Examination of TMJ and muscles of mastication

2. •CONTENTS
•Introduction
•Anatomy of the joint
•Ligaments of the joint
•Articular disc
•Retro discal tissue
•Examination of the joint
•History taking
•Inspection
• palpation
•Examination of the muscles
•Conclusion
•References

3. DEFINITION
The temporomandibular joint (TMJ) is the articulation of the
mandibular condyle with the glenoid fossa of the temporal bone.
Normal movement of the mandible depends on proper function of the
TMJ. Externally, the preauricular area lies directly over the joint.

4. The TMJ is a ginglymoarthrodial joint, a term that is derived
from “ginglymus” meaning a hinge joint, allowing motion
only backward and forward in one plane, and “arthrodia”
meaning a joint of which permits a gliding motion of the
surfaces .
The right and left TMJ form a bicondylar articulation
and ellipsoid variety of the synovial joints similar to knee
articulation.

5. ANATOMY OF THE JOINT

6. BONY COMPONENTS OF THE JOINT
MANDIBLE
•It is a “U” shaped bone that supports the lower teeth and makes
up the lower facial skelton.
•It has no bony attachment to the skull.
•The condyle is the part of mandible that articulates with the
cranium , around which movements occur.
•From the anterior view , it has two projections
medial pole : more prominent
lateral pole : comparatively less prominent
•Mediolateral length : 15-20 mm
•Anteroposterior width : 8 -10 mm

7. TEMPORAL BONE
•The condyle articulates at the base of the cranium with the
squamous portion of the temporal bone.
•This portion of the bone is made up of , a concave mandibular fossa
, in which condyle is situated and is called articular or glenoid fossa.
•There is a convex bony prominence called the articular eminence.
•The degree of convexity of the articular eminence is highly variable
and is important because the steepness of the steepness of this
surface dictates the pathway of the condyle when the mandible is
positioned anteriorly.

8. THE ARTICULAR DISK (DISCUS ARTICULARIS;
INTERARTICULAR FIBROCARTILAGE; ARTICULAR MENISCUS)
The articular disk is a thin, oval plate, placed between the condyle of the mandible
and the mandibular fossa.
Made up of dense collagen,cartilage-like proteoglycans , elastic fibers.
Arrangement of collagen fibers:
at centre: perpendicular to transverse axis
periphery: interlaced and many fibers orient parallel to mediolateral aspect of
disc.

9. Cartilage – like proteoglycans contribute to compressive stiffness of the articular
cartilage.
Disc is attached by ligaments to medial and lateral poles of the condyle.these
ligaments permits rotational movement of the disc on the condyle during mouth
opening and closing.
Disc is thinnest at the centre and thickens to form anterior and posterior band
,this arrangement stablizes condyle in the glenoid fossa.
In between the anterior and posterior band is the intermediate zone which is the
thinnest.
In the normal joint the articulating
surface is located on intermediate zone
of the disc.

10. The disc and its attachment divides the joint into upper and lower compartments
that normally donot communicate.
Passive volume of upper compartment : 1.2 ml
lower compartment : 0.9 ml
MEDIAL VIEW OF MANDIBLE:
1.Articular eminence and upper joint
space
2.Anterior end of lower joint space
3.Lateral pterygoid muscle
4.Articular disc
5.Posterior end of upper joint space
6.Posterior end of lower joint space

11. SUPERIOR COMPARTMENT :
roof : mandibular fossa
floor : superior surface of the disc
INFERIOR COMPARTMENT :
roof : inferior surface of the disc
floor : articulating surface of the mandibular condyle
At its margin the disc blends with the fibrous capsule
Fibers of posterior one third of temporalis muscle and deep masseter muscle
attaches on anterolateral aspect
The Synovial Membranes.—The synovial membranes, two in number, are
placed one above, and the other below, the articular disk. The upper one, the
larger and looser of the two, is continued from the margin of the cartilage
covering the mandibular fossa and articular tubercle on to the upper surface of
the disk. The lower one passes from the under surface of the disk to the neck of
the condyle, being prolonged a little farther downward behind than in front. The
articular disk is sometimes perforated in its center, and the two cavities then
communicate with each other.

