LO 4 Flashcards
(46 cards)
1
Q
List the structures of the Temporomandibular Joint (TMJ)
A
- Temporal bone
- Mandible
- Joint capsule
- Disc of the joint
2
Q
Describe the temporomandibular joint (TMJ)
A
- The TMJ is the articulation of the temporal bone and the mandible on each side of the head
- Temporal bone is a cranial bone that articulates with the facial bone of the mandible at the TMJ by way of the joint disc.
- bilateral
- allows for movement of the mandible for mastication, speech, and respiratory movements
- the most unique and complex set of joints in the body – both joints must always move simultaneously
3
Q
What are the 2 distinct movements of the TMJ?
A
Rotation and translation - occur in the joint during mandibular opening and closing.
4
Q
Describe the sensory innervation of the TMJ
A
Auriculotemporal and masseteric branches of the mandibular nerve( or third division)of the fifth cranial nerve- trigeminal nerve
5
Q
What is the motor function of the TMJ?
A
Muscles of mastication
6
Q
Describe the blood supply of the TMJ
A
- Branches of external carotid artery:superficial temporal branch+ maxillary artery
- Veins - superficial temporal, maxillary and pterygoid
7
Q
Describe the articular eminence
A
- On the temporal bone, anterior to the articular fossa
- A smooth, rounded protuberance on the inferior aspect of the zygomatic process
8
Q
Describe the Articular Fossa (aka Glenoid Fossa / aka Mandibular Fossa)
A
- Posterior to the articular eminence
- A depression on the inferior aspect of the temporal bone
- Posterior and medial to the zygomatic arch
- Posterior to the articular fossa is a sharper ridge - the postglenoid process.
9
Q
The mandible articulates with each temporal bone at the articulating surface of the _________
A
head of the condyle
10
Q
Describe the joint capsule of the TMJ
A
- A joint capsule completely wraps around and encloses the TMJ
- Superior - articular eminence and articular fossa
- Inferiorly - condyle (at the level of the condyle’s neck)
11
Q
Describe the articular disc (meniscus)
A
- located on each side between the temporal bone and condyle
of the mandible - On sagittal section ,it appears like a cap on the mandibular condyle
- The joint disc divides the TMJ into two synovial cavities: upper & lower
- The synovial membranes inside the joint capsule secrete synovial fluid – clear, viscous fluid
- Posteriorly, 2 divisions - The upper division: is attched to the postglenoid process; The lower division: attaches to the neck of the condyle
12
Q
What is a ligament?
A
- A band of fibrous tissue that connects bones
- In the TMJ, it prevents excessive retraction of mandible
13
Q
What are the 3 paired ligaments of the TMJ
A
- Temporomandibular - major ligament; provides strength to the joint; prevents excessive retraction of mandible
- Stylomandibular - runs from styloid process of temporal bone to angle of mandible; becomes taut when mandible protrudes
- Sphenomandibular: not considered a part of TMJ; becomes taut when mandible protrudes; can prevent diffusion of local anesthetic agent during inferior alveolar nerve block.
14
Q
What are the muscles of mastication responsible for?
A
- opening the jaws (depression)
- closing the jaws (elevation)
- moving the mandible forward (protrusion) and backward (retraction)
- shifting the mandible to one side (lateral
excursion /deviation) - These jaw movements involve the movement of the mandible—the rest of the skull remains relatively stable.
- Muscles of mastication work with the TMJ to accomplish these movements of the mandible
15
Q
Describe the 2 basic movements of the mandible (performed by the TMJ and its associated muscles of mastication)
A
- Gliding (sliding)
- Rotational (hinge)
16
Q
Describe gliding (sliding)
A
- Occurs mainly between the disc and the articular eminence of the temporal bone in the upper synovial cavity
- The disc plus the condyle move forward or backward, and down and up the articular eminence.
- The gliding movement allows the mandible to move forward or backward.
- Bringing the mandible forward involves protrusion of the mandible.
