![Temporal bone (sheep)](https://upload.wikimedia.org/wikipedia/commons/e/ec/Temporal_bone_%28sheep%29.jpg)
In
anatomy
Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...
, the temporomandibular joints (TMJ) are the two
joint
A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw ...
s connecting the jawbone to the
skull
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...
. It is a bilateral
synovial articulation between the
temporal bone
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex.
The temporal bones are overlaid by the sides of the head known as the temples, and house the structures of the ears. Th ...
of the skull above and the
mandible
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...
below; it is from these bones that its name is derived. This joint is unique in that it is a bilateral joint that functions as one unit. Since the TMJ is connected to the mandible, the right and left joints must function together and therefore are not independent of each other.
Structure
The main components are the joint capsule, articular disc, mandibular condyles, articular surface of the temporal bone, temporomandibular ligament, stylomandibular ligament, sphenomandibular ligament, and
lateral pterygoid muscle
The lateral pterygoid muscle (or external pterygoid muscle) is a muscle of mastication. It has two heads. It lies superior to the medial pterygoid muscle. It is supplied by pterygoid branches of the maxillary artery, and the lateral pterygoid ner ...
.
Capsule
The articular capsule (capsular ligament) is a thin, loose envelope, attached above to the circumference of the
mandibular fossa
The mandibular fossa, also known as the glenoid fossa in some dental literature, is the depression in the temporal bone that articulates with the mandible.
Structure
In the temporal bone, the mandibular fossa is bounded anteriorly by the art ...
and the
articular tubercle
The articular tubercle (eminentia articularis) is a bony eminence on the temporal bone in the skull. It is a rounded eminence of the anterior root of the posterior end of the outer surface of the squama temporalis. This tubercle forms the front bou ...
immediately in front; below, to the neck of the
condyle of the mandible
The condyloid process or condylar process is the process on the human and other mammalian species' mandibles that ends in a condyle, the mandibular condyle. It is thicker than the coronoid process of the mandible and consists of two portions: the c ...
. Its loose attachment to the neck of the mandible allows for free movement.
Articular disc
The unique feature of the temporomandibular joint is the
articular disc
The articular disk (or disc) is a thin, oval plate of fibrocartilage present in several joints which separates synovial cavities. This separation of the cavity space allows for separate movements to occur in each space.
The presence of an articula ...
. The disc is composed of dense fibrocartilagenous tissue that is positioned between the head of the mandibular condyle and the mandibular fossa of the temporal bone. The temporomandibular joints are one of the few
synovial joints
A synovial joint, also known as diarthrosis, joins bones or cartilage with a fibrous joint capsule that is continuous with the periosteum of the joined bones, constitutes the outer boundary of a synovial cavity, and surrounds the bones' articulat ...
in the human body with an
articular disc
The articular disk (or disc) is a thin, oval plate of fibrocartilage present in several joints which separates synovial cavities. This separation of the cavity space allows for separate movements to occur in each space.
The presence of an articula ...
, another being the
sternoclavicular joint
The sternoclavicular joint or sternoclavicular articulation is a synovial saddle joint between the manubrium of the sternum, and the clavicle, as well as the first rib. The joint possesses a joint capsule, and an articular disk, and is reinfor ...
. The disc divides each joint into two compartments, the lower and upper compartments. These two compartments are synovial cavities, which consist of an upper and a lower synovial cavity. The synovial membrane lining the joint capsule produces the synovial fluid that fills these cavities.
The disc is biconcave in shape. The anterior portion of the disc serves as the insertion site for the superior head of the
lateral pterygoid. The posterior portion attaches to the temporal bone. Both upper and lower compartments do not communicate with each other unless the disc is damaged.
The central area of the disc is avascular and lacks innervation, thus getting its nutrients from the surrounding synovial fluid. In contrast, the posterior ligament and the surrounding capsules along have both blood vessels and nerves. Few cells are present, but fibroblasts and white blood cells are among these. The central area is also thinner but of denser consistency than the peripheral region, which is thicker but has a more cushioned consistency. The synovial fluid in the synovial cavities provides nutrition for the avascular central area of the disc. With age, the entire disc thins and may undergo the addition of cartilage in the central part, changes that may lead to impaired movement of the joint.