12. RETRODISCAL TISSUE:
A mass of soft tissue occupies the space behind the disc and condyle , also reffered
to as posterior attachment.
It is loosely organised system of collagen fibres,branching elastic fibres , fat , blood
and lymph vessels and nerves.
Unlike the disc itself, the retrodiscal tissue is vascular and highly innervated. As a
result, the retrodiscal tissue is often a major contributor to the pain o f
Temporomandibular Disorder (TMD), particularly when there is inflammation or
compression within the joint.
POSTERIOR
ATTACHMENT

13. LIGAMENTS OF TMJ:
1.TRUE LIGAMENT::
Fibrous capsule of the joint
Temperomandibular ligament
2.ACCESSORY LIGAMENT::
Sphenomandibular ligament
Stylomandibular ligament

14. LIGAMENTS OF THE JOINT
A ligament is a structure that connects two bones .
As with any joint system , ligaments play an important role in
protecting the structures.
Ligaments of the joint are made up of collagenous connective tissue
that have particular length and they do not stretch . However , if
extensive forces are applied to the ligament, whether suddenly or
over a prolonged period of time , the ligament can be elongated.
When this happens , it compromises the function of the ligament
, thereby altering joint function.
Ligaments do not enter the joint function actively , rather , they act
as passive restraining devices to limit and restrain border movements.

15. 1.TRUE LIGAMENT::
Collateral ligament
Fibrous capsule of the joint
Temperomandibular ligament
2.ACCESSORY LIGAMENT::
Sphenomandibular ligament
Stylomandibular ligament

16. COLLATERAL (DISCAL LIGAMENT)
•the collateral ligament attach the medial and lateral border of the articular
disc to the poles of the condyle.
•They are commanly called discal ligament and are two:
•
medial discal ligament
•
lateral discal ligament
•Medial discal ligament attaches to the medial edge of the disc to the medial
pole of the condyle
•Lateral discal ligament attaches lateral edge of the disc to lateral pole of
the condyle
•There function is to restrict movement of the disc away from the condyle.
In other words , they allow disc to move passively with the condyle as it
glides anteriorly and posteriorly.
The attachment of the discal ligament permits the disc to
Be rotated anteriorly and posteriorly on the articulating surface of the
condyle.
Thus the ligament are responsible for the hinging movement of TMJ which
occurs between condyle and articular disc

17. THE TEMPEROMANDIBULAR LIGAMENT
(LIGAMENTUMTEMPOROMANDIBULARE , EXTERNAL LATERAL LIGAMENT)
The temperomandibular ligament consists of two short, narrow fasciculi, one in
front of the other, attached
above to:
the lateral surface of the zygomatic arch and to the tubercle on its lower border.
below :
to the lateral surface and posterior border of the neck of the mandible.
It is broader above than below, and its fibers are directed obliquely downward and
backward.

18. •The oblique portion of the TM ligament resists excessive dropping
of the condyle therefore limiting the extent of mouth opening.
•This portion of the ligament also influences the normal opening
movement of the mandible
•During the normal phse of opening , condyle can rotate around a
fix point until the TM ligament becomes tight as its point of
insertion on the neck of the condyle is rotated posteriorly.
•When the ligament is taut the neck of condyle cannot move
further
•If the mouth were to open wider , the condyle would need to
move downward and forward across the articular eminence.

19. As the mouth opens,the teeth can be seperated about 20-25 mm , (A to B) without the
condyles moving from the fossae
As the mouth opens wide (B to C) the condyle moves downward and forward out of the
fossae.