- Bringing the mandible backward involves retraction (retrusion) of the mandible
17
Q
Describe rotational movement (hinge)
A
- Occurs mainly between the disc and the condyle in the lower synovial cavity
- The axis of rotation of the disc plus the mandibular condyle is transverse
- The movements accomplished are depression or elevation of the mandible
- Depression of the mandible lowers the jaw.
- Elevation of the mandible raises the jaw.
18
Q
With these two types of movements, gliding and rotation, and with the right and left TMJs working together, the finer movements of the jaw can be accomplished. These include ___________
A
opening and closing the jaws and shifting the mandible to one side
19
Q
Describe lateral excursion/deviation of the mandible
A
- involves shifting the lower jaw to one side
- involves both gliding and rotational movements of opposite TMJs in their respective joint cavities.
- During lateral deviation, one disc and the mandibular condyle glides
forward and medially on the articular eminence in the upper synovial
cavity, while the other condyle and disc remain relatively stable in position in the articular fossa. - These actions produce rotation around the more stable condyle.
- During mastication, the power stroke (when the teeth crunch the food) involves a movement from a laterally deviated position back to the midline.
- If the food is on the right side of the mouth, the mandible is deviated to the right.
- The power stroke returns the mandible to the centre, and thus the movement is to the left and involves retraction of the left side; the reverse situation occurs if the food is on the left.
20
Q
Describe the mechanics of opening and closing the jaw
A
- Opening the jaws, which occurs during mastication, speech, and respiratory movements, involves both depression and protrusion of the mandible.
- When the jaws close, both elevation and retraction of the mandible occur. Thus the natural opening and closing of the jaws involve a combination of gliding and rotational movements of the TMJs in their respective joint cavities.
- The disc plus the condyle glides on the articular fossa in the upper synovial cavity, moving forward or backward on the articular eminence.
- At approximately the same time, the mandibular condyle rotates on the disc in the lower synovial cavity
21
Q
Why is understanding joint movement important?
A
- Clients may have temporomandibular disorder (TMD)
- Thus dental professionals must understand the anatomy, histology, and normal movements of the TMJ before being able to understand any possible disorders associated with the joint.
22
Q
Describe the relationship between the muscles of mastication and the TMJ
A
- Four pairs of muscles attached to the mandible: the masseter, temporalis, medial
pterygoid, and lateral pterygoid muscles. - The muscles of mastication are responsible for closing the jaws, moving the mandible forward or backward, and shifting the it to one side.
- These jaw movements involve the movement of the mandible, while the rest of the skull remains relatively stable.
- RDHs need to understand the association of the muscles of mastication with the movements of the mandible: depression, elevation, protrusion, retraction, and lateral
deviation. - All the muscles of mastication are innervated by the mandibular division of the fifth cranial (trigeminal nerve).
23
Q
Protrusion involves the bilateral contraction of both of the _________ muscles
A
lateral pterygoid
24
Q
Describe the muscles and movements associated with retraction of the mandible
A
- The contraction of the posterior parts of both temporalis muscles are involved during retraction of the mandible.
- The rotational movement of the TMJ occurs mainly between the disc and the mandibular condyle.
- The rotation of the disc allows for movements which are depression or elevation of the mandible.
25
The ________ muscles are involved in depressing the mandible when they bilaterally contract during opening of the jaws with the __________ stabilized by the other ____________.
1. anterior suprahyoid
2. hyoid bone
3. hyoid muscles
26
Describe the resting position of the TMJ
1. The resting position of the TMJ is not with the teeth biting together.
2. Instead, the muscular balance and proprioceptive feedback allow a physiologic rest for the mandible, an interocclusal clearance /freeway space, which is approximately 2 to 4 mm between the opposing teeth of each dental arch.
27
What are the clinical considerations for the TMJ?
1. The history for a client may include questions about unusual growth patterns, previous injuries, illnesses, musculoskeletal complaints, and possible emotional disturbances.
2. Identifying the causes of TMJ have been a
clinical and diagnostic challenge in dentistry
for many years.
