Tmj Flashcards
•transverse ridge of dense bone
• strongly convex in the sagittal plane
•tilted down at an angle of approximately 25° to the occlusal plane
•the anterior limit of the articular/mandibular /glenoid fossa
• forms most of the articular surface of the mandibular fossa.
•Extends out laterally to the zygomatic arch as the articular tubercle
• provides a surface over which the mandibular condyle glides during mandibular movements
Anterior tubercle/eminence
•is a thin-walled, smooth, concave depression in the temporal bone
• is most easily inspected when the mandible is removed.
••the zygomatic arch extends laterally in front of the fossa and a distinct ridge, the articular eminence, lies anterior to the fossa.
•formed entirely by the squamous portion of the temporal bone
•as the zygomatic process of the temporal bone passes posteriorly, it widens to form the articular tubercle of the mandibular fossa anteriorty.
•lined by articular tissue that extends anteriorly beyond the articular summit onto the preglenoid plane
Articular (glenoid/Mandibular) fossa
thin and often translucent when held to the light (confirmation that it is not a major load-bearing
area of the joint).
Roof of the fossa
formed by the tympanic plate, which also forms the anterior wall of the external acoustic meatus.
Posterior wall
Structural features of synovial joints
1Articular cartilage
2. Joint (articular) capsule
3. Articular (synovial)cavity
4. Presence of accessory / additional structures within the area enclosed by the capsule
• serves as a lubricant between the bony articular surfaces
•also aids metabolite transport to cells in the articular cartilages
•synthesized by the synovial membrane that lines the joint capsule.
Synovial fluid
the articulating surfaces of the skeletal elements
(bones) is covered by a layer of cartilage
(usually hyaline)
Articular cartilage
consisting of.
outer fibrous membrane inner synovial membrane
Joint (articular) capsule
> interlacing bundles of parallel fibers of collagen type I that completely encloses each synovial joint (except where it is interrupted by synovial protrusions
• is attached continuously round the ends of the articulating bones.
Fibrous capsule
•perforated by vessels and nerves
• may contain apertures through which synovial membrane protrudes as bursae.
•lined by a synovial membrane that also covers all non-articular surfaces (bones, tendons and ligaments) that lie partly or wholly within the fibrous capsule.
Fibrous capsule
Lines the
• fibrous joint capsule
•exposed osscous surfaces
• intracapsular ligaments, bursae and tendon sheaths
Synovial membrane
• does not cover intra-articular discs or menisci
•stops at the margins of articular cartilages in a transitional zone that occupies the peripheral few millimetres of cartilage.
•secretes and absorbs a fluid that lubricates the movement between the articulating surfaces.
Synovial membrane
•Pink, smooth, shiny
•Displays a few small synovial villi that increase in size and number with age.
•Synovial villi are more numerous near articular margins and on the surfaces of folds and fringes, and become prominent in some pathological states.
Internal Synovial surface
• Folds and fringes of membrane may also project into a joint cavity; some are sufficiently constant to be named, c.g. the alar folds and ligamentum mucosum of the knee.
• Accumulations of adipose tissue (articular fat pads) occur within the synovial membrane in many joints.
Internal synovial surface
Two layers sinovial membrane
•Intimal layer (highly cellular ) resting on a fibrous
• subintimal layer (vascular) (subsynovial tissue).
•These pads, and also synovial folds and fringes
• are deformable cushions that occupy potential spaces and irregularities in joints that are not wholly filled by synovial fluid.
• they accommodate to the changing shape and volume of the irregularities during movement, a function they share with intra-articular discs and menisci.
Internal synovial surface
•they also increase the area of synovial membrane, and may help to spread synovial fluid over the articular surfaces.
Internal synovial surface
Closed sacs of synovial membrane that occur outside joints
Synovial Bursae
Tendon Sheaths
Synovial bursae
•reduce the friction of one structure moving over the
other
•often intervene between structures, such as
tendons and bone tendons and joints skin and bone
•Connective tissue sac that surround a muscle tendon at places where the tendon crosses a joint.
•contains a lubricating fluld that allows for smooth
motions of the tendon during muscle contraction and joint movements.
Reduce friction
Tendon sheaths