20. •This effect can be demonstrated clinically by closing the
patient’s mouth and applying mild posterior force to the chin.
•With this force applied the patient shoukd be asked to open
the mouth.
•The jaw will easily rotate open until the teeth are 20-25mm
apart.
•At this point , resistance will be felt when the jaw is opened
wider.
•If the jaw is opened still wider, a distinct change in the
opening movement will be felt , which represents change from
rotation of the condyle around a fixed point to forward and
down the articular eminence.
•This change in movement is brought about by tightening of TM
ligament.in the erect postural position and with vertically
placed vertebral column , continued rotational movement of
the mandible would cause impingement of vital sub mandibular
and retromandibular structures of neck

21. •The inner horizontal portion of the TM ligament limits the
posterior movement of the condyle and the disc.
•When force is a[pplied to the mandible it displases the condyle
posteriorly , this portion of the ligament becomes tight and
prevents the movement of the condyle into posterior region of the
mandibular fossa.
•Therefore it prevents retrodiscal tissue from getting
traumatized.
•The inner horizontal portion also protects lateral pterygoid
muscle over-lenghtening or extension
•The effectiveness of this ligament is demonstrated during case
of extreme trauma to the mandible.
•In such cases neck of the condyle will fracture before retrodiscal
tissue are injured or before the condyle enters the midcranial
fossa.

22. FIBROUS CAPSULE OF THE JOINT:
•It is a thin inelastic fibrous connective tissue envelope that attaches to the
margins of the articular surfaces.
•It is attached superiorly to whole circumference of mandibular fossa
inferiorly to neck of mandible
•It stablizes the joint.
•It acts to resist any medial , lateral or
inferior forces that tend to dislocate
the articular surfaces.
•The capsular ligament is well
innervated and provide proprioceptive
feedback regarding position and
movement of the joint.

23. •The capsule is lined by synovium and joint cavity is filled with
synovial fluid.
•The synovial membrane consists of macrophage type A cells and
fibroblast like type B cells , like any other joint.
•Synovial fluid is a filtrate of plasma with added mucins and
proteins.
•Main constituent is hyaluronic acid.
•It lubricates the joint and decreses friction during joint compression
and motion.
•Joint lubrication occurs in two ways:
Weeping lubrication
Boundary lubrication

24. WEEPING LUBRICATION : it occurs as fluid is forced laterally during
compression and expressed through the unloaded fibrocartilage.
As the adjacent areas become loaded , weeping lubrication aids in
reducing friction.
BOUNDARY LUBRICATION : It is a function of water that is
physically bound to the cartiliginious surface by a glycoprotein.
DISTINGUISHING FEATURE OF THE JOINT
Covered by fibrocartilage rather than a hyaline cartilage.
Fibrocartilage is less distensible than hyaline cartilage due to a
greater number of collagen fibres.
The temporomandibular articulation is unique in the body
in that the two joints must always move simultaneously

25. ACCESSORY LIGAMENTS:
The Sphenomandibular Ligament (ligamentum sphenomandibulare; internal
lateral ligament The sphenomandibular ligament is attached
superiorly to : spine of sphenoid bone
inferiorly to : lingula of mandibular foramen
It is pierced by : mylohoid nerves and vessels
Morphologically , it is remnant of cephalic end of Meckel’s Cartilage (from which
mandible develops).
It does not have any significant limiting effects on mandibular movement.

26. STYLOMANDIBULAR LIGAMENT:
It is situated on posterior surface of TMJ.
Runs from the styloid process to the angle of the mandible.
It seperates parotid gland from submandibular salivary gland
Morphologically , it is thicken part of investing layer of deep cervical fascia.
It is thought to become tense during protrusive movement of the mandible and may
contribute to limiting protrusive movement.

27. THE OTO-MANDIBULAR LIGAMENTS are the discomalleolar
ligament (DML), which arises from the malleus and runs to the medial retrodiscal
tissue of the TMJ, and the anterior malleolar ligament (AML), which arises from
the malleus and connects with the lingula of the mandible via the
sphenomandibular ligament
The oto-mandibular ligaments may be implicated in tinnitus associated with TMD.
A positive correlation has been found between tinnitus and ipsilateral TMJ
disorder. It has been proposed that a TMJ disorder may stretch the DML and
AML, thereby affecting middle ear structure equilibrium
“It thus seems that otic symptoms
(tinnitus, otalgia (ear pain), dizziness
and hypoacusis) corresponding
to altered ossicular spatial
relationships can also be
produced from masticatory system
pathologies.”