The synovial membrane covers the inner surface of the articular capsule in the TMJ, except for the surface of the articular disc and condylar cartilage.
The lower joint compartment formed by the mandible and the articular disc is involved in rotational movement—this is the initial movement of the jaw when the mouth opens. The upper joint compartment formed by the articular disc and the temporal bone is involved in translational movement—this is the secondary gliding motion of the jaw as it is opened widely.
In some cases of anterior disc displacement, the pain felt during movement of the mandible is due to the condyle compressing this area against the articular surface of the temporal bone.
Ligaments
There are three ligaments associated with the temporomandibular joints: one major and two minor ligaments. These ligaments are important in that they define the border movements, or in other words, the farthest extents of movements, of the mandible. Movements of the mandible made past the extents functionally allowed by the muscular attachments will result in painful stimuli, and thus, movements past these more limited borders are rarely achieved in normal function.
*The major ligament, the
temporomandibular ligament
The temporomandibular ligament, also known as the external lateral ligament, is a ligament that connects the lower articular tubercle of the zygomatic arch to the lateral and posterior border of the neck of the mandible. It prevents posterior disp ...
, is actually the thickened lateral portion of the capsule, and it has two parts: an outer oblique portion (OOP) and an inner horizontal portion (IHP). The base of this triangular ligament is attached to the zygomatic process of the temporal bone and the articular tubercle; its apex is fixed to the lateral side of the neck of the mandible. This ligament prevents excessive retraction or moving backward of the mandible, a situation that might lead to problems with the joint.
[Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, page 118.]
*The two minor ligaments, the stylomandibular and sphenomandibular ligaments are accessory and are not directly attached to any part of the joint.
** The
stylomandibular ligament
The stylomandibular ligament is the thickened posterior portion of the investing cervical fascia around the neck. It extends from near the apex of the styloid process of the temporal bone to the angle and posterior border of the angle of the man ...
separates the infratemporal region (anterior) from the
parotid
The parotid gland is a major salivary gland in many animals. In humans, the two parotid glands are present on either side of the mouth and in front of both ears. They are the largest of the salivary glands. Each parotid is wrapped around the ma ...
region (posterior), and runs from the
styloid process to the
angle of the mandible __NOTOC__
The angle of the mandible (gonial angle) is located at the posterior border at the junction of the lower border of the ramus of the mandible.
The angle of the mandible, which may be either inverted or everted, is marked by rough, obliq ...
; it separates the parotid and submandibular salivary glands. It also becomes taut when the mandible is protruded.
** The
sphenomandibular ligament
The sphenomandibular ligament (internal lateral ligament) is one of the three ligaments of the temporomandibular joint. It is situated medially to - and generally separate from - the articular capsule of the joint. Superiorly, it is attached to the ...
runs from the
spine of the sphenoid bone
The sphenoidal spine (Latin: "''spina angularis''") is a downwardly directed process at the apex of the great wings of the sphenoid bone that serves as the origin of the sphenomandibular ligament.
Additional images
File:Spine of sphenoid bone.p ...
to the
lingula of mandible
The lingula of the mandible is a prominent bony ridge on the medial side of the mandible. It is next to the mandibular foramen. It gives attachment to the sphenomandibular ligament.
Structure
The lingula of the mandible is a prominent bony rid ...
. The inferior alveolar nerve descends between the sphenomandibular ligament and the ramus of the mandible to gain access to the mandibular foramen. The sphenomandibular ligament, because of its attachment to the lingula, overlaps the opening of the foramen. It is a vestige of the embryonic lower jaw, Meckel cartilage. The ligament becomes accentuated and taut when the mandible is protruded.
Other ligaments, called "oto-mandibular ligaments", connect the
middle ear
The middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea (of the inner ear).
The mammalian middle ear contains three ossicles, which transfer the vibrations of the eardrum into waves in the ...
