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IUB ANAT-A 215 - Articulations

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2/2/15 ARTICULATIONS I. CLASSIFICATION OF JOINTSA. Articulations = joints: a place of union between two or more bonesB. Two ways to classify joints:1. Structurea. Fibrous Joints:i. dense regular CT connects bones ii. no fluid filled joint cavity b. Cartilaginous Joints:i. cartilage connects the bones ii. no joint cavityc. Synovial Joints:i. ligaments (dense regular C.T.) connect bones ii. contains a fluid-filled joint cavity 2. Movementa. Synarthroses: immovable joints b. Amphiarthroses:slightly moveable joints c. Diarthroses: freely moveable In joints, there’s an inverse relationship between mobility and stability (the more mobile a joint, the less stable it is)-more movement a joint has—the less stable it is II. FIBROUS JOINTS (all held together by dense regular CT)A. Suture: dense regular CT binds bones. –joints going in between skull bonesSynarthrotic joint (immoveable) Example: found connecting the flat bones of skull B. Syndesmosis: bones held together by interosseous ligament (sheet of dense regular CT) Amphiarthrotic joint (slightly moveable) Example: joint between radius and ulnaanother example: joint b/w tibia and fibula (sheet of tissue right between them) C. Gomphosis: root of tooth attached to jaw by dense regular C.T. (periodontal ligament). Synarthrotic joint (immoveable) III. CARTILAGINOUS JOINTSA. Symphysis: bones attached by pad of fibrocartilage. Amphiarthrotic joint (Slightly moveable) Example: pubic symphysis and intervertebral discs B. Synchondrosis: bones or bone segments connected by hyaline cartilage (hyaline cartilage=more rigid/firm) Synarthrosis (immoveable joint) Example: epiphyseal plate and costochondral joints no fluid between the bones IV. SYNOVIAL JOINTS: All are diarthrotic (freely moveable) A. Generalized structure1. ligaments (held together by ligaments)2. articular (joint) capsule a. fibrous capsule b. synovial membranei. makes synovial fluidii. LUBRICATION-REDUCES FRICTIONiii. ACTS AS SHOCK ABSORBER3. fluid-filled joint cavity4. Ends of bones lined w/ articular cartilage *hyaline cartilage reduces frictionB. Movements at Synovial joints.1. Flexion: decreases joint angle a. special kinds of flexion at ankle joint:i. dorsiflexsion: dorsum (top) of foot is pointed toward head (standing on heels)ii. plantar flexion: pointing foot away from head (“standing on the balls of your foot”) 2. Extension: increases joint angle b/w two bones 3. Abduction: body part moved away from midline of the bodyor extremetie/midline of body(fingers/toes moving away from eachother)4. Adduction: body part moved toward the midline of the body5. Rotation: movement of a body part around its own axisa. special kinds of rotation of forearm:i. supination: palm facing anteriorly (upward)—hint=see word up=supination ii. pronation: palm facing posteriorly (downward) 6. Circumduction: circular, conelike movement of a body segment 7. Inversion: movement of the sole of the foot inward or medially 8. Eversion: movement of the sole of the foot outward or laterally C. Kinds of Synovial Joints1. Hinge:a. permits bending in only one place b. allows for Flexion (decreases joint angle) and extension (increases joint angle) Example: knee and elbow joints 2. Pivot: a. permits rotational movement about a longitudinal axis Example: C1 (atlas) and C2 (axis) (used when shake head“NO”) 3. Gliding/Plane:a. Side-to-side movements Example: intercarpal joints another example: intertarsal joints (small or short bones with flat surfaces) 4. Condyloid (Ellipsoidal): (condyle=bone with rounded end)a. permits flexion, extension, abduction, adduction, and circumduction Example: knuckles (matacarpophalangeal; 4 MP joints) 5. Saddle: (shaped like saddle on a horse—sits right on top of bone) a. Permits flexion, extension, abduction, adduction, and circumduction Example: 1st metacarpocarpal joint (thumb) 6. Ball and Socket:a. provides greatest range of movementb. Permits flexion, extension, abduction, adduction, circumduction and