28. BLOOD SUPPLY OF TMJ
TMJ is richly supplied by variety of vessels
that surrounds it.
Predominant is superficial temporal artery
branch of maxillary artery
Condyle recieves its vascular supply
through its marrow spaces by way of
inferior alveolar artery and by way of
“feeder vessels” that enter directly into
the condyle head both anteriorly and
posteriorly

29. NERVE SUPPLY OF TMJ:
Sensory innervation of the temporomandibular
joint is derived from
the auriculotemporal and masseteric branches
of V3 or mandibular branch of the trigeminal
nerve).

30. CLINICAL EXAMINATION OF TMJ
1. History taking
2. Measuring maximum interincisal opening
3. Palpation of pretragus area ; the lateral aspect of TMJ
4. Intra – auricular palpation ; the posterior aspect of TMJ
5. palpation of masseter muscle
6. Palpation of lateral pterygoid muscle
7. Palpation of medial pterygoid
8. Palpation of temporalis
9. Palpation of sternocliedomastoid
10.Palpation of digastric

31. SCREENING HISTORY AND EXAMINATION
Because the prevlance of TMD is very high , every patient who
comes to dental office should be screened for these problems
The purpose of screening history is to identify patients with
subclinical signs and symptoms that the patients may not relate
but are commonly associated with functional disturbances of
masticatory system (headache , ear symptoms)
The screening history consists of several questions that will help
orient the clinician to any TMD.

32. QUESTIONS TO BE ASKED:
Do you have pain in the face,front of ear and the temple area?
Do you get headaches , earaches , neckache , or cheek pain?
When is the pain at its worst ?
Do you experience pain when using the jaw?
Do you experience pain in the teeth?
Do you experience joint noises when moving your jaw or chewing?
Does your jaw ever lock or get stuck?
Does your jaw motion feel restricted?
Have you had any jaw injury?
Have you had treatment for jaw symptoms?if so , what was the
effect?
Do you have any other muscle , bone , or joint problem such as
arthritis?

33. FEATURES TO BE INCLUDED IN A THOROUGH OROFACIAL PAIN
HISTORY:
1.CHIEF COMPLAINT:
A.LOCATION OF PAIN
B.ONSET OF PAIN
CHIEF COMPLAINT:
This should be first taken in patient’s own language and then restated in
technical language.
If the patient has more than one pain complaints , each complaint should be
noted ans when possible , placed in a list according to significance to the
patient.

34. LOCATION OF THE PAIN:
•Patient’s ability to locate the pain with accuracy has diagnostic value
•The patient’s description of location of pain identifiesonly the site of
the pain.it is the examiner’s responsibility to determine whether it is
true source of the pain.
•If the pain is primary pain , source and site are in same location.
•If the pain is heterotropic , the patient will be directing attention to the
site of the pain.
•One key in locating the source of pain is local provocation that
accentuate it.
•When pain symptoms become complex , it is sometimes necessary to
use selective local anesthetic blockade of tissue to help differentiateb
the site from the source
•LA blockade of the source of pain will temporarily eliminate the
symptoms.
•Primary innervation of the joint is by auricular temporal nerve , with
secondary innervation from massetric and deep temporal nerves.

35. Auriculotemporal nerve can be blocked by inserting 27 gauge
needle through the skin , just anterior and slightly above the
junction of tragus and earlobe.
Needle is then advanced until it touches the posterior neck of the
condyle.
Once the neck of the condyle is felt , tip of the needle is carefully
moved slightly behind the posterior aspect of the condyle in
anteromedial direction to a depth of 1cm
The syringe is then aspired and if no blood is seen , the solution is
deposited.
If the true source of the pain is the joint , the pain should be
eliminated or decreased in approx 5min

36. ONSET OF THE PAIN:
It is important to assess any circumstances that were
associated with the initial onset of the pain complaint .
These circumstances may give an insight as to cause.
For example , in some instances the pain complaint began
immediately after a motor vehicle accident.
Trauma is frequent cause of pain condition and not only gives
insight as to cause but also enlightens the examiner to the other
considerations , such as other injury , related emotional
trauma.
The onset of some pain are associated with systemic illness
, jaw function , or may be spontaneous.