(
malleus
The malleus, or hammer, is a hammer-shaped small bone or ossicle of the middle ear. It connects with the incus, and is attached to the inner surface of the eardrum. The word is Latin for 'hammer' or 'mallet'. It transmits the sound vibrations fro ...
) with the temporomandibular joint:
*
discomallear (or disco-malleolar) ligament,
*
malleomandibular (or malleolar-mandibular) ligament.
Nerve supply
Sensory innervation of the temporomandibular joint is derived from the
auriculotemporal
The auriculotemporal nerve is a branch of the mandibular nerve (CN V3) that runs with the superficial temporal artery and vein, and provides sensory innervation to various regions on the side of the head.
Structure
Origin
The auriculotempo ...
and
masseteric branches of
V3 or mandibular branch of the
trigeminal nerve
In neuroanatomy, the trigeminal nerve ( lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chewin ...
. These are only sensory innervation. Recall that motor is to the muscles.
The specific mechanics of
proprioception
Proprioception ( ), also referred to as kinaesthesia (or kinesthesia), is the sense of self-movement, force, and body position. It is sometimes described as the "sixth sense".
Proprioception is mediated by proprioceptors, mechanosensory neurons ...
in the temporomandibular joint involve four receptors.
Ruffini ending
The Bulbous corpuscle or Ruffini ending or Ruffini corpuscle is a slowly adapting mechanoreceptor located in the cutaneous tissue between the dermal papillae and the hypodermis. It is named after Angelo Ruffini
Angelo Ruffini (Pretare of Arquata ...
s function as static
mechanoreceptor
A mechanoreceptor, also called mechanoceptor, is a sensory receptor that responds to mechanical pressure or distortion. Mechanoreceptors are innervated by sensory neurons that convert mechanical pressure into electrical signals that, in animals, ...
s which position the mandible.
Pacinian corpuscle
Pacinian corpuscle or lamellar corpuscle or Vater-Pacini corpuscle; is one of the four major types of mechanoreceptors (specialized nerve ending with adventitious tissue for mechanical sensation) found in mammalian skin. This type of mechanorece ...
s are dynamic mechanoreceptors that accelerate movement during reflexes.
Golgi tendon organ
The Golgi tendon organ (GTO) (also called Golgi organ, tendon organ, neurotendinous organ or neurotendinous spindle) is a proprioceptor – a type of sensory receptor that senses changes in muscle tension. It lies at the interface between a musc ...
s function as static mechanoreceptors for the protection of ligaments around the temporomandibular joint.
Free nerve ending
A free nerve ending (FNE) or bare nerve ending, is an unspecialized, afferent nerve fiber sending its signal to a sensory neuron. ''Afferent'' in this case means bringing information from the body's periphery toward the brain. They function as cu ...
s are the pain receptors for the protection of the temporomandibular joint itself.
Free nerve endings, many of which act as
nociceptor
A nociceptor ("pain receptor" from Latin ''nocere'' 'to harm or hurt') is a sensory neuron that responds to damaging or potentially damaging stimuli by sending "possible threat" signals to the spinal cord and the brain. The brain creates the sens ...
s, innervate the bones, ligaments, and muscles of the TMJ. The fibrocartilage that overlays the TMJ condyle is not innervated and is avascular in healthy TMJs. When bone tissue, ligaments, or muscles become inflamed or injured, sensory signals are relayed along small-diameter
primary afferent nerve fibers that form the trigeminal nerve.
Signals are directed through the trigeminal nerve and modulated by neuronal cell bodies in the
trigeminal ganglion
A trigeminal ganglion (or Gasserian ganglion, or semilunar ganglion, or Gasser's ganglion) is the sensory ganglion at the base of each of the two trigeminal nerves (CN V), occupying a cavity (Meckel's cave) in the dura mater, covering the trigemi ...
. Nociceptive signals are subsequently routed to the
spinal trigeminal nucleus
The spinal trigeminal nucleus is a nucleus in the medulla that receives information about deep/crude touch, pain, and temperature from the ipsilateral face. In addition to the trigeminal nerve (CN V), the facial (CN VII), glossopharyngeal (CN IX), ...