3. Most studies suggest that clinically significant TMD-related jaw pain, dysfunction, or both affects about 5% of the general population.
28
Describe Auscultation and Palpation of the TMJ
1. The TMJ can be palpated just anterior to each ear.
2. The articulation of the temporal bone and the mandible
Technique
1. Stand behind client.
2. Place index fingers just in front of the
tragus of each ear.
3. Ask client to open and close
4. As mouth opens, your fingertips will
drop into the joint spaces.
5. Place fingertips over joints and palpate as client slowly opens and closes several times and moves the mandible through the entire
range of motion
6. Note any deviations during opening
7. Listen for joint noises related
to mandibular movement - clicking and popping
29
How do you measure adequate opening of the mouth
1. Ask the client to place the index, middle, and ring fingers of one hand between the incisal edges of the upper and lower incisors.
2. The client’s own fingers are proportional to his/her jaw and are a good indication of adequate opening.
3. If the opening is less than 3 finger widths measure the interincisal opening
30
Describe normal function of the TMJ
1. Smooth motions as the jaw is moved
2. Symmetrical movement
3. No discomfort
31
What are notable findings of TMJ function?
1. Abnormal sounds (popping, clicking)
2. Grating sensations as the jaw opens and closes (crepitus)
3. Asymmetrical movements
4. Limited range of movement (three fingers do not fit in mouth)
5. Tenderness or pain reported by the patient
32
Describe TMD
1. In a healthy joint, the surfaces in contact with one another (bone and cartilage) do not have any receptors to transmit the feeling of pain.
2. Clients may have a disorder associated with one or both of their TMJs, or a temporomandibular disorder (TMD) (or dysfunction).
3. May experience chronic joint tenderness, swelling, and painful muscle spasms.
4. May also have difficulties in moving the joint, such as a limited or deviated mandibular opening.
5. TMD is a heterogeneous, complex disorder involving many factors such as - behavioral stressors; parafunctional habits -clenching and/or bruxism (grinding).
6. Trauma to the jaw may cause TMD with the disc having adhesions to the bony surfaces; however, stressors and habits are more common etiologic factors.
33
What are some common behavioural contributors to TMD?
1. Jaw thrusting (causing unusual speech and chewing habits) and excessive gum chewing or nail biting, as well as the size of food eaten
2. Poor posture can also be an important factor in TMJ symptoms - For example, holding the head forward while looking at a computer all day strains the muscles of the face and neck.
34
Not all client with TMD have abnormalities in the joint disc or the joint itself; most symptoms seem to originate from the _________
muscles.
1. When receptors from one of these areas are triggered, the pain causes a reflex to limit the mandible's movement.
2. Furthermore, inflammation of the joints can cause constant pain, even without movement of the jaw.
35
Muscle pain can sometimes be associated with muscle tissue trigger points, which is known as ________
myofascial pain dysfunction syndrome.
1. These trigger points can be localized by digital palpation, both intraorally and extraorally.
2.
36
Studies do not support the role of TMD in directly causing ________
headaches, neck pain, or back pain or instability.
However, cyclic episodes of TMD and other incidents of chronic body pain are commonly encountered in the population with TMD.
37
How is TMD diagnosed?
1. Recognition of TMD includes palpation of the joint as the patient performs all the movements of the joint as well as the associated muscles of mastication.
2. All signs and symptoms related to the TMD, such as the amount of mandibular opening and facial pain, should be noted in the client record, as should any parafunctional habits and related systemic diseases.
3. Many controversies surround the treatment of TMD, and fewer than half of client with TMD seek treatment for their disorder.
38
Most recent studies have determined that _________ and _________ are not involved in most cases of TMD, but lack of overbite may be additive factor.
1. malocclusion
2. occlusal discrepancies
Thus occlusal adjustment, jaw repositioning jaw, and orthodontic treatment are not the treatments of choice for all patients with TMD, nor do these treatments seem to prevent TMD.
