supportive structures Flashcards
(36 cards)
Which direction do the fibers of the periodontal ligament run?
obliquely from cementum in a cervical direction to bone
what is the name of the anterior and posterior process of the mandible?
Anterior= coronoid process posterior= condyle
What bony structure is located posterior to the mandibular fossa? Which direction does it run?
Squamotympanic tissue which extends mediolaterally
What does the squamotympanic fissure divide into and in what directions?
As the squamotympanic fissure extends medially it divides into the petrosquamous fissure anteriorly & petrotympanic fissure posteriorly.
what is a ginglymoid joint?
Hinge joint
What is an arthrodial joint?
glinding joint
What type of joint is the TMJ considered? (three different names for diff classifications)
1) Ginglymoarthrodial joint (gliding & hinge)
2) Compound joint (requires presence of at least three bones) The articular disc serves as a nonossifed bone to make up the third of the TMJ
3) Synovial joint
what is the articular disc composed of?
Dense fibrous CT & has NO blood vessels or nerves (the extreme periphery of the disc is slightly inn)
What is the articular disc attached to posteriorly? Anteriorly?
Posteriorly= Region of loose CT that is highly vascularized & inn called RETRODISCAL TISSUE Anteriorly= many elastic fibers--sup. retrodiscal lamina
what type of fibers make up the inferior retrodiscal lamina?
collagenous (elastic for superior retrodiscal lamina)
Which part of the disc attaches to the capsular ligament?
Superior & inferior attachments of the anterior region of the disc. Also medially and laterally–divides joint into two distinct cavities.
What are the two mechanisms in which synovial fluid lubricates the articular joint?
1) Boundary lubrication–joint moved & fluid moved in cavity–prevents friction & is primary mech. of lub.
2) Weeping lubrication–articular surface absorbs small amount of synovial fluid. Small amount is drawn out of surface during function (metabolic exchange–NOT for moving of joint, but compression)
What are the four zones of the articular surfaces of the mandibular condyle?
1) Articular (dense fibrous CT, with stand movement, better ability for repair than hyalin)
2) Proliferative (cellular, undiff. mesenchyme)
3) fibrocartilaginous (collagen fibrils-resist compressive & lateral forces)
4) calcified cartilage (chondrocytes & blasts for remodeling)
What arteries supply the TMJ?
1) superficial temporal A
2) Middle meningel A (posterior supply)
3) internal maxillary A from inferior.
What supplies the condyle with blood?
Inferior alveolar A
What are ligaments made up of?
Collagenous CT (do not stretch--can be elongated over time which alters joint function)
What are the five functional ligaments that support the TMJ?
1) collateral
2) capsular
3) temporomandibular
2 accessory ligs:
4) sphenomandibular
5) stylomandibular
What do the collateral ligaments do?
Attach medial & lateral borders of disc to poles of condyle (there are two–“collateral”) Divide the joint mediolaterally into sup & inf cavities. RESTRICT movement AWAY from CONDYLE
***hinging movement of TMJ.
What does the capsular ligament do?
Surrounds entire TMJ.
Resist medial, lateral, inferior forces that would dislocate surfaces.
Retains synovial fluid
Proprioceptive feedback of joint.
What does the temporomandibular ligament do?
Two parts: outer oblique and inner horizontal.
Oblique–resists dropping of condyle & limits opening
Horizontal–limits posterior movement of condyle & disc. Protects retrodiscal tissues & lateral pterygoid mm from over extension.
What does the sphenomandibular ligament do?
One of two accessory ligaments.
Attachment: spine of sphenoid–> lingula
No sig. limiting effects
What does the stylomandibular ligament do?
One of two accessory ligaments.
Attachment: styloid process–> angle ramus
Limits excessive protrusive movements.
T/F Fast or type II mm fibers have more mitochondria?
FALSE: Fast fibers have fewer mitochondria and rely more on anaerobic activity. They are capable of quick contraction but fatigue more rapidly. Slow fibers or type I have well-developed aerobic metabolism and resist fatigue.
What are the four mm of mastication?
Masseter, temporalis, medial & lateral pterygoids
