Ch 8 - Joints Flashcards
Definition:
the site where two bones meet (may or may not allow movement)
Joints (articulations)
Functional Classification of Joints
1) Synarthoses - no movement
2) Amphiarthroses - some, limited movement
3) Diarthroses - free movement
Structural Classification of Joints
(type of tissue that connects bones)
1) Fibrous Joint: bones joined by collagen fibers of connective tissue
2) Cartilaginous Joint: bones joined by cartilage
3) Synovial Joint: (most joints) possess a joint cavity, diarthoses
Joint classification
Joint that allows no movement
Synarthroses
Joint classification
Joint that allows some, limited movement
Amphiarthroses
Joint classification
Joint that allows free movement
Diarthroses
Types of Fibrous Joints
1) Sutures - only between bones of skull
2) Syndesmoses - bones connected only by ligaments
3) Gomphoses - joins tooth to alveolar socket
Definition
Ossified Sutures in Adulthood
Syntoses
Examples of Syndesmoses
Ligament holding together Tibia and Fibula, Ulna and radius
Movement allowed depends on the lengths of the bands of the ligament
Ligament Involved in Gomphoses Joints
Periodontal ligament joins tooth to alveolar socket
Very little movement
Types of Cartilaginous Joints
1) Synchondroses - Joined by plate of hyaline cartilage
2) Symphyses - joined by fibrocartilage
Examples of Synchondroses Joints
1) Epithelial plate in long bones
2) Costal Cartilage
Mostly Synarthroses
Examples of Symphyses Joints
1) Intervertebral joints - discs can herniate & press against nerve/muscle
2) Pubic symphysis
Allows for some limited movement and provides support against pressure
6 Structures in all Synovial Joints
1) Articular cartilage: hyaline cartilage covering bone ends
2) Joint cavity: small space between articulating bones
3) Articular capsule: two-layered capsule that encloses joint cavity
4) Synovial fluid: slippery fluid occupying space in joint capsule & articular cartilages
5) Reinforcing ligaments: bandlike ligaments that join articulating bones
6) Innervation & vascularization: Joints supplied with sensory nerve fibers and lots of blood
What is the function of articular cartilage?
Prevent bones from rubbing against one another; Absorbs synovial fluid when joint in inactive
Layers of the Articular Capsule
1) Fibrous Layer - outer layer continuous with perioseum (prevents dislocation)
2) Synovial Membrane - inner layer, lines joint cavity (not at articular cartilage) - produce synovial fluid
Function(s) of synovial fluid
1) Protect articular cartilage, bone, and articular capsule from friction
2) Enter and exit articular cartilage depending on movement
When joint is inactive - fluid is viscous, thick, water taken up by articular cartilage, helps hold bones in place
When joint is active - fluid squeezes out of articular cartilage like a sponge into joint cavity, becomes churned up and thinned out - oily/watery - allows bones to slide
Why joints need nerve fibers (3)
1) Sensing pain - danger, last warning before break/injury
2) Pressure on the joint - tells CNS how much muscle strength is needed (back off before break/tear)
3) Stretch of joint - tells CNS angle joint is at (back off before break/tear)
Structures associated with synovial joints (2)
May or may not be present depending on complexity of the joint
1) Bursae (bag/purse) - sac if synovial fluid to protect structures that may come in contact with bone during joint movement
2) Tendon Sheath - elongated bursae that wraps completely around tendon that is subject to frequent friction (close together)
Ex. Bursae - Glenohumeral joint; bursae exists between head of humerus and muscle
Ex. Tendon Sheath - At wrists and angle as tendons are compacted closely together (forearm/calf wider than wrist/ankle)
Factors of Joint Stability (3)
1) Articular Surfaces: better fit = more stable, less flexibility
2) Ligaments: more ligaments = stronger joint, except if ONLY ligaments - weaker
3) Muscle Tone: muscles constantly pull on tendons that wrap around joint - “braces” joint (most important!!)
