Temporomabndibular joint, muscles and their function (oral ana.)

TMJ stands for

TemporoMandibular Joint

Mandibular Condyle’s blood supply?

no blood supply

Describe Mandibular Condyle

fibrous and avascular

Mandibular Condyle position

maximum intercuspal

what is maximum intercuspal?

is in the position it would occupy when the teeth fit together as tightly as possible

ARTICULATING FOSSA aka

glenoid fossa or mandibular fossa

articulating fossa location

Portion of mandibular fossa that is anterior to the petrotympanic fissure

articulating fossa function

non-functioning portion of TMJ

ARTICULATING EMINENCE aka

transverse bony ridge

articulating eminence location

Anterior and inferior to articular fossa

articulating eminence function

functioning portion of TMJ

what is articulating disc

Oval pad of dense fibrous connective tissue; NOT A BONE

articulating disc location

space between the mandibular condyle and articular fossa

articulating disc acts as?

shock absorber betqeen the mandibular condyle and articulator fossa and articulator eminence

articulating disc functions as

“cushion” between articulating bones

articulating disc blood supply?

no blood supply

characteristics of articulating disc

• The disc surfaces are very smooth

• Each disc is thinner in the center than around the edges

• Upper surface is concave anteriorly to conform to the convex articular eminence; it is convex posteriorly to confirm to the concave shape of the articulating fossa that it loosely rests against.

what does articulating disc divides

space between the head of the condyle and the articulating fossa into upper and lower spaces

what kind of movements does articulating disc permit

complex functional movements

anterior and posterior portions of the disc contain specialized nerve fibers are called

proprioceptive fibers

proprioceptive fibers helps with

unconsciously determine the position of the mandible, and therefore help regulate the movements of the mandible

articulating disc stabilizes the condyle by

filling the space between incongruous articulating surfaces of the convex condyle and concave-convex articulating fossa and articular eminence

articulating disc cushions the articulating bones of the joint at the areas of contact like a

shock absorber

the articulating disc cushion and lubricates to

reduce physical wear and strain on joint surfaces

Capsular Ligament aka

fibrous capsule

capsule ligament encloses

encloses the TMJ

what is synovial membrane

Lines the internal surface of fibrous capsule that surrounds the bones and their articulating surfaces

capsular ligament secretes what? And what is that fluid for?

Secretes synovial fluid. Synovial fluid lubricates joint and is the source of nutrition

what is the bilaminar zone

A thick pad of loose elastic vascular connective tissue where the the disc and the fibrous capsule is connected on the posterior segment of the TMJ

Lateral ligament attaches to and directed?

Attaches to the zygomatic arch and is directed obliquely down and posterior to the lateral and posterior neck of the condyle.

Stylomandibular Ligament attached to

styloid process → angle of the mandibular

relaxed

if mouth is closed

tensed

if mandible is in extreme protrusion

Sphenomandibular Ligament help with

Help limit maximum opening of the jaw

Sphenomandibular Ligament attached

superiorly to the angular (sphenoid) spine of the sphenoid bone and fans out inferiorly to attach on the lingula of the mandible near the mandibular foramen

elevation

closing the mouth

depression

opening the mouth

retrusion

Retracting or pulling back of the mandible posteriorly

potrusion

Protracting of moving the mandible anteriorly

lateral excursion

Moving the mandible sideways, as when chewing

masseter

Most superficial, bulky and powerful among all the muscles of mastication

temporalis

A fan-shaped, large but flat muscle with both vertical anterior (and middle) fibers and more horizontal posterior fibers.

what two muscles serve as a sling with the medial pterygoid attached on the medial side and the masseter attached on the lateral side of the angle of the mandible

masseter and medial pterygoid

lateral pterygoid

prime mover of the mandible

lateral pterygoid can’t move how?

closing of the jaw

MASSETER origin

Inferior and medial surfaces of zygomatic arch

masseter insertion

Inferior and lateral surface of the ramus and angle of the mandible

masseter action

elevates the mandible (closes the mouth) -Applies great power in crashing food

temporalis origin

entire temporal fossa

temporalis insertion

• coronoid process of the mandible

• Medial surface of the anterior border of the ramus

• Temporal crest of the mandible via one common tendon

temporalis action

• Anterior (and Middle) vertical fibers – contract to act to elevate the mandible

• Posterior horizontal fibers retrude or pull the mandible posteriorly

medial pterygoid origin

Medial surface of the lateral pterygoid plate and the pterygoid fossa

medial pterygoid insertion

• medial surface of the mandible in a triangular region at the angle and on the adjacent portions of the ramus just above the angle

medial pterygoid action

elevates the mandible

lateral pterygoid origin

• Smaller superior head Attached to the infratemporal surface of the greater wing of the sphenoid bone

• Larger inferior head Attached to the adjacent lateral surface of the lateral pterygoid plate on the sphenoid bone

lateral pterygoid insertion

the pterygoid fovea and into the anterior margin of the articular disc.

Depression on the front of the neck of the condyloid process called

pterygoid fovea

lateral pterygoid action when BOTH lateral pterygoid contract

• protrude the mandible • depress the mandible

When only one lateral pterygoid contracts (action)

• pulls the condyle on that side toward the midline (medially) and anteriorly

• Moving the mandible and its teeth toward the opposite side