37. PHYSICAL EXAMINATION OF THE
JOINT

38. INSPECTION
Facial asymmetry, swelling , masseter or temporalis muscle
hypertrophy muscle
Assesment of range of mandibular movements:maximum mouth
opening , lateral movement , deviation white opening , protrusive
movement

39. •The maximum opening
distance between the incisal
edges of upper and lower
incisor is measured using scale ,
Boley gauge or ruler
•Normal opening – 40 to 55 mm
•Normal opening can also be
estimated by patient’s own finger
•Normal : three finger end on end
•Two finger opening reveals reduction
in opening but not necessarily
reduction in function
•One finger opening indicates reduced
function

40. Maximum mouth opening should be measured
without pain
as wide as possible , with pain
after opening with clinical assistance
Mouth opening with assistance is accomplished by applying mild to
moderate pressure against the upper and lower incisors with thumb
and index finger . passive stretching is a technique for assessing
limitation due to muscle or joint problem
Assisted opening can be compared with active opening (≥40 mm)
This procedure provides the examiner with the quality of resistance at
the end of the movement.

41. •Restricted mouth opening is considered to be any distance less than 40mm.
•This distance is measured by observing the incisal edge of the mandibular
central incisor travelling away from its position at maximum intercuspation.
•If a person has 5mm vertical overlap of anterior teeth and maximum
interincisal distance is 57mm , the mandible has actually moved 62mm in
opening.
•If mouth opening is restricted , it is helpful to test the “end feel”
•End feel describes the characteristics of restriction.
•End feel can be evaluated by placing the fingers between patient’s upper and
lower teeth and applying gentle-but-steady force in an attempt to passively
increase the interincisal distance.

42. muscle restriction are associated with soft end feel and results in
increase of >5mm above the active opening (wide opening with
pain)
joint disorders such as acute non reducing disc displacement
have hard end feel and characteristically limit assisted opening
to <5mm

43. LATERAL RANGE OF MOVEMENT
Normal lateral range of movement
is >7mm
Measurements are made with
teeth slightly seperated,measuring
the displacement of lower midline
from maxillary midline.
Any condition (tumor, muscle
spasm, fracture, ankylosis,
displaced meniscus) that prevents
the normal translation
of one condyle will not prevent the
contralateral condyle from
sliding forward normally . The
result is deviation of the chin
toward the affected side .

44. Examine the hands for signs of systemic disease (e .g.,
Heberden's nodes of osteoarthrosis, ulnar deviation of
rheumatoid arthritis), which may also involve the TMJ .
Laboratory tests (e .g., complete blood count, erythrocyte
sedimentation rate, rheumatoid factor, antinuclear antibody,serum
uric acid) are helpful when a systemic cause for TMJ disease is
suspected.

45. In patients with an intracapsular restriction (disc displacement without
restriction) a contralateral eccentric movement will be limited , but an
ipsilateral movement will be normal.
However with muscle disorders , the elevators (temporalis , masseter , medial
pterygoid) are responsible for limited mouth opening , because eccentric
movements donot generally lenghten these muscles , nor a normal range of
eccentric movement exists.

