Anatomy of Masticatory structures Flashcards
describe the TMJ joint
hinging movements in one plane (ginglymoid joint) and gliding movement in another plan (arthrodial joint)
what type of joint is the TMJ
a ginglymoarthrodial joint
with initial opening of the TMJ, the condyle _______
rotates or hinges
with wide opening the TMJ, ______ movement occurs
translation or gliding
the middle of the condyle should reach the summit of the articular eminence with:
maximum opening
articulation is between:
the cranium and the mandible
what does the TMJ capsule contain
a fibrous capsule contains the synovial fluid and maintains the relationship between the joint components
what does the synovial fluid do
transports nutrients to and waste products from the articular surfaces and lubricates joint
synovial fluid is secreted by? and how much is in the joint space
the membrane lining the synovial joint and there is approximately 1cc in each compartment of the joint spaces
the disc separates what?
the condyle and mandibular fossa from direct contact and divides joint into superior and inferior joint spaces
what are the functions of disc
- distributes loading forces
- decreases wear
- stabilizes condylar movement
the disc is composed of:
dense fibrous connective tissue NOT cartilage
can the disc repair itself
the disc has some ability to repair itself
where is the disc devoid of nerves and where does it articulate
in the intermediate zone which articulates with the supererior aspect of the condyle
what is the histology of the disc of the TMJ
- dense, fibrous CT
- non vascular in center
- non innervated in center
what is the histology of the posterior attachment
- loose, vascular CT
- richly innervated (auriculotemporal nerve)
what is the posterior attachment called
retrodiscal tissue
the articulating surfaces are lined with:
dense fibrocartilage
what is the importance of the dense fibrocartilage lining the articulating surfaces
allows for a greater ability to heal
what covers the articulating surface of the bone
a thin layer of cartilage
what is the function of the articular cartilage
plays an important role as a stress absorber during function
the compressive loading of the articular cartilage is highest in the:
anteromedial region of the condyle
what is the articular cartilage composed of
cells and ECM
what do discal ligaments do
allow disc to move in anterior posterior direction during condylar translation
discal ligaments may become inflamed and painful because:
they are vascularized and innervated
what does the maxillary artery supply
medregion of face
what do the sphenomandibular ligament and sytlomandibular ligament do
limits inferior movement of mandible
what is the vascular supply to the TMJ
- superficial temporal artery: transverse facial
- maxillary artery: deep auricular, masseteric, posterior deep temporal
what is the nerve supply to the TMJ
- auriculotemporal (V3) nerve
- masseteric nerve
what are the masticatory muscles
- masseter
- medial pterygoid
- temporalis
- lateral ptyergoid
- digastric muscle
what muscles work to elevate (close) the mandible
- masseter
- medial pterygoid
- temporalis
what does the lateral pterygoid do
assists in protrusion (inferior head) and stabilizes the disc/condyle complex ( superior head)
what does the digastric muscle do
assists in depression (mouth opening) and retrusion
what are the functional behaviors of the masticatory muscles
talking, chewing and swallowing
what are the nonfunctional behaviors of the masticatory muscles
- bruxism, clenching or empty mouth chewing movements
what is the innervation of the masticatory muscles
V3 mandibular nerve
what does the superficial masseter muscle do
elevates the mandible (closes the jaw)
what does the deep masseter muscle do
retrudes the mandible
what are the actions of the temporalis muscle
- closes the jaw
- retrudes the jaw (with posterior and middle fibers)
- deviates the jaw to the same side
what are the actions of the medial pterygoid msucle
- deviates the jaw to opposite side
- helps to elevate the mandible in concert with masseter and temporalis muscles
- assists the lateral pterygoid in protrusion
what does the superior division of the lateral pterygoid muscle
pulls disc forward and check-reins its backwards movement and assists in closing jaw
what does the inferior division of the lateral pterygoid muscle do
- protrudes and depresses (opens) the mandible
- deviates jaw to opposite side
what are the digastric muscle actions
- depresses (opens) and retrudes the mandible
what are TMD disorders
a collective term that includes a number of clinical problems that involve the masticatory muscles, TMJ and associated structures
what are the 3 TMD groups
- musculoskeletal disorders
- articular disc disorders
- inflammatory and non inflammatory disorders
