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- Creating an effective e-mail newsletter
- An article for everyone
- Using this template
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Sensory Innervation of the TM joint is derived from the auriculotemporal and masseteric branches of (number 5 cranial/skull nerve) trigeminal nerve and mandibular branch of trigeminal nerve supplies to the muscles. The TM joint involves receptors that function as (at rest location receptors) static mechanoreceptors to position mandible, to accelerate movement during reflexes, to protect the ligaments around Temporomandibular joint and the joint itself.
Its arterial blood (fresh blood) supply is provided by branches of the external carotid artery, predominately the superficial temporal branch. Other branches of the external carotid artery namely: the deep auricular artery, anterior tympanic artery, ascending pharyngeal artery and maxillary artery may also supply.
Author Dr Sharda Arora, CEO, Zental is an eminent TMJ Dentist and aesthetics.
TMJ Treatment In delhi
The Joint everyone needs to know about
The most important functions of the Temporomandibular joint (TMJ) are mastication (chewing) and speech; and it’s of great importance as many vital (living) structures are present nearby. TMJ is a complex joint allowing motion in only backward and forward direction in one plane and permits a gliding motion of the surfaces(ginglymoarthrodial joint, a term derived from ginglymus meaning a hinge joint and arthrodia meaning a gliding joint).The right and left TMJ form an ellipsoidal variety of the synovial joints similar to knee articulation(bicondylar articulation). It’s a different joint in its form and function than the other joints of the human body. Two joints are present on the each side of the face. Each joint is a double joint consisting of hallow joint cavities separated by a disc (articular disc) and each of them performs different functions. TMJ is a suspended joint between the two joint cavities; so it is also referred to as Floating Joint (Atypical Joint). Movement of one joint is dependent on movement of other joint. Therefore mandible is the only bone of the human body that has two joints which must work together. Hollow joint space has a fluid in between that helps in lubrication and prevents from friction (synovial fluid). It’s named ball and socket joint too as the anatomy consists of a ball shaped bone/ head (Condyle) and socket type bone (glenoid fossa) located in the temporal (temple) region of the skull bone
An article for everyone- The structure of this joint.
The disc (meniscus), remains between the ball shaped bone (Condyle) and socket type bone (glenoid fossa) and acts as a shock absorber. The disc has an indentation on the bottom side to accommodate the head of the ball shaped bone (Condyle). It is composed of larger structures on either side and behind it (cartilaginous disc and fibrous ligaments). The ligaments behind the disc (meniscus) functions as shock absorber when the lower jaw is drawn back as far as it will go. These ligaments are all connected to the ball shaped bone (Condyle) only at their periphery so that there is a thin “potential” space filled with non-frictional fluid (synovial fluid) both above and below the disc.
A potential space is a collapsed space like the one between a rubber glove and a hand. It is present, but not immediately apparent, and it could potentially get wider if air or water were introduced under the glove. The majority of physical derangements of the TM Joints involve damage to the disc or displacements of fragments of the disc.
A capsular covering is there for the TM joint. Think of it as a bag that contains the joint. It isolates the contents of the joint and allows free movement of the head of ball shaped bone (Condyle) and disc (articular disk) within a small “swimming pool” of non-frictional fluid (synovial fluid).The capsule has lots of blood vessels and nerves as well as connective tissue. Inflammation of the capsule (capsulitis) is a factor in much of the pain from TMJ disorders. All major joints in the body are surrounded by capsule (synovial capsule).
The structure of this template
As a person opens his mouth, the lower jaw swings at the TM Joint which is located just in front of the ear (tragus). By placing middle fingers lightly on this spot one can feel the Condyle, as it moves within the joint space. As one begins to open mouth, at first one can feel no movement of the joint. During this early part of jaw opening, the Condyle is simply rotating within the socket type bone (glenoid fossa). But during continual wider mouth opening, one can begin to feel the head of the Condyle moving forward (translation) and it is a normal part of opening the jaw wide. At this time the head of ball shaped bone (Condyle) slips forward and downward as it slides over the prominent part of the disc (articular eminence).
Different muscles are required for the opposite movements of the mandible (lower jaw). The muscles that help in chewing (muscles of mastication) are: jaw openers (abductors) and jaw closers (adductors). The muscle in temple region (temporalis), muscle on cheek (masseter), and one of the internal muscle that can’t be seen (medial pterygoids) are jaw closing muscles, while the outer muscle on the inside of jaw that can’t be seen (lateral pterygoids)is the primary muscle for jaw opening. Muscles that produce forward movement (protrusive) are also used alternately to move the jaw from side to side (laterally).
There are three external (extra capsular) ligaments. They act to stabilize the TMJ, preventing joint injury.
- Ligament that runs from the beginning of the discal tissue to the mandibular neck. It acts to prevent posterior dislocation of the joint (Lateral ligament)
- Another ligament originates from the spinal extension from skull (sphenoid spine) and attaches to the mandible (Sphenomandibular ligament).
- The third ligament runs along with the facial muscles and supports the weight of the jaw(Stylomandibular ligament).
Movements of the TMJ Joint
Movements at this joint are produced by the muscles of mastication, and the muscles attached below the angle of mandible (hyoid muscles). The two divisions of the Temporomandibular joint have different functions.
The upper part of the joint allows forward and backward movement (protrusion and retraction) of the mandible. The lateralpterygoid muscle is responsible for forward movement (protrusion), muscle attached to lower jaw (geniohyoid) and digastric muscles perform backward movement (retraction).
Opening and closing (depression and elevation) the mouth is permitted by the lower part of the joint. Opening movement (depression) is mostly caused by gravity. However, if there is resistance to opening, for example by hand, the digastric, muscle attached to lower jaw (geniohyoid) and mylohyoid muscles assist. Closing of the mouth (elevation) is very strong movement, caused by the contraction of the muscle of temple (temporalis), muscle of cheek (masseter) and internal muscle that can’t be seen (medial pterygoids muscles).