygoid process. This is, in general, not difficult:

It is from this plate that the lower part of the lateral masseter muscle begins.

So the beginning: lateral muscle(its lower part) starts from the lateral plate. Excellent memory, by the way.

Attachment: pterygoid fossa (fovea pterygoidea) of the lower jaw. Not a very well-known anatomical formation, so I found this diagram:

Our pterygoid dimple is numbered 4.

The function of the lateral pterygoid muscle is to raise the jaw (as in all masticatory muscles), as well as to abduct the lower jaw to the opposite side of the muscle. For example, the left lateral pterygoid muscle, when contracted, shifts the lower jaw to the right side.

IV. Medial pterygoid muscle(musculus pterygoideus medialis). Let's take a tablet we already know to look at this muscle:

Start: Pterygoid fossa (fossa pterygoidea) of the sphenoid bone. By the way, as you remember, the lower jaw also has a pterygoid fossa, only it is called fovea pterygoidea, so as not to be confused. Ancient anatomists are very forward-thinking guys, definitely.

To be honest, I find it difficult to show it on a tablet. At the time of this writing, I don't have the skull at hand, but the respected Sinelnikovs in their atlas indicate that "... the medial and lateral plates limit the pterygoid fossa." At the same time, in the illustration closest to the text, fossa pterygoidea is indicated on the lateral plate (two pictures ago, I highlighted the lateral plates of the pterygoid processes in red). The Sinelnikovs are right anyway - they are the kings of anatomy, nevertheless. To you, dear readers, I advise you to ask your teachers about the location of this hole on occasion.

In general, speaking about the beginning of this muscle, we focus on the lateral plates of the pterygoid processes of the sphenoid bone and clarify about the fossa from the teachers.

Attachment: pterygoid tuberosity of the lower jaw. There will be no difficulties here, here is where this place is:

Function : Raising the lower jaw, as well as "pushing" the lower jaw in the opposite direction (that is, similar to the lateral pterygoid muscle).

Lexical minimum

  1. Mandibula;
  2. Musculus temporalis;
  3. Fornix cranii;
  4. Processus coronoideus;
  5. Fossa temporalis;
  6. Musculus masseter;
  7. Arcus zygomaticus;
  8. Tuberositas masseterica;
  9. Ramus mandibulae;
  10. Musculus pterygoideus lateralis;
  11. Cavitas oris;
  12. Os sphenoidale;
  13. Alae majores;
  14. Alae minores;
  15. Processus pterygoidei;
  16. Crista infratemporalis;
  17. Articulatio temporomandibularis;
  18. Lamina lateralis;
  19. Fovea pterygoidea;
  20. Musculus pterygoideus medialis;
  21. Fossa pterygoidea.

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Chewing Muscle Anatomy: 8 comments

  1. Anastasia

    good day
    Thank you very much for your hard work.
    Each article is very valuable to me
    I am 33 years old and I entered the 2nd course of honey after college
    I work, I have a family, a child)))
    I'm worried - will I pull up to study)))
    Can't give you a list - at least for the 2nd and 3rd year - which textbooks are better for teaching - biochemistry, hista, physiology, and so on?

    And do not tell me - who came to the 2nd year - pass anatomy and histology in the first session? We can say that there is no knowledge in these subjects. And the program of the 1st course - for self-study?

    1. Pavel Post author

      Good afternoon, dear Anastasia. Thanks for the nice review)

      I'll tell you a secret (just not a word to anyone), I myself entered the medical university far from after school. Well, I am learning slowly, I go on duty, I even manage to keep this blog in time. I think you also have the right approach everything will work out.

      Now about the right approach. Regardless of what kind of doctor you want to become, you need to be very confident in anatomy, histology, and bioorganic chemistry.

      1. Anatomy. If a person does not know anatomy, he should not work as a doctor, this is an axiom. If you do not know anatomy at all, you need to go through and learn all its sections: osteology (bones), arthrology (joints), neurology (CNS), splanchnology ( internal organs and systems), angiology (vessels, very difficult section), neurology (peripheral nervous system + autonomic), in that order. It will be extremely difficult for atlases and textbooks alone.
      But there is good news. Video tutorials on YouTube, which are freely available there, will greatly facilitate your task. Personally, I and the most successful guys from my stream passed the anatomy just like that. I recommend that you start with the lectures of Professor Izranov (I will never tire of praising him). He is a recognized authority on the Russian anatomical school and the creator of brilliant video tutorials. They will definitely help you. You can find others good lessons on anatomy through a search on YouTube, but you definitely will not pass by Professor Izranov. I told you how to teach anatomy, and advice should also help you.