46. Observe the opening pattern for deviation . The
mandible often deviates
towards the affected side during opening
because of muscle spasm or mechanical locking
by a displaced meniscus

47. •When the mouth is opened the pathway of mandible is observed
for any deviations or deflections.
•If deviation occurs during opening and the jaw returns to the
midline before 30-35mm of total opening , it is likely to be
associated with a disc derrangement disorder.
•If the speed of opening alters the location of the deviation , it is
likely to be a discal movement (ex disc displacement with
reduction)
•If the speed of opening does not alter the interincisal distance of
deviation , and if the location of deviation is the same for opening
and closing , then a structural incompatibility is likely the
diagnosis.
•Muscle disorders that cause deviation of mandibular opening
pathways are commonly large , inconsistent , sweeping
movements are not associated with joint sounds.
•Deviation can also occur due to subluxation at wide open
position.

48. This is an intracapsular disorder , but not necessarily a pathologic
condition.
Deflection of the mandibular opening pathway results when one condye
doesnot translate.this may be caused by an intra capsular proberm ( disc
dislocation without reduction )
With these problems , mandible will deflect to the ipsilateral side during
late stages of opening.
Deflection can also result if a unilateral elevator muscle , such as
masseter becomes shortened (myospasm).
This condition can be seprated from intracapsular disorders by observing
the protrusive and lateral eccentric movements.
If the problem is intracapsular , mandible will move to the side of
involved joint during protrusion and be restricted during contralateral
movement (ie. Normal movement to the ipsilateral side)
If the problem is extracapsular , there will be no deflection during the
protrusive movement and no restriction in lateral movements.

49. When deflection is due to intracapsular source , mandible will
always move towards involved joint.
If deflection is due to shortened muscle the direction in which
mandible moves will depend on the position of the involved
muscle with respect to the joint.
If the muscle is lateral to the joint , (ie masseter or temporalis) ,
deflection will be towards the involved muscle.
If medial to the joint , (ie medial pterygoid) deflection will be
away from the involved muscle (in contralateral direction).

50. •MALOCCLUSION:
•Sometime acute malocclusion occurs.
•An acute malocclusion caused by a muscle disorder will vary
according to the muscle involved.
•If inferior lateral pterygoid is in spasm and shortens , condyle will
be brought slightly forward in the fossa on the involved side.this
will result in disocclusion of ipsilateral posterior teeth and heavy
contact on contralateral canines.
•If the spasms are in elevator muscles , the patient is likely to
report a feeling that “teeth suddenly don’t fit right”
•An acute malocclusion resulting from an antracapsular disorder is
usually very closely related to the event that changed the joint
function.
•If the disc is suddenly displaced , the thicker posterior band may
be superimposed between condyle and fossa and cause a sudden
increase in discal space.This appears clinically as loss of ipsilateral
posterior teeth contact.

51. If the disc becomes suddenly dislocated , collapse of discal space
can occur as the condyle compresses the retrodiscal tissue.
The patient notes it as sudden change in occlusion characterized
as heavy posterior teeth contact on ipsilateral side.
If this condition continues , retrodiscitis may result and cause
tissue inflammation with swelling of retrodiscal tissue.
The resulting malocclusion may now change to one characterized
by loss of posterior tooth contact on the ipsilateral side.

52. Palpation of pretragus area ; the lateral aspect of TMJ
Palpate directly over the joint
while the patient opens and
the mandible, and the extent of
mandibular condylar movement
can be assessed .
Normally, condylar
movement is easily felt . Have
the patient close slowly, and
you will feel the condyle move
posteriorly against your finger.

53. •opening :involves two motions. First, the mandibular condyle
rotates anteriorly on the disk. Second, the condyle and the disk
both glide anteriorly and inferiorly over the articular tubercle of the
temporal bone

54. Tenderness elicited by this maneuver is invariably associated with
articular inflammation
Also , there may be palpable differences in the form of the condyle
comparing right and left. A condyle that do not translate may not
be palpable during mouth opening and closing. This may be finding
associated with an anterior disc displacement without reduction
A click that occurs on opening and closing is eleminated by bringing
the mandible into a protrusive position before opening is most often
associated with anterior disc displacement with reduction.
PROVOCATION TEST:
it is designed to elicit the described pain.
Since pain is often aggravated by jaw use , a positive response adds
support for diagnosing TMD.
THE STATIC PAIN TEST involves having the mandible slightly open
and remainig in one position while the patient resists the slowly

