Joints Flashcards
Classification of mobility of joints
- Mobility is the amount of movement at a joint; it is dependent on the type of materials joining bones and the articulating surfaces of the bones
- Joint classification based on mobility
- Synarthrosis
- Amphiarthrosis
- Diarthrosis
What is Synarthrosis?
Synarthrosis (syn = together, arthro = joint): immobile; mostly axial
What is Amphiarthrosis?
Amphiarthrosis (amphi = of both kinds): slightly moveable; mostly axial
What is Diarthrosis?
Diarthrosis (di = two): freely moveable; mostly appendicular
How are joints classified?
- Structural classification of joints is based on the type of material that binds the bones together and whether or not there is a joint cavity
1. Fibrous
2. Cartilaginous
3. Synovial
Which types of joints have joint cavities
-Synovial joints have joint cavities
- cartilaginous and fibrous do not have joint cavities
What is the construction of fibrous joint?
Dense regular CT connects bones
What is the construction of Cartilaginous joint?
Cartilage connects bones
What is the construction of Synovial joints?
Ligaments and articular capsule connect bones;
ends of bones covered with articular cartilage
What are sutures?
Fibrous Joints: Sutures
* Synarthrotic
* Connected with short dense regular CT fibers
* Example:
- Sutures (= “seams”) between bones of skull
* Allow for skull growth
* During middle age, skull bones fuse together
What are Syndesmoses?
Fibrous Joints: Syndesmoses
* Syndesmoses = “with ligament”
* Amphiarthrotic (most)
* If longer fibers, more movement
* Dense regular CT fibers, longer than with sutures
* Typically found between long bones
* Examples
-Ligament between distal tibia and distal fibula
- Interosseous membrane between radius and ulna
What are Gomphosis?
Fibrous Joints: Gomphoses
* Gomphosis = “bolt” (peg-in-socket
joint)
* Synarthrotic
* Periodontal ligaments attach tooth
to bone of socket
What are Synchondroses?
Cartilaginous Joints: Synchondroses
* Synchondrosis = “junction of cartilage”
* Synarthrotic - do not move
* Bones united by hyaline cartilage
* Examples
- Epiphyseal plates
- Joint between first rib’s costal cartilage and manubrium of sternum
What are Symphyses?
Cartilaginous Joint: Symphyses
* Symphysis = “growing together”
* Amphiarthrotic
* Bones united by fibrocartilage pad (both strong and flexible)
* Examples:
-Intervertebral discs
- Pubic symphysis
What are the general characteristics of Synovial Joints?
- Synovial = “joint eggs”
- Diarthrotic = freely movable
- Synovial joints have
- Ligaments
- Joint Cavity
- Articular capsule
- - Fibrous layer
- - Synovial membrane - Synovial fluid
- Nerves
- Blood supply
Synovial Joints - Ligaments
Ligaments connect bone to bone
* Made of dense regular CT
* Can be within or external to joint capsule
Synovial Joints- Joint Cavity
Joint Cavity
* Potential space with a small amount of
synovial fluid
Synovial Joints - Articular capsule
Articular capsule (joint capsule)
* Outer fibrous layer
* Inner synovial membrane
* Fibrous layer: dense irregular CT, continuous with periosteum
* Synovial membrane
* Inner lining of capsule and all other internal joint surfaces not covered in cartilage
* Loose CT, vascular
* Produces synovial fluid
* Synovial fluid is a lubricant within the capsule
Synovial Joints - Synovial Fluid
Synovial fluid
* Blood filtrate, is viscous
* Glycoproteins make fluid slippery, easing movement of joint
* Found in articular cartilages as well as in cavity
- Pressure placed on cartilages causes synovial fluid to move in and out of articular cartilages = weeping lubrication
- This nourishes the chondrocytes in the articular cartilage (important because it is avascular)
Nerves purpose in Synovial Joints?
Nerves
* Articular capsule has rich supply of sensory
nerve fibers
* Some detect pain
* Some detect amount of stretch of joint capsule
- Tells body about proprioception
Blood supply purpose for Synovial Joints?
Blood supply
* Most supply synovial membrane (for
producing synovial fluid)
What are synovial joints with an articular disk?
Some synovial joints have an articular disc
* Disc of fibrocartilage
* Helps improve the fit of articulating cartilages
* Example: meniscus (= “crescent”) of the knee (more on this later…)
What is the labrum?
- Labrum increases stability in joint
- Glenoid labrum: lip of fibrocartilage around glenoid cavity
- Acetabular labrum: circular rim of fibrocartilage around acetabulum of hip joint
What are Bursae?
Synovial Joints: Bursae
* Bursa (= “purse”): closed fibrous sac lined with synovial membrane and filled with synovial fluid
- Reduces friction as parts move over each other
- Often where ligaments, tendons overlie bone
