Connective Tissue Biomechanics: Part II Flashcards
Introduction
- connective tissue is the building block of bone, ligament, tendon, cartilage, joint capsules, intervertebral discs
- tissues affected by lifespan, injury, pathology, physical activity, hydration, sex
- understanding biologic and mechanical nature of these tissues provides insights necessary for prevention and management of injuries to these structures-allows us to better balance stress and recovery in these tissues
CT and Musculoskeletal System
- a junction between two or more bones
- allow for varying degrees of motion: rotation, transfer and absorb force
- allow for varying degrees of segmental growth
Osteoarthritis and Joints
- cartilage becomes worn away, spurs grow out from edge of bone, and synovial fluid increases
- stiff and sore joints
- do right type of exercise to get the most amount of mileage out of joint
Synarthrosis
- held together by dense irregular connective tissue
- allows little or no motion
- functions: bind bones together, transmit force with little joint motion
- stability and force transmission decrease potential for injury
- types: sutures, gomphoses, and syndesmoses
Sutures
-2 bones grow together separated by only thin layers of fibrous periosteum
Gomphosis
-binds teeth to bony sockets separated by only thin layers of fibrous periosteum
Syndesmosis
- joint bound by ligament only
- most mobility of fibrous joints
Amphiarthrosis
- cartilaginous joints
- bones separated by hyaline or fibrocartilage
- functions: joint stability, minimal to moderate movement, shock absorption
- types: symphysis and synchrosis
Symphysis Joint
-segment of fibrocartilage joints bones
Synchondrosis
-hyaline cartilage joins bones
Diarthrosis
- aka synovial joint
- has fluid filled cavity which encapsulates the ends of the bones
- possess a joint space
- affords a large amount of motion: bone ends are not directly connected
Characteristics of Synovial Joints
- synovial fluid provides lubrication and nutrition to cartilage and other structures within joint
- hyaline cartilage covers ends of bones
- articular capsule
- vascular supply system supplies capsule but does not enter joint cavity
- receptors provide proprioception
- other elements include menisci, fat pads, labrum
Hinge Joint
- movement about single axis
- one degree of freedom
- ex: humeroulnar joint
- degrees of freedom mean how many motions are available at the joint
Pivot Joint
- one segment is ring shaped
- other is shaped so it can rotate within ring
- ex: humeroulnar joint
Ellipsoid Joint
- one segment has an elongated convex surface
- the other is an elongated concave surface
- ex: radiocarpal joint, ulnocarpal joint
Ball and Socket
- one segment has a spherical convex end
- other has concave surface
- ex: hip joint
Plane Joint
- bones are relatively flat allowing for gliding and some rotation
- ex: carpal joints, subtalar joint
Saddle Joint
- aka sellar joints
- each segment has both convex and concave portions
- ex: sternoclavicular joint
Condyloid Joint
- shallower version of ball and socket joint
- ex: atlanto-occipital joint
Synovial Joint Capsule
- functions to encapsulate joint
- produces and contains synovial fluid
- provides nutrition for articular cartilage
- layers of capsule: fibrous/stratum fibrosum, synovial membrane/stratum synovium which has 3 layers subsynovial tissue and intima,
- stratum synovium is not a true membrane and is poorly vascularized
- type A synoviocytes clear joint of waste materials
- type B synoviocytes provide viscosity to synovial fluid
- synovial membrane lines entire joint cavity except over surfaces of articular cartilage menisci-absorb as well as secrete
- outer fibrous capsule thickens in some areas to form ligaments
- synovia-covered fat pads prevent creation of joint vacuum
Synovial Joint Fluid
- viscous, pale, yellow, clear fluid
- component of plasma to which glycoproteins and hyaluronic acid have been added
- also present in synovial sheaths and bursae
- has no fibrinogen so does not clot
- functions: absorbs and transmits forces, nourishes articular cartilage, decreases friction between joint surfaces, provides a medium for diffusion of nutrients and waste between articular cartilage and synovial membrane
- principle components: water, proteoglycans, hyaluronic acid, lubricin
Embryonic Development of Synovial Joints
- articular disk of mesenchymal tissue appears at the future site of joint
- dense tissue surrounds the primitive joint plate and is forerunner of the joint capsule
- clefts or spaces are evident by 7th or 8th week of embryonic life filled with tissue fluid
- active intrauterine movement is crucial for joint health
Joints and Exercise
- short-term effects of clinical exercise: articular cartilage thickens (improved force dissipation), 2-3 times increase in volume of synovial fluid in a joint
- evidence supports endurance exercise’s benefits over strength training on ligament strength
- DJD (osteoarthritis): thinning articular cartilage, thickening compact bone under articular cartilage, possible genetic aging and environmental factors impact DJD development, regular runners do not have greater incidence of osteoarthritis
Articular Cartilage
- hyaline cartilage
- pearly white, partially translucent
- viscoelastic tissue: elastic solid, viscous liquid