, which contains second-order sensory neurons. From the trigeminal nucleus, sensory signals are relayed to higher-order brain regions, including the
somatosensory cortex
In physiology, the somatosensory system is the network of neural structures in the brain and body that produce the perception of touch (haptic perception), as well as temperature (thermoception), body position (proprioception), and pain. It is ...
and
thalamus
The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...
.
Blood supply
Its arterial blood supply is provided by branches of the
external carotid artery
The external carotid artery is a major artery of the head and neck. It arises from the common carotid artery when it splits into the external and internal carotid artery. External carotid artery supplies blood to the face and neck.
Structure
T ...
, predominately the
superficial temporal branch. Other branches of the external carotid artery, namely the
deep auricular artery
The deep auricular artery often arises in common with the anterior tympanic artery.
It ascends in the substance of the parotid gland, behind the temporomandibular articulation, pierces the cartilaginous or bony wall of the external acoustic meatu ...
,
anterior tympanic artery
The anterior tympanic artery (glaserian artery) is a small artery in the head that supplies the middle ear.
It usually arises as a branch of the first part of the maxillary artery. It passes upward behind the temporomandibular articulation, enters ...
,
ascending pharyngeal artery
The ascending pharyngeal artery is an artery in the neck that supplies the pharynx, developing from the proximal part of the embryonic second aortic arch.
It is the smallest branch of the external carotid and is a long, slender vessel, deeply sea ...
, and
maxillary artery
The maxillary artery supplies deep structures of the face. It branches from the external carotid artery just deep to the neck of the mandible.
Structure
The maxillary artery, the larger of the two terminal branches of the external carotid artery ...
, may also contribute to the arterial blood supply of the joint.
Development
Formation of the temporomandibular joints occurs at around 12 weeks ''
in utero
''In Utero'' is the third and final studio album by American rock band Nirvana. It was released on September 21, 1993, by DGC Records. After breaking into the mainstream with their second album, ''Nevermind'' (1991), Nirvana hired Steve Albini t ...
'' when the joint spaces and the articular disc develop.
[Salentijn, L. ''Biology of Mineralized Tissues: Prenatal Skull Development'', ]Columbia University College of Dental Medicine
The Columbia University College of Dental Medicine, often abbreviated CDM, is one of the twenty graduate and professional schools of Columbia University. It is located at 630 West 168th Street in Manhattan, New York City. According to American D ...
post-graduate dental lecture series, 2007 At approximately 10 weeks the component of the fetus future joint becomes evident in the
mesenchyme
Mesenchyme () is a type of loosely organized animal embryonic connective tissue of undifferentiated cells that give rise to most tissues, such as skin, blood or bone. The interactions between mesenchyme and epithelium help to form nearly every o ...
between condylar cartilage of the mandible and the developing temporal bone. Two slits like joint cavities and intervening disk make their appearance in this region by 12 weeks. The mesenchyme around the joint begins to form the fibrous joint capsule. Very little is known about the significance of newly forming muscles in joint formation. The developing superior head of the lateral pterygoid muscle attaches to the anterior portion of the fetal disk. The disk also continues posteriorly through the petrotympanic fissure and attaches to the malleus of the middle ear.
A growth center is located in the head of each mandibular condyle before an individual reaches maturity. This growth center consists of hyaline cartilage underneath the periosteum on the articulating surface of the condyle. This is the last growth center of bone in the body and is multidirectional in its growth capacity, unlike a typical long bone. This area of cartilage within the bone grows in length by appositional growth as the individual grows to maturity. Over time, the cartilage is replaced by bone, using endochondral ossification. This mandibular growth center in the condyle allows the increased length of the mandible needed for the larger permanent teeth, as well as for the larger brain capacity of the adult. This growth of the mandible also influences the overall shape of the face and thus is charted and referred to during orthodontic therapy. When an individual reaches full maturity, the growth center of bone within the condyle has disappeared.
