Temporomandibular Joint (TMJ) Anatomy (3D Anatomy Tutorial)

Temporomandibular Joint (TMJ) Anatomy (3D Anatomy Tutorial)

Hey, I’m James and today I’m going to discuss the temporomandibular joints I Will start by discussing the Associated bones and some important landmarks. I will then discuss the joints itself and then the muscles of mastication Finally, I’ll discuss jaw dislocation and how this is resolved Make sure to subscribe to be the first to know when we release new videos to understand the TMJ and the muscles of mastication We must first consider the bones and the associated bony landmarks. The bones to consider are the temporal bone the sphenoid bone the zygomatic bone the maxilla and The mandible So let’s start with the mandible the Mandible has two superior processes the condyloid process and the coronoid process And between we have the mandibular notch Moving in fairly we have the neck The ramus and the angle anteriorly the body is located here Just lateral to that of the mental foramina which we can see here and here The mental nerves exit here and provide sensory innervations to the chin and some of the mandibular teeth The mental nodes are branches of the inferior alveolar nerve and consequently the mandibular division of the trigeminal nerve The mandibular foramina and submandibular fossa are located on the internal aspect of the mandible The submandibular gland is pushed up against a fossa Whereas the inferior alveolar nerve enters into the mandibular canal here via the mandibular foramen So let’s now focus on the temporal bone The pointer wished the condyloid process of the mandible articulates with the temporal bone. Is that the mandibular fossa? When the jaw is low It is limited anteriorly by the articular tubercle here or Sometimes known as the articular eminence, which is a portion of the zygomatic arch Posteriorly we can see the external auditory meatus And posterior inferior to that of the mandibular fossa is the mastoid process Just for completeness, We can see the styloid process here So now we demand a bell back in with the model we can talk about the temporomandibular joint The TMJ is a synovial joints at the articulation between the condyloid process of the mandible and The mandibular fossa of the temporal bone in a region known as the infra temporal fossa the joint includes an articular disc that splits the TMJ into an upper compartment and A lower compartment and this is the articular disc here Gliding movements are permitted in the upper components such as protrusion and retraction as well as side to side movements In the lower compartments Rotational movements occur such as elevation and depression Depression of the jaw will only occur once a condyloid process has moved anteriorly within the upper compartments here The movement is limited anteriorly by the articular tubercle, which we can see on the model The TMJ will be dislocated if the condyloid process moved beyond the articular tubercle The TMJ is surrounded by joint capsule which we can see here and is further supported by some extra capsular ligaments The lateral temporomandibular ligaments, which we can see here attaches to the zygomatic arch And the posterior portion of the neck of the mandible this ligaments limits posterior movements of the mandible The medial ligaments include two sphenomandibular ligaments and stylomandibular ligaments both for which limits lateral movements Thus we know mandibular ligament runs from the ramus of the mandible to the sphenoid bone And the stylomandibular ligament runs from the ramus of the mandible to the styloid process Now I’ll move on to the muscles of mastication the pterygoid muscles are located medial to the mandible The medial pterygoid muscle has two heads: a deep head and a superficial heads The deep head is attached to the medial aspects of the lateral pterygoid plates, which is approximately here The superficial head attaches to the maxilla as well as the palatine bones Both heads run posterior inferiorly to reach a point to which they fuse approximately here This fused muscle will then insert onto the ramus of the mandible, which we can see here The lateral pterygoid is best seen on a lateral view of the model So to see the pterygoids we must first remove the ramus of the mandible here So now with the ramus removed we can see the superficial head of the medial pterygoid muscle Up here, We can see the lateral pterygoid muscles with a superior head and an inferior head here The superior head attaches to the roof of the infra temporal fossa as well as the lateral portion of the lateral pterygoid plates here the inferior head attaches to the lateral portion of the lateral pterygoid plates moving posteriorly Both heads will fuse and will attach to the condyloid process of the mandible located approximately here When the lateral pterygoid muscles out bilaterally they protrude the jaw This movement is paramount to our opening of the mouth Unilateral contraction swings our jaw to the contralateral side Bilateral action of the medial pterygoid muscles close the jaw and will also assist in protrusion Unilateral contraction will swing the jaw to the contralateral side The fan-shaped temporalis muscle arises from the temporal fossa located here and the fibers attach onto the coronoid process of the mandible located here The anterior fibers run vertically and will assist in closing the jaw The posterior horizontal fibers, which we can see here will retract to the mandible The masseter muscle is located on the lateral side of the mandible just here It has two heads a superficial head and a deep head the attachments are the zygomatic bone and the zygomatic arch, which we can see Both muscles slope inferiorly to then attached onto the ramus and angle of the mandible here This muscle elevates the mandible to close the mouth All of the muscles of mastication are innervated by the mandibular division of the trigeminal nerve The jaw is most stable when it is closed and a tee far in occlusion Anterior dislocation is the most common form of displacement Anterior dislocation is opposed by the articular tubercle the lateral ligament and a contraction of medial pterygoid masseter and temporalis However, in the instance of anterior dislocation the condyloid process moves anterior to the articular process and the muscles of mastication Spasm the combination of which prevents retraction of the mandible this spasm Must be overcome by putting downward pressure on inferior molars and then guiding the head or the mandible back into the mandibular fossa So just a quick summary the temporomandibular joint is a synovial joint formed by the articulation of the condyloid process of the mandible and the mandibular fossa of the temporal bone An articular disc sits within the joints which creates an upper and lower cavity The upper cavity allows for gliding movements, whereas the lower cavity allows for rotational movements the muscles of mastication acts on the joints The TMJ is most stable when the jaw is closed We’d love to hear your feedback on what you thought of this video and what topics you’d like us to cover in the future You can do this by leaving a comment or dropping us an email

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