      2. Histology. There is general histology and private histology. From the general section it is necessary to know the structure / classification of the following types of tissues: epithelial; connective (this also includes blood), nervous, muscular. The first two are especially important.

      From the private it is necessary to know the structure and functions of the endocrine, hematopoietic (it is also immune), digestive, respiratory, nervous systems.

      About drugs: it is necessary to be able to confidently and quickly distinguish a hollow organ from a tubular, epithelial tissue from a connective tissue.

      The textbook I can only recommend is the one by which I myself studied, the author is Danilov. The same author has published a very good atlas. I must say right away that the textbook did not suit me very well, if it were not for the lectures of my teacher, it would be hard for me.

      Histology is very, very closely intertwined with normal physiology. The good news: if you know histology well, physiology will be much easier for you. Bad news: I did not find any histology lessons on YouTube, I have to use a textbook and an atlas. Maybe there is something now.

      3. Biochemistry. You asked about biochemistry, but biochemistry will be quite incomprehensible without a previous course in organic chemistry. I will share my observation - a lot of guys who, like you, entered the university after medical college, have very little knowledge of general school chemistry (the basics of inorganics + the basics of organic matter). If suddenly this is not about you, feel free to skip this item, with biochemistry you will be fine. If your chemistry is weak + HOC on the 1st course you missed, you must first go through the basic part of inorganics, then the basic part of organic, then get acquainted with the course of HOC.

      Here again YouTube will help us. Come to the channel of Vurdikhan Vurdikhanov, watch and take his lessons for those parts of the school course in which you are weakest. Unrealistically cool teacher. Then use your regular school chemistry textbook (Gabrielyan is quite good). The fact is that the HOC course, without which biochemistry will be difficult to understand, is almost entirely based on the school course of general chemistry.

      Don't take HOC lightly. Those students who try to understand and teach HOC, and then biochemistry, have a very large advantage in pathophysiology, pharmacology, and other fundamental disciplines.

      The Khan Academic YouTube channel will also help you a lot with biochemistry. Many important things are considered there - for example, lipid metabolism, the Krebs cycle, cellular respiration, and so on. I almost forgot, the Krebs cycle is considered on my site)

      4.Physiology. Check out my article on functional stress testing. There I briefly described how to work with normal physiology. However, I will add one thing that I forgot to write there. If you can get hold of Dr. Najeb's lectures (this is a very cool English-speaking physiologist and pathophysiologist) with a translation into Russian (or in the original, if you understand English fluently), you will be very very cool in everything related to physiology.

      PS. There is a lot of material, but do not hang your nose. Go through everything in stages, sketch and record lectures from the resources that I threw you. Medical college students at universities have a huge plus - they own a lot of manipulations and know nursing very well. Approach fundamental subjects methodically and comprehensively, study regularly and go through the topics of these subjects for at least 1.5-3 hours a day and everything will be great for you.
      Good luck to you)

    2. Oksana

      Good afternoon, Pavel! I am very glad that somehow miraculously came out to your "medical blog". For me, the topic of a quick study of anatomy by the systems of bone-muscles-nerves-vessels is now very relevant. I am already quite years old, and when I was going through anatomy at the school, I never thought that after 20 years I would need it practically in the institute's volume. You, oh, very competently, captivatingly and clearly describe everything, and I was very inspired by this. Tell me, do you have a honey page in VKontakte, or just this blog? And I wish you had the strength, time and mood to present other materials in the same way.

    3. Inna

      How nice that there are not so many 18-year-old students here))) I'm 26, also in my first year, also after medical college. I adore studying, I am friends with teachers, it is a little easier for me to study because I understand why I am here, I see the goal and go to it. Anyone who wants to enter - do it) a completely different approach to learning and the teachers see this, therefore they are better and loyal.
      In my university there are many who are not 18 years old, there is a man who is 40 and a woman who is 47! And we are all in the first year!
      Thank you very much for the article, you explain it very cool!

CHEWING MUSCLES- a group of muscles, the contraction of which shifts the lower jaw in the directions that provide chewing. Topographically, this muscle group includes some of the muscles of the head (actually the masseter, temporal, lateral and medial pterygoid muscles - Fig. 1) and the muscles of the neck located above the hyoid bone (maxillary-hyoid, sublingual and digastric muscles).