The more you have of each, the stronger/more stable, but the more stable the joint is, the less flexible it is
Types of movements allowed by Synovial Joints
1) Nonaxial movement - flat articular surfaces “plane joint,” gliding
2) Uniaxial movement - flexion/extension OR rotation, hinge/pivot joint
3) Biaxial movement - flexion/extension & a(b/d)duction, condylar/saddle joint
4) Multiaxial movement - Flexion/extension & a(b/d)duction & rotation, ball-and-socket joint
Type of joint found in intertarsal/intercarpal joints & movement
Plane Joint - nonaxial, allows for sliding
Type of joint found between humerus and ulna & movement
Hinge Joint - uniaxial, allows for flexion/extension
Type of joint found between radius and ulna & movement
Pivot Joint - uniaxial, allows for rotation
Type of joint found at knuckle & movement
Condylar joint - biaxial, allows for flexion/extension & a(b/d)duction
Type of joint found at base of thumb & movement
Saddle joint - biaxial, allows for flexion/extension & a(b/d)duction
Type of joint found at shoulder/hip joint & movement
Ball-and-socket joint - Multiaxial, allows for flexion/extension & a(b/d)duction & rotation
Type of joint
Temporomandibular joint (TMJ)
Modified hinge joint
- Articular disc divides synovial cavity into superior and inferior potrions
Inferior: allows elevation/depression
Superior: allows lateral excursion
Inferior: allows elevation/depression
Stabilizing the Glenohumeral (shoulder) joint
1) Reinforcing ligaments - very thin and loose
2) Rotator cuff - 4 muscles (and their tendons) that encircle the joint
3) Glenoid labrum - rim of fibrocartilage around glenoid fossa - prevents slipping out of joint
Ligaments: coracohumeral ligament & glenohumeral ligaments
Stabilizing the Elbow Joint
1) Close fit of trochlea and trochlear notch
2) Muscle and tendon of arm muscles wrap around joint
3) Ulnar collateral ligament (medial side) and radial collateral ligament (lateral side) prevent lateral movement
Stabilizing the Coxal Joint
1) Acetabulum of os coxa has acetabular labrum to deepen socket
2) Ligaments of articular capsule (iliofemoral, pubofemoral, and ischiofemoral ligaments)
3) Ligamentum teres - ligament of the head of the femur
Ligaments of articular capsule named after the bones they connect to - all bones of the os coxa
Joints of the Knee
Single joint cavity shared by 3 separate joints:
1) Femoropatellar joint - between patella and femur
2) Tibiofemoral joints - between femur and tibia (1 medial, 1 lateral)
Stabilizing the Knee
1) Menisci - thin layer of fibrous cartilage at outer margins of tibiofemoral joints
2) Extracapsular & capsular ligaments - prevent hyperextension
3) Intracapsular ligaments (cruciate ligaments) - ACL and PCL
Cruciate Ligaments:
Anterior cruciate ligament (ACL) - prevents forward sliding of tibia, prevents hyperextion - attaches anterior of tibia
Posterior cruciate ligament (PCL) - prevents backward sliding of tibia and forward sliding of femur - attaches posterior portion of tibia
Cruciate Ligaments
1) Anterior cruciate ligament (ACL) - prevents forward sliding of tibia, prevents hyperextion - attaches anterior of tibia
2) Posterior cruciate ligament (PCL) - prevents backward sliding of tibia and forward sliding of femur - attaches posterior portion of tibia
Types of Arthritis
1) Osteoarthritis (OA) - exposed bone rubs together, forming bone spurs
2) Rheumatoid arthritis (RA) - autoimmune chronic inflammatory disorder
Causes and effects of Osteoarthritis
Caused by more articular cartilage being destroyed than repaired
Effects: exposed bone rubs together, forming bone spurs
Bone spurs: bone ends deform, restricting movement at the joint
Causes and effects of Rheumatoid Arthritis
Autoimmune chronic inflammatory disorder
- joints of fingers, wrists, ankles, feet most likely to be affected
- Flare-ups followed by periods of remission
Pain and swelling felt in joints affected by RA during flare ups
During periods of remission - no pain/swelling in joints affected by RA
Thin layer of fibrous cartilage at outer margins of tibiofemoral joints
Menisci