Function
![Temporomandibular joint](https://upload.wikimedia.org/wikipedia/commons/f/f7/Temporomandibular_joint.jpg)
Each temporomandibular joint is classed as a "ginglymoarthrodial" joint since it is both a
ginglymus
A hinge joint (ginglymus or ginglymoid) is a bone joint in which the articular surfaces are molded to each other in such a manner as to permit motion only in one plane. According to one classification system they are said to be uniaxial (having ...
(hinging joint) and an
arthrodial
A plane joint (arthrodial joint, gliding joint, plane articulation) is a synovial joint which, under physiological conditions, allows only gliding movement.
Plane joints permit sliding movements in the plane of articular surfaces. The opposed sur ...
(sliding) joint.
The condyle of the mandible articulates with the
temporal bone
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex.
The temporal bones are overlaid by the sides of the head known as the temples, and house the structures of the ears. Th ...
in the
mandibular fossa
The mandibular fossa, also known as the glenoid fossa in some dental literature, is the depression in the temporal bone that articulates with the mandible.
Structure
In the temporal bone, the mandibular fossa is bounded anteriorly by the art ...
. The mandibular fossa is a concave depression in the
squamous portion of the temporal bone.
These two bones are actually separated by an
articular disc
The articular disk (or disc) is a thin, oval plate of fibrocartilage present in several joints which separates synovial cavities. This separation of the cavity space allows for separate movements to occur in each space.
The presence of an articula ...
, which divides the joint into two distinct compartments. The inferior compartment allows for rotation of the condylar head around an instantaneous axis of rotation,
corresponding to the first 20mm or so of the opening of the mouth. After the mouth is open to this extent, the mouth can no longer open without the superior compartment of the temporomandibular joints becoming active.
At this point, if the mouth continues to open, not only are the condylar heads rotating within the lower compartment of the temporomandibular joints, but the entire apparatus (condylar head and articular disc) ''translates''. Although this had traditionally been explained as a forward and downward sliding motion, on the anterior concave surface of the mandibular fossa and the posterior convex surface of the articular eminence, this translation actually amounts to a rotation around another axis. This effectively produces an
evolute
In the differential geometry of curves, the evolute of a curve is the locus of all its centers of curvature. That is to say that when the center of curvature of each point on a curve is drawn, the resultant shape will be the evolute of that curv ...
which can be termed the resultant axis of mandibular rotation, which lies in the vicinity of the mandibular foramen, allowing for a low-tension environment for the vasculature and innervation of the mandible.
The necessity of translation to produce further opening past that which can be accomplished with a sole rotation of the condyle can be demonstrated by placing a resistant fist against the chin and trying to open the mouth more than 20 or so mm.
The resting position of the temporomandibular joint is not with the teeth biting together. Instead, the muscular balance and proprioceptive feedback allow a physiologic rest for the mandible, an interocclusal clearance, or freeway space, which is 2 to 4 mm between the teeth.
The temporomandibular joint is less stable when teeth are clenched together (
occlusion
Occlusion may refer to:
Health and fitness
* Occlusion (dentistry), the manner in which the upper and lower teeth come together when the mouth is closed
* Occlusion miliaria, a skin condition
* Occlusive dressing, an air- and water-tight trauma ...
).
Jaw movement
Normal full jaw opening is 40-50 millimeters as measured from the edge of lower front teeth to edge of upper front teeth.
When measuring the vertical range of motion, the measurement must be adjusted for the overbite. For example, if the measurement from the edge of the lower front teeth to the edge of the upper front teeth is 40 millimeters and the overbite is 3 millimeters, then the jaw opening is 43 millimeters.
During
jaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth and serv ...
movements, only the mandible moves.
Normal movements of the mandible during function, such as
mastication
Chewing or mastication is the process by which food is crushed and ground by teeth. It is the first step of digestion, and it increases the surface area of foods to allow a more efficient break down by enzymes. During the mastication process, th ...
