Chapter 8 Joints - Dr. Stephens, Exam 2 PDF

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Dr. Stephens, Exam 2...

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Chapter 8: Joints  

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Joint articulation Functions o Depend on shape and composition  Mobility  Stability Classification o Structural  type of tissue at A.S.  Fibrous  Cartilaginous  Synovial o Functional  amount of movement  Synarthroses  Amphiarthroses  Diarthroses  Q: Where is each functional joint found in body?

Structural Classification 

Fibrous o Collagen fiber o Mostly synarthroses, some amphiarthroses o No joint cavity o Types:  Sutures (skull)  Long and short collagen fiber bundles  Permits very little movement (exception = fontanelles)  Ossified sutures = syntoses  Know how fontanelle develops  Syndesmoses  Bones connected by ligaments (bone to bone)  Length of band determines movement o Short = limited movement (tibia and fibula) o Long = greater degree of movement (radius and ulna allow supination)  Gomphoses  Only joint that does not join two bones together  Cementum of Tooth to bony alveolar socket  Periodontal ligament  joins maxilla and mandible to cementum of tooth  Short fibers = limited movement

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Cartilaginous o Hyaline cartilage joins bones o Synarthroses and amphiarthroses o Help prevent excessive movement o Types  Synchondroses  Bones united by plate of hyaline cartilage  Mostly synarthroses  Epiphyseal plate of growing long bones, costal cartilage  Symphyses  Fibrocartilage and hyaline cartilage on bone surface  Shocker absorbers  Limited movement  Intervertebral discs  herniate  Public symphysis Synovial Joints o Most complex & most joints o Location = appendicular skeleton  Diarthroses  Substantial movement allowed o 6 structures in all synovial joints  Auricular cartilage = hyaline cartilage on bone ends CUSHION  Joint cavity = space b/w articulating bones SPACE FOR SYNOVIAL FLUID  Articular capsule = encloses joint cavity….two layers  Outer = Fibrous layer o Strength and stability o Joins with periosteum  Inner = synovial membrane o Produce and secrete synovial fluid o Lines cavity except where hyaline cartilage is  Synovial Fluid = slippery fluid in joint capsule  Joint NOT active  viscous  Joint active  thin and watery  Reduces friction b/w articulating cartilages of articulating bones  Reinforcing Ligaments  Join articulating bones, provide stability  Types o Capsular o Extracapsular o Intracapsular  can stretch 6% of length, poor healing, more loose = strechier  Innervation and vascularization

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Innervation  sesory nerve fibers  prevent excess movement, monitoring (position stretch and pain) Vasculairzation  rich blood supply  capillary beds (synovial membrane) build synovial fluid

Structures Quasi-associated with synovial Joints  Burase o Flattened sacs that contain a small amount of synovial fluid o Found in places where bones, ligaments, muscles, tendons rub together o Reduce friction  Tedon (hotdog) muscle to bone o Tendon sheathe  Elongated bursa that wraps around tendon subject to friction  Location  crowded tendon areas (wrist/ankle)  Prevent excessive friction on particular tendon Joint Stability  Factors affecting joint stability o Articular surface  better bone fits together = more stable o Ligaments  more ligaments = stronger joint (kind of) o Muscle tone  slightly contracted muscles pull on tendon = brace bone Movement allowed by Synovial Joints  Nonaxial movement = gliding motion o Flat articular surfaces both bones o Plane joint in intercarpal and intertarsal joints, vertebra  Uniaxial Movement o One axis movement only o Flexion, extension, rotation  Hinge joint b/w humerus and ulna  Pivot joint b/w radius and ulna  Biaxial movement o Two axis of movement o Right angles to each other o Flexion, extension, adduction, abduction  Condylar joint (knuckle)  Saddle joint (thumb)  Multiaxial Movement o Multiple axes o Flexion/extension, abduction/adduction, rotation  Ball and socket joints (shoulder and hip)

Specific Synovial Joints 1. Temporomandibular joint a. Modified hinge b. Superior and inferior synovial cavity i. Superior  lateral excursion ii. Inferior  elevation/depression 2. Glenohumeral a. ball and socket b. most freely moving joint in body i. Reinforcing ligaments = loose (coracohumeral and glenohumeral ligament) ii. Rotator cuff = (sub, infra,supraspinatus and teres minor) encircle shoulder joint iii. Glenoid Labrum = rim of fibrocartilage around glenoid fossa  some stability 3. Elbow Joint a. Stability from close fit of trochlea (humerus) and trochlear notch (ulna) b. Articular capsule = thin, loose  flexion/extension i. Ulnar collateral ligament (medial) radial collateral ligament (lateral) prevent side-side movement ii. Muscle and tendons wrap around elbow  stability 4. Coxal Joint a. Deep socket & strong ligaments b. Acetabulum of os coxa has acetabular labrum to further deepen socket c. Ligaments of articular capsule: i. Iliofemoral ligament ii. Pubofemoral ligament iii. Ischiofemoral ligament d. Ligamentum teres: ligament of the head of the femur 5. Knee joint: a. single joint cavity shared by 3 separate joints b. 1) Femoropatellar joint (1): between patella and femur i. Plane joint c. 2) Tibiofemoral joint (2) : between femur and tibia i. Hinge joint allows flexion/extension d. Joint is only partially closed by joint capsule i. Anterior surface of knee has no capsule, is enclosed with ligaments e. Muscle and tendon reinforce joint with several ligaments i. Menisci- ridges lateral and medial ii. Extracapsular and capsular ligaments  prevent hyperextension iii. Intracapsular  secure articulating bones  prevent displacement

1. ACL prevent forward sliding of tibia and hyperextension a. Anterior 2. PCL prevent backwards sliding and forward sliding of femur a. Posterior Homeostatic Imbalances  Cartilage Tear o Cause: joint cartilage overstretched  snap and break  Compression/sheer tear simultaneous  After injury  joint less stable (locking)...