Anatomy

The masseter muscle itself(m. masseter) lies on the outer surface of the branches of the lower jaw; consists of three parts: superficial, intermediate and deep. The superficial part (pars superficialis) begins with a tendon from the lower edge and inner surface of the zygomatic arch, goes down and attaches to the chewing tuberosity of the lower jaw. The intermediate part (pars intermedia) starts from the inner surface of the zygomatic arch and from the anterior slope of the articular tubercle of the temporal bone, goes down and back, attaching to the outer surface of the lower jaw branch. The deep part (pars profunda) starts from the inner surface of the zygomatic arch and bone, attaching to the tendon of the temporal muscle. The function of the chewing muscle: the superficial part pushes the lower jaw forward, the intermediate and deep ones raise it.

Temporalis muscle(m. temporalis) lies in the temporal fossa, fan-shaped starting from the site of the bone, from the temporal surface of the large wing and the infratemporal crest of the sphenoid bone, from the parietal, scales of the frontal and temporal surfaces of the zygomatic bones and is attached by a powerful tendon to the coronoid process and branches of the lower jaw in the region mandibular notch and oblique line. The function of the temporal muscle: the anterior and middle bundles raise the lower jaw, the posterior ones pull it back.

Lateral pterygoid muscle(m. pterygoideus lat.) of a triangular shape lies in the infratemporal fossa. It starts with two heads: top and bottom. The upper head starts from the infratemporal surface and infratemporal crest of the large wing of the sphenoid bone, goes backward, attaching to the articular bursa and the articular disc of the temporomandibular joint. The lower head starts from the outer surface of the pterygoid process of the sphenoid bone, goes back and up, connects to the upper head and attaches to the pterygoid fossa on the neck of the lower jaw. Its function: with bilateral contraction, it pushes the lower jaw forward, with unilateral contraction, it shifts it in the opposite direction.

Medial pterygoid muscle(m. pterygoideus med.) of a quadrangular shape lies on the inner surface of the branches of the lower jaw. It begins with tendon and muscle fibers from the pterygoid fossa of the pterygoid process of the sphenoid bone, goes back and down, attaching to the pterygoid tuberosity of the lower jaw. Function: with bilateral contraction, it raises the lower jaw, with unilateral contraction, it shifts it in the opposite direction.

Maxillofacial muscle(m. mylohyoideus) flat, trapezoidal. It begins on the inner surface of the lower jaw along the maxillary-hyoid line. Muscle fibers are directed from top to bottom, from outside to inside and from front to back to the midline, where they form a tendon suture. Attaches to the body of the hyoid bone.

The sublingual muscle(m. geniohyoideus) triangular; starts from the chin spine of the lower jaw, goes down and posteriorly, attaching to the body of the hyoid bone.

Digastric(m. digastricus) has two abdomens: the back (venter post.) starts from the mastoid notch of the temporal bone and the front (venter ant.) - from the digastric fossa of the lower jaw; they connect into one intermediate tendon that attaches to the great horn of the hyoid bone. The function of the maxillary-hyoid, sublingual and anterior abdomen of the digastric muscle is that when the hyoid bone is fixed, they lower the lower jaw.

Depending on the function of Zh. M., Providing chewing (see), can be subdivided into three groups: lifters, extenders and lowers. The elevators include the actual chewing, temporal and pterygoid muscles, the lateral pterygoid muscles are the protractors, and the maxillary-hyoid, chin-hypoglossal and digastric muscles are referred to the descents. Blood supply - from the branches of the infratemporal part of the maxillary artery, the branches of the facial and lingual arteries.

Innervation of the chewing muscles occurs due to the third branch of the trigeminal nerve (n. mandibularis) and the facial nerve (n. facialis)

Pathology of the chewing muscles

The pathology of the masticatory muscles can manifest itself in the form of a dysfunction - paresis, paralysis; for example, with damage to the trigeminal nerve or its nucleus, atrophic paralysis of the femur is observed. With unilateral damage to the trigeminal nerve, chewing is difficult, but possible due to the healthy side. With bilateral atrophic paralysis of the stomach, chewing is impossible, the lower jaw sags. Such a picture can be observed in amyotrophic lateral sclerosis, when the pyramidal pathways and nuclei of the motor cranial nerves are affected. The defeat of Zh. M can be with tick-borne encephalitis. Function of Zh.m. is sharply disturbed and with trismus (see) - tonic spasm of Zh.m., which can be caused by an inflammatory process in the lower jaw or in soft tissues, adjacent to the area of ​​location or attachment of the femoral m. Spasm of the femoral m is a characteristic symptom in tetanus, can be observed with meningitis, in some cases - as a hysterical reaction.