, or chewing, are known as excursions. There are two lateral excursions (left and right) and the forward excursion, known as protrusion. The reversal of protrusion is retrusion.
When the mandible is moved into protrusion, the mandibular
incisors
Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wh ...
, or front teeth of the mandible, are moved so that they first come edge to edge with the maxillary (upper) incisors and then surpass them, producing a temporary underbite. This is accomplished by translation of the condyle down the articular eminence (in the upper portion of the joint) without any more than the slightest amount of rotation taking place (in the lower portion of the joint), other than that necessary to allow the mandibular incisors to come in front of the maxillary incisors without running into them. (This is all assuming an ideal
Class I or
Class II occlusion
Class or The Class may refer to:
Common uses not otherwise categorized
* Class (biology), a taxonomic rank
* Class (knowledge representation), a collection of individuals or objects
* Class (philosophy), an analytical concept used differentl ...
.)
During chewing, the mandible moves in a specific manner as delineated by the two temporomandibular joints. The side of the mandible that moves laterally is referred to as either the working or rotating side, while the other side is referred to as either the balancing or orbiting side. The latter terms, although a bit outdated, are actually more precise, as they define the sides by the movements of the respective condyles.
When the mandible is moved into a lateral excursion, the working side condyle (the condyle on the side of the mandible that moves outwards) only performs rotation (in the horizontal plane), while the balancing side condyle performs the translation. During actual functional chewing, when the teeth are not only moved side to side but also up and down when biting of the teeth is incorporated as well, rotation (in a vertical plane) also plays a part in both condyles.
The mandible is moved primarily by the four
muscles of mastication
There are four classical muscles of mastication. During mastication, three muscles of mastication (''musculi masticatorii'') are responsible for adduction of the jaw, and one (the lateral pterygoid) helps to abduct it. All four move the jaw late ...
: the
masseter
In human anatomy, the masseter is one of the muscles of mastication. Found only in mammals, it is particularly powerful in herbivores to facilitate chewing of plant matter. The most obvious muscle of mastication is the masseter muscle, since it ...
,
medial pterygoid,
lateral pterygoid and the
temporalis
In anatomy, the temporalis muscle, also known as the temporal muscle, is one of the muscles of mastication (chewing). It is a broad, fan-shaped convergent muscle on each side of the head that fills the temporal fossa, superior to the zygomatic a ...
. These four muscles, all innervated by
V3, or the mandibular division of the
trigeminal nerve
In neuroanatomy, the trigeminal nerve ( lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chewin ...
, work in different groups to move the mandible in different directions. Contraction of the lateral pterygoid acts to pull the disc and condyle forward within the glenoid fossa and down the articular eminence; thus, the action of this muscle serves to protrude the jaw, it with the assistance of gravity, and the digastricus muscle also opens the jaw. The other three muscles close the mouth; the masseter and the medial pterygoid by pulling up the angle of the mandible and the temporalis by pulling up on the
coronoid process of the mandible
In human anatomy, the mandible's coronoid process (from Greek ''korōnē'', denoting something hooked) is a thin, triangular eminence, which is flattened from side to side and varies in shape and size. Its anterior border is convex and is continuou ...
.
Clinical significance
Pain
Temporomandibular joint pain is generally due to one of four reasons.
*Myofascial pain dysfunction syndrome, primarily involving the muscles of mastication. This is the most common cause.
*Internal derangements, an abnormal relationship of the disc to any of the other components of the joint. Disc displacement is an example of internal derangement.
*
Osteoarthritis
Osteoarthritis (OA) is a type of degenerative joint disease that results from breakdown of joint cartilage and underlying bone which affects 1 in 7 adults in the United States. It is believed to be the fourth leading cause of disability in the w ...
of the temporomandibular joint, a degenerative joint disease of the articular surfaces.
*
Temporal arteritis
Temporal may refer to:
Entertainment
* Temporal (band), an Australian metal band
* ''Temporal'' (Radio Tarifa album), 1997
* ''Temporal'' (Love Spirals Downwards album), 2000
* ''Temporal'' (Isis album), 2012
* ''Temporal'' (video game), a 200 ...
