TMJ/masticatory system Flashcards
What is TMJ?
It is a unique joint that contains 2 joint spaces separated by a fibrocartilage disc.
The non articulate surfaces are lined by a synovial membrane which produces synovial fluid that lubricates the joint.
The joint is supported by ligaments which surround the joint capsule.
Describe the condyle?
Articulating surface covered by thin layer of fibrocartilage, lateral ptyergoid attaches below ridge running medial laterally on anterior surface of condyle.
Describe the glenoid fossa?
Found on the interior surface of the squamous temporal bone where fossa is covered by thin layer of fibrocartilage
Describe the inter articular disc?
Biconcave sheet of vascular fibrous CT which divides the joint space into superior and inferior joint space.
It blend with margins of lateral ptyergoid muscle anteriorly and posteriorly attached to bilaminar zone which consist of loose CT and contains nerves lined by synovial membrane
Describe the capsule
Thin fibrous CT attached to articulate eminence of the fossa, articulate disc and neck of the mandibular condyle. The disc attached to it medial and laterally.
The lateral aspect are thickened by the TMJ ligament
Describe the retrodiscal tissue
The tissue is vascular and highly innervated which is the major contributor to pain of TMD partially when there is inflammation or compression of the joint
Describe the TMJ ligaments
The lateral ligament lies lateral to the TMJ and runs from the root of the zygomatic to the posterior aspect of condylar neck. It limits anterior posterior joint movement.
The sphenomandibular and stylomandibular ligaments also limit movement.
What is the TMJs bloody supply?
Deep auricular artery - branch of maxillary artery
What is the TMJs nerve supply?
Auriculotemporal, masseteric and posterior temporal nerves
What muscle is responsible for protrusion of mandible?
Lateral pterygoid
What muscles are responsible for retraction of mandible?
Geniohyoid and digastric muscles
What muscles are responsible for depression of mandible?
Digastric, geniohyoid and mylohyoid muscles along with gravity
What muscles are responsible for elevation?
Temporalis, masseter and medial pterygoid muscles
What is the prevalence of TMJD?
10-30% of individuals but only 15% seek help
3rd most common chronic pain syndrome
What are the 3 categories of TMJD?
Arthritis
- inflammatory pathology
- RA
Arthrosis
- non inflammatory, mechanical derangement or degenerative diseases
- normal wear and tear
Musculoskeletal
- most common due to inflammation of masticatory muscles
What is the aetiology of TMJD?
Inflammation secondary to parafunctional Trauma\ Stress Psychogenic Occlusal abnormalities
What are the presenting signs and symptoms of TMJD?
Limited opening or trismus Clicking/joint noises Crepitus (arthritis changes) Jaw locking Headaches Preauricular pain Muscle/joint or ear ache
What are the management options for TMJD?
Reassurance
Conservative advice
- limiting jaw opening
- soft diet and small pieces
- no wide opening and support yawning
- no chewing gum/pens
- stopping parafunctional habits
- masticate bilaterally
Stress management
- relaxation
- CBT
- mindfullness
- exercise/massage
Physio therapy
- Acupuncture
- muscle manipulation
Pharmacotherapy
- NSAIDs
- diazepam
- antidepressants
Splint therapy
- full coverage splints
- soft splints
- stabilisation Michigan upper splint
Surgery
- arthrocentesis: flush out joint to break down adhesions
- arthroscopy - remove adhesions
- arthroplasty or joint replacement
Secondary care referral with multiple unsuccessful testaments
What is internal derangement of TMJ?
It is lack of coordinate movement between condyle and articulate disc as the condyle overcomes mechanical obstruction before full movement is achieved which caused clicking and possible jaw locking
What is temporal arteritis?
It is a form of vasculitis where the temporal arteries that supply blood to scalp become inflamed and constricted.
It is a multifactorial condition caused by jaw claudication as muscle ischaemia causes reduced arterial blood flow.
What are the red flag symptoms for temporal arteritis?
Cranial nerves dysfunction Severe weight loss Very sudden increase in pain Usually older >50yr patients with new onset of headaches Near absolute trismus Scalp tenderness
What is the management of temporal arteritis?
Urgent referral for US scan, biopsy and steroid treatment due to possibility of blindness or stroke.
What is the difference between disc displacement with and without reduction?
Disc displacement + reduction
- click +/- signs and symptoms of TMD
Disc displacement - reduction
- limited opening or without limited opening
A 58yr old female Pt complains of a dull, throbbing pain on right side of her face. When she removes glasses, she reports tenderness on the right side.
Haematological investigation reveals the ESR is 81mm/hr. what is the likely diagnosis?
Giant cell arteritis (temporal arteritis) due to increase in ESR
What limits the movement protecting the TMJ?
Ligaments pertaining to the joint limit movement
- stylomandibular, sphenomandibular, pterygomandibular ligaments
What do the periodontal mechanoreceptors do?
They influence the shape of posselt’s envelope.
They also evaluate intensity and direction of stress back to MoM
What should the SDA have?
At least 10 pairs of occluding teeth
What are the suprahyoid muscles?
Digastric
Mylohyoid
Geniohyoid
Stylohyoid
What are The infrahyoid muscles?
Thyrohyoid
Sternohyoid
Omohyoid
Sternothyroid
A patient had osteophytes and crepitus in TMJ. What is the likely cause?
Osteoarthritis/osteoarthrosis
In dentate Pts with minimal toothwear and in class I molar and incisal relationship, what tooth position is generally 0.5-1mm posterior to ICP?
Retruded contract position
- when mandibular condylar head is in its most superior, posterior position.
What best describes a mutually protected occlusion?
Working side contacts and posterior disclusion in protrusion.
How would you describe an occlusal contact on the opposite side to lateral excursive movements of the mandible?
Non working side interference
What is another name for the arc of movement when the condyle is rearmost and upper most in the glenoid fossa?
Terminal hinge axis
- Arc of closure when the condyle is in its most superior posterior position
What muscle differentiates the sublingual and submandibular tissue spaces?
Mylohyoid
What best describes the role of the masticatory muscles?
To primarily direct movement of the TMJ
What is the name of the side to which the mandible moves on lateral excursions?
Working side
What is the role of the lateral pterygoid muscle?
Protrusive movement and opening of the mandible