39
Describe treatment for TMD
1. Most cases of TMD improve over time with inexpensive and reversible
treatments, including client-based or prescription pain control, relaxation therapy, stress management, habit control, moderate home-based muscular exercises, and orofacial myology.
2. Many of the homecare steps to treat TMJ problems can prevent such
problems in the first place; these homecare steps include avoiding hard
foods and chewing gum, learning relaxation techniques to reduce overall
stress and muscle tension, and maintaining good posture, especially
when working at a computer. Pause often to change position, resting
hands and arms, and relieve stressed muscles. It is always important to
use safety measures to reduce the risk of fractures and dislocations.
40
Describe the role of imaging in the diagnosis of TMD
1. To aid in diagnosis, traditional skull radiographs are taken.
2. In more severe cases, magnetic resonance imaging (MRI) of the joint may be requested since this non-invasive procedure for imaging soft tissue uses no ionizing radiation.
41
Describe oral appliances in the treatment of TMD
1. A flat plane full-coverage oral appliance(e.g.,a non-repositioning stabilization splint) often is helpful to control
2. Bruxism appliances can take stress off the TMJ, although some individuals - however may bite harder on it, resulting in a worsening of their condition
3. The anterior splint, with contact at the front teeth only, may then prove helpful if used short-term. These less inexpensive and reversible treatments, meaning the treatment should not cause permanent jaw or dentition changes, are now showing the same success as more expensive and irreversible treatments such as surgery.
4. These may relax muscles, protect dentition, stabilize and protect the joint, and provide biofeedback by making patients aware of their bruxing habits or by relieving the load on the disk.
42
Describe surgery for TMD
1. Only a few clients with TMD require surgery or other extensive treatment.
2. Surgery of the TMJ can now make use of arthroscopy with an endoscope and lasers.
3. Replacement of the jaw joint(s) or disc(s) with TMJ implants is
considered as only a treatment of last resort.
43
Describe acute episodes of TMD (subluxation)
1. An acute episode of TMD can occur when a client opens too wide, causing maximal depression and protrusion of the mandible, as when yawning or receiving prolonged dental care.
2. This causes subluxation, or partial dislocation of both joints.
3. Subluxation occurs when the person tries to close and elevate the mandible; the condylar heads cannot move posteriorly because the bony relationships prevent it and the muscles have become spastic.
4. The immediate symptom can be a loud crunch noise occurring right up against the ear drum, except the sound is produced on the inside of the head and not only seems like bones are breaking, but feels like it too.
5. This is instantly followed by excruciating pain, particularly in the side where the dislocation occurred.
44
What are the short term and long term symptoms of subluxation?
1. Short-term symptoms can range from mild to chronic headaches and muscle
tension or pain in the face, jaw, neck, shoulders, back, arms, and often in the legs.
2. Long-term symptoms can result in sleep deprivation, tiredness/lethargy, frustration, bursts of anger, difficulty performing everyday tasks, depression,
social issues relating to difficulty talking, hearing sensitivity (particularly to
high-pitched sounds), tinnitus, and pain associated with posture while at a
computer and reading books from general pressure on the jaw and facial
muscles when tilting head down or up.
3. The client may also notice a sharp bolt of pain shoot down the body when
the head is turned suddenly; this may be associated to the side of the jaw which is dislocated
45
What is the treatment for subluxation
1. Treatment of subluxation consists of relaxation of these muscles and careful movement of the mandible downward and back.
2. These clients must in the future refrain from extreme depression of the mandible such as what can occur with prolonged dental work.
46
Describe trismus
1. Trismus (lockjaw)is a painful condition in which the jaws do not open fully i.e.,(chewing muscles of jaw become contracted and inflamed, preventing the mouth from wide opening
2. Along with the pain, trismus can lead to serious health problems including difficulty in speaking, reduced nutrition and compromised oral hygiene.
3. Trismus can also occur with odontogenic infections
4. Trismus can result from trauma, oral surgery, radiation treatment and even TMJ problems. The limitation in opening mouth may be the result of joint damage, muscle damage, growth of connective tissue or combination of these factors.