, for which it is considered a reliable diagnostic criteria
Pain or dysfunction of the temporomandibular joint is referred to as
temporomandibular joint dysfunction
Temporomandibular joint dysfunction (TMD, TMJD) is an umbrella term covering pain and dysfunction of the muscles of mastication (the muscles that move the jaw) and the temporomandibular joints (the joints which connect the mandible to the skul ...
or temporomandibular joint ''disorder'' (TMD). This term is used to refer to a group of problems involving the temporomandibular joints and the muscles, tendons, ligaments, blood vessels, and other tissues associated with them.
Although rare, other
pathologic
''Pathologic'' ( rus, Мор. Утопия, Mor. Utopiya, ˈmor ʊˈtopʲɪjə, , More. Utopia – a pun on Thomas More's ''Utopia'' and the Russian word for "plague") is a 2005 role-playing and survival game developed by Russian studio Ice-Pick ...
conditions may also affect the function of temporomandibular joints, causing pain and swelling. These conditions include
chondrosarcoma
Chondrosarcoma is a bone sarcoma, a primary cancer composed of cells derived from transformed cells that produce cartilage. A chondrosarcoma is a member of a category of tumors of bone and soft tissue known as sarcomas. About 30% of bone sarcomas ...
,
osteosarcoma
An osteosarcoma (OS) or osteogenic sarcoma (OGS) (or simply bone cancer) is a cancerous tumor in a bone. Specifically, it is an aggressive malignant neoplasm that arises from primitive transformed cells of mesenchymal origin (and thus a sarcoma) a ...
,
giant cell tumor, and
aneurysmal bone cyst
Aneurysmal bone cyst (ABC) is a non-cancerous bone tumor composed of multiple varying sizes of spaces in a bone which are filled with blood. The term is a misnomer, as the lesion is neither an aneurysm nor a cyst. It generally presents with pai ...
.
Examination
The temporomandibular joints can be felt in front of or within the external acoustic meatus during movements of the mandible.
Auscultation
Auscultation (based on the Latin verb ''auscultare'' "to listen") is listening to the internal sounds of the body, usually using a stethoscope. Auscultation is performed for the purposes of examining the circulatory and respiratory systems (hea ...
of the joint can also be performed.
Disc displacement
The most common disorder of a temporomandibular joint is disc displacement. In essence, this is when the articular disc, attached anteriorly to the superior head of the lateral pterygoid muscle and posteriorly to the retrodiscal tissue, moves out from between the condyle and the fossa so that the mandible and temporal bone contact is made on something other than the articular disc. This, as explained above, is usually very painful, because, unlike these adjacent tissues, the central portion of the disc contains no sensory innervation.
In most instances of disorder, the disc is displaced anteriorly upon translation, or the anterior and inferior sliding motion of the condyle forward within the fossa and down the articular eminence. On opening, a "pop" or "click" can sometimes be heard and usually felt also, indicating the condyle is moving back onto the disk, known as "reducing the joint" (''disc displacement with reduction''). Upon closing, the condyle will slide off the back of the disc, hence another "click" or "pop" at which point the condyle is posterior to the disc. Upon clenching, the condyle compresses the bilaminar area, and the nerves, arteries, and veins against the temporal fossa, causing pain and inflammation.
In disc displacement without reduction the disc stays anterior to the condylar head upon opening. Mouth opening is limited and there is no "pop" or "click" sound on opening.
Congenital disorders
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Aplasia
Aplasia (; from Greek ''a'', "not", "no" + ''plasis'', "formation") is a birth defect where an organ or tissue is wholly or largely absent. It is caused by a defect in a developmental process.