55. Increasing manual force applied by the examiner in a lateral
, upward , and downward direction.
If the mandible remains in static position , muscles will be
subjected to activation
However ability of this test to discriminate between muscle and
joint pain is not known

56. JOINT SOUNDS
There are 2 types of joint sound to look out for:
Clicks - single explosive noise of short duration.
Crepitus - continious 'grating' noise
CLICKS
•A joint click probably represents the sudden distraction of 2 wet
surfaces, symptomatic of some kind of disc displacement. The diagnosis of a joint
click, and therefore treatment, varies on whether the click is :
left, right or bilateral,
painful or painless,
consistent or intermittent.
•The timing of a click is also significant: a click heard later in the opening cycle may
represent a greater degree of disc displacement.
•Clicks may frequently be felt as well as heard, though they are not normally
painful.
•Condylar hypermobility , enlargement of lateral pole of condyle,structural
irregularity of eminence.
•If the click is relatively loud , it is referred to as a “pop”

57. CREPITUS :
•Crepitus is the continuous noise during movement of the
joint, caused by the articulatory surfaces of the joint being worn. This
occurs most commonly in patients with degenerative joint disease.
•The joint sounds should be listened to with a stethoscope.

58. Auscultate TMJ noises (not routinely
done)

59. TMJ can also be palpated through anterior wall of external auditory
meatus

60. EXAMINATION OF THE MUSCLES
Functional disorders of the masticatory muscles are probably the
most common TMD complaint of the patients seeking treatment
in the dental office.
With regard to pain , they are second to odontalgia in terms of
frequency.
They are generally grouped in large category known as
“masticatory muscle disorder”
As with any pathologic state two major symptoms can be
observed:
1.Pain
2.dysfunction

61. PAIN
Certainly the most common complaint in patients with
masticatory muscle disorder is pain , which may range from
slight tenderness to extreme discomfort.
Pain felt in muscle tissue is called myalgia.
It may arise from increased level of muscle use.
Symptoms are usually associated with a feeling of muscle
fatigue and tightness.
Some authors suggest it is related to vasoconstriction of relevant
nutrient arteries and accumulation of metabolic w3aste products
in the muscle tissue.
Within the ischemic area of the muscle , certain algogenic
substances (eg bradykinin , prostaglandins) are released ,causing
muscle pain.

62. Severity of muscle pain is directly related to the extent of the
functional activity.
Therefore patients always report that pain affects their functional
activity.
The clinician must also remember that , myogenous pain is a type
of deep pain , and if it becomes constant, can produce central
excitatory effects.
Therefore it can reinitiate more muscle pain (ie cyclic effect)
This clinical phenomenon was first described in 1942 as “cyclic
muscle spasm” .
More recently , with the findings that the painful muscles are not
truly in spasm,the term “cyclic muscle pain” was coined.
Another very common symptom associated with masticatory
muscle pain is headache.

63. DYSFUNCTION
Usually it is seen as decrease in range of mandibular movement.
When muscle tissues have been compromised by overuse , any
contraction or stretching increases the pain.
Therefore to maintain comfort , patient restricts movement within
a range that doesnot increase the pain level.
Clinically this is seen as inability to open mouth widely.

64. TEMPORALIS MUSCLE
It is a large fan shaped
muscle that originates from
temporal fossa and lateral
surface of skull.
Its fibers comes downward
zygomatic arch and lateral
surface of the skull to form
a tendon that inserts into
coronoid process and
anterior border of
ascending ramus.

65. It can be divided into three distinct areas:
Anterior portion : consists of fibers that are direcrted vertically
Middle portion : contains fibers that run obliquely across lateral
aspect of the skull
Posterior portion : that are aligned almost horizontally
When temporal muscle contracts , it elevates mandible.

66. Anterior,
Middle and
Posterior
portions of the
temporalis muscle
should be palpated

67. Temporalis muscle can be seen and readily palpated throughout entire
length and breadth when the patient’s teeth are firmly clenched.

