Joints Flashcards
Definition of Joints
The place of union between: • two or more bones • two or more cartilages • bone and cartilage • Amount of movement varies from none to highly mobile. • May or may not include a fluid filled space between the bones. • Shape and tissue composition of the articulating surfaces is variable.
Structural Classification
• Fibrous
- Suture (non moveable and only in skull) - Syndesmosis (limited movement ex. radius and ulna) - Gomphosis (limited movement in only peridontal lig)
• Cartilaginous
- Symphysis - Synchondrosis
• Synovial
- Simple - Complex - Compound
Joint Development
Start with condensation of mesenchyme
Then a space opens called the interzonal space which can grow 1 of 3 ways:
1) space filled with FIBROUS tissue (fibrous joint)
2) Fibrocartilage in the space - cartiaginous joint
3) Empty space = synovial joint
Symphysis
Two bones are connected by a flattened disc of
fibrocartilage.
• E.g. Pubic symphysis,joints between the vertebral bodies, mandibular symphysis (which fuses to become a synostosis).
Synchondrosis
• Temporary joint between bones, where hyaline
cartilage intervenes before eventual fusion.
• E.g. between epiphysis and diaphysis of a long
bone, between sphenoid and occipital bones, at
the acetabulum.
Synovial Joint
Permit free movement.
• Can be simple, complex or compound.
• Bones that contact each other have
articular surfaces covered in hyaline cartilage.
• Joint is held together by ligaments and a capsule.
• The capsule is lined by a synovial membrane that secretes a lubricating
synovial fluid.
Simple Synovial
2 articulating surfaces
• 1 joint cavity
• where ribs hit vertebra
Presence of hyaline ARTICULAR CARTILAGE
synovial mem. lining all surfaces expt. articular cartilage
Structures associated: Fibrous joint capsule • Synovial membrane • Articular disc/meniscus • Fat pads • Bursa • A closed sac filled with synovial fluid, present in places of friction
• Ligaments (intra- or extracapsular)
Complex Synovial
2 or more articulating surfaces • 1 or 2 joint cavities • Disc or meniscus partly or fully separating joint cavity into two • E.g. TMJ, knee
Compound
3 or more articulating surfaces
• E.g. in the wrist
Movement at Synovial
Uniaxial • Hinge (ginglymus) • Humeroulnar • Pivot (trochoid) • Humeroradial • Gliding (arthroidal) • Carpal
Biaxial
• Ellipsoid
• Radiocarpal
Multiaxial
• Ball and socket
(spheroid)
• Hip and shoulder
TMJ
Complex synovial joint articulating between mandible and temporal bone
Lower compartment is a hinge (ginglymus) • Upper compartment glides (arthroidal) = ginglymoarthroidal joint
TMJ Capsule
Encloses joint space
• Superiorly attaches around mandibular fossa and to articular eminence
• Inferiorly, the capsule is attached to the mandibular neck
• The capsule is also attached to the disc
• Limits movement of the disc and condyle
Temporalmandibular Ligament (Lat. lig)
From lateral surface of eminence and
articular tubercle to lateral aspect of the condyle and the mandibular neck
• Restricts posterior and inferior displacement of the condyle on ipsilateral side
• Restricts medial movement
• Restricts lateral movement of
contralateral side
Sphenomandibular Ligament
From sphenoid spine to the lingula of the mandible
• Limits depression of mandible to prevent dislocation
• Slack when mandible is elevated and becomes taught when
depressed
• Also limits lateral movement
Stylomandibular Ligament
From the styloid process to the angle of the mandible
• Limits depression of mandible to
prevent dislocation
• Limits protrusion