Aplastic anemia is the failure of the body to produ ...
of mandible or cranial bone
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Hypoplasia
Hypoplasia (from Ancient Greek ὑπo- ''hypo-'' 'under' + πλάσις ''plasis'' 'formation'; adjective form ''hypoplastic'') is underdevelopment or incomplete development of a tissue or organ.Hyperplasia
Hyperplasia (from ancient Greek ὑπέρ ''huper'' 'over' + πλάσις ''plasis'' 'formation'), or hypergenesis, is an enlargement of an organ or tissue caused by an increase in the amount of organic tissue that results from cell proliferati ...
of mandible or cranial bone
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Dysplasia
Dysplasia is any of various types of abnormal growth or development of cells (microscopic scale) or organs (macroscopic scale), and the abnormal histology or anatomical structure(s) resulting from such growth. Dysplasias on a mainly microscopic ...
abnormal tissue development
Traumatic disorders
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Mandibular dislocation
* Fracture
* Subluxation
Inflammatory disorders
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Synovitis
Synovitis is the medical term for inflammation of the synovial membrane. This membrane lines joints that possess cavities, known as synovial joints. The condition is usually painful, particularly when the joint is moved. The joint usually swell ...
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Capsulitis
In anatomy, capsulitis is inflammation of a capsule.
Types include:
* Adhesive capsulitis of shoulder
* Plica syndrome, which is an inflammation of the articular capsule of the knee joint
Adhesive capsulitis of shoulder
Adhesive capsulitis of ...
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Myositis
Myositis is a rare disease that involves inflammation of the muscles. This can present with a variety of symptoms such as skin involvement (i.e., rashes), muscle weakness, and other organ involvement. Systemic symptoms such as weight loss, fatigue ...
Degenerative disorders
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Osteoarthritis
Osteoarthritis (OA) is a type of degenerative joint disease that results from breakdown of joint cartilage and underlying bone which affects 1 in 7 adults in the United States. It is believed to be the fourth leading cause of disability in the w ...
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Rheumatoid arthritis
Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are involv ...
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Juvenile idiopathic arthritis
Juvenile idiopathic arthritis (JIA) is the most common, chronic rheumatic disease of childhood, affecting approximately one per 1,000 children. ''Juvenile'', in this context, refers to disease onset before 16 years of age, while ''idiopathic'' r ...
Idiopathic disorders
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Temporomandibular disorder
Temporomandibular joint dysfunction (TMD, TMJD) is an umbrella term covering pain and dysfunction of the muscles of mastication (the muscles that move the jaw) and the temporomandibular joints (the joints which connect the mandible to the skull ...
(TMD, also termed "temporomandibular joint pain-dysfunction syndrome") is pain and dysfunction of the TMJ and the
muscles of mastication
There are four classical muscles of mastication. During mastication, three muscles of mastication (''musculi masticatorii'') are responsible for adduction of the jaw, and one (the lateral pterygoid) helps to abduct it. All four move the jaw late ...
(the muscles that move the jaw). TMD does not fit neatly into any one etiologic category since the pathophysiology is poorly understood and it represents a range of distinct disorders with multifactorial etiology. TMD accounts for the majority of pathology of the TMJ, and it is the second most frequent cause of
orofacial pain
Orofacial pain is a general term covering any pain which is felt in the mouth, jaws and the face. Orofacial pain is a common symptom, and there are many causes.
Orofacial Pain (OFP) is the specialty of dentistry that encompasses the diagnosis, ma ...
after dental pain (i.e.
toothache
Toothache, also known as dental pain,Segen JC. (2002). ''McGraw-Hill Concise Dictionary of Modern Medicine''. The McGraw-Hill Companies. is pain in the teeth or their supporting structures, caused by dental diseases or pain referred to the te ...
).
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Fibromyalgia
Fibromyalgia (FM) is a medical condition defined by the presence of chronic widespread pain, fatigue, waking unrefreshed, cognitive symptoms, lower abdominal pain or cramps, and depression. Other symptoms include insomnia and a general hyp ...
References
External links
The American Association of Oral and Maxillofacial Surgeons (AAOMS) - The Temporomandibular Joint (TMJ)National Institute of Dental and Craniofacial Research, National Institutes of HealthInternational College of Cranio Mandibular Orthopedics
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Dental anatomy
Human head and neck
Joints
Joints of the head and neck
Skull
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