68. MASSETER MUSCLE
ORIGIN:
Superficial portion – anterior 2/3
of lower border of zygomatic
arch
Deep portion – medial surface of
Zygomatic arch
INSERTION:
Lateral surface of ramus,
Coronoid process, and angle of
mandible
FUNCTION:
Elevates mandible, clenches teeth

69. Palpate multiple areas of
the masseter muscle
As with temporalis muscle,it can be
located when patient’s jaw are
forcibly closed.the body of masseter
can be palpated with thumb and
index finger.index finger can palpate
the entire body of masseter.

70. MEDIAL PTERYGOID / INTERNAL PTERYGOID
ORIGIN:
Medial surface of lateral pterygoid plate
and tuberosity of maxilla and can not be
palpated
INSERTION:
lower medial surface of ramus of mandible
FUNCTION:
Elevation and protraction

71. Anterior part of insertion can be palpated by placing the finger at 45 degrees in
the floor if the patients mouth near base of the relaxed tongue.
The opposite hand can be used to extraorally to palpate posterior and inferior
portions of insertion.
Body of the muscle can be palpated by rotating the index finger upwards against
the muscle to near its origin on the tuberosity.

72. LATERAL / EXTERNAL PTERYGOID
ORIGIN:
It originates in two parts:
Superior head from the greater wing of
sphenoid
Inferior head the lateral surface of the
pterygoid plate
INSERTION:
Neck of condyle and articular disc of TMJ.
FUNCTION:
protraction

73. PALPATION OF LATERAL PTERYGOID MUSCLE
The muscle is palpated by using the little or index finger and placing it lateral to
maxillary tuberosity and medial to coronoid process.The finger presses upwards
and inwards and a painful response can be determined .

74. Demonstration of the lateral pterygoid’s attachme
anterior articular disc has led to the theory that some
anterior disc displacements may be related to its
dysfunction.
Hyperactivity of the muscle is capable of pullind the disc
forward from its normal position.

75. STERNOCLIEDOMASTOID MUSCLE
The sternocleidomastoid passes
obliquely across the side of the neck.
It is thick and narrow at its central
part, but broader and thinner at either
end.
medial or sternal head , which arises
from the upper part of the anterior
surface of the manubrium sterni , and
is directed superiorly, laterally, and
posteriorly.
lateral or clavicular head arises
from the superior border and anterior
surface of the medial third of
the clavicle ; it is directed almost
vertically upward.

76. DIGASTRIC
ORIGIN
anterior belly - digastric fossa (mandible)
posterior belly - mastoid process of temporal
bone
INSERTION: Intermediate tendon (hyoid bone)
ACTION:
When the digastric muscle contracts, it acts to
elevate the hyoid bone.
If the hyoid is being held in place), it will tend
to depress the mandible (open the mouth).

77. PALPATION OF THE MUSCLES
The SCM is effectively palpated on each side of the neck when the patient moves the
head to the contralateral side

78. REFERENCES

79. ReferencesB D Chaurasia.Human anatomy:Regional and applied dissection amd clinical,5th
edition
Drake L R, Vogl W, Mitchell A W M. Gray’s anatomy for student.InternationalEdition.
Sinnatamby C S. Last’s anatomy regional and applied. 11th edition.
Lippert, L.S. (2011). Clinical Kinesiology and Anatomy, 5th ed. Philadelphia, PA: F.A.
Davis.
Blaschke DD, Solberg WK, Sanders B . Arthrography of the temporomandibular
joint : review of current status . J Am Dent Assoc 1980 ; 100:388 .
Kahan LB . Temporomandibular joint dysfunction : an occasional manifestation of
serious psychopathology . J Oral Surg 1981 ; 39:742 .
Meyer RA. Osteochondroma of coronoid process of mandible . J Oral Surg 1972 ;30 :297
Meyer RA . Clicking sounds owing to temporomandibular joint injury.JAMA 1982 ;248