Hypertrophy of Zh. M is observed rarely, while unilateral hypertrophy of m is more common. masseter. There are so-called. true and false hypertrophy of m. masseter. False hypertrophy is the development of lymphoid tissue or vascular tumor in the area of ​​the masseter muscle. True hypertrophy of Zh. M is insufficiently studied. Occasionally, it is observed with a violation of the bite. Clinically, hypertrophy is manifested only by a violation of the configuration of the face (Fig. 2); on the side of hypertrophy, the shape of the angle of the lower jaw can also be changed. It is necessary to differentiate true hypertrophy with benign neoplasms in the area of ​​the stomach (lymphoma, lipoma).

F. m. Are involved in patol, the process with injuries of the jaws, wounds of the face, specific inflammatory processes (actinomycosis), as well as with malignant tumors on the face.

Treatment

Treatment of patol, conditions of J. of m. Consists in the treatment of the underlying disease (infectious disease nervous system, injuries, tumors); with true hypertrophy of the so-called masseter - orthodontic treatment (see. Orthodontic methods of treatment) in order to eliminate bite anomalies; with pronounced hypertrophy, leading to facial asymmetry, partial surgical excision of the hypertrophied muscle is possible; upon detection of a tumor localized in the area of ​​the stomach, - appropriate treatment.

Bibliography: Vorobiev V. and Yasvoin G. Anatomy, histology and embryology of the oral cavity and teeth, p. 119, M., 1936; Gorenstein Ya. I. About hypertrophy of the masticatory muscles, Dentistry, no. 4, p. 87, 1965; Ivanitsky M.F. Human Anatomy, vol. 1, p. 379, M., 1965; L er N er I. O. Hypertrophy of chewing muscles, Stomatology, No. 2, p. 40, 1960, bibliogr .; Limberg A. A. Vascular tumor with multiple stones in the thickness of the masseter muscle, ibid., No. 4, p. 90, 1965; Morphology of the maxillo-mandibular apparatus, Proc. symp. 9-th. Int. congr. Anat., Lpz., 1972; S i h er H. Oral anatomy, St Louis, 1965.

H. H. Mosolov, B. M. Bezrukov.

1. Chewing muscles: derivatives of the first branchial (mandibular) arch, innervated by n. trigeminus.

2. Mimic muscles or facial muscles derivatives of the second branchial (hyoid) arch, innervated by n. facialis.

3. Muscles of the cranial vault.


Chewing muscles

The four chewing muscles on each side are genetically connected (they originate from one branchial arch - the mandibular), morphologically (they all attach to the lower jaw, which they move during their contractions) and functionally (they perform chewing movements of the lower jaw, which determines them location).

1.M. masseter,chewing muscle starts from the lower edge of the zygomatic bone and zygomatic arch and adheres to the tuberositas masseterica and to the outer side of the ramus of the lower jaw.

2. M. temporalis, temporal muscle, its wide beginning occupies the entire space of the temporal fossa of the skull, reaching up to the linea temporalis. The muscle bundles converge in a fan-like manner and form a strong tendon that fits under the zygomatic arch and attaches to the processus coronoideus of the lower jaw.

3.M. pterygoideus lateralis, lateral pterygoid muscle, starts from the lower surface of the large wing of the sphenoid bone and from the pterygoid process and attaches to the neck of the condylar process of the lower jaw, as well as to the capsule and to the discus articularis of the temporomandibular joint.

4. M. pterygoideus medidlis, medial pterygoid muscle, originates in fossa pterygoidea pterygoid process and is attached on the medial surface of the mandibular angle symmetrically to m. masseter, to the tuberosity of the same name.

Function. M. masseter, m. temporalis and m. pterygoideus medialis, with an open mouth, pull the lower jaw to the upper, in other words, close the mouth. With the simultaneous reduction of both mm. pterygoidei laterales, the lower jaw is pushed forward. The backward movement is produced by the rearmost fibers of m. temporalis, running almost horizontally from back to front. If m. pterygoideus lateralis contracts only on one side, then the lower jaw is displaced sideways, to the side opposite to the contracting muscle. M. temporalis has a relation "to articulate speech, giving in the process a certain setting of the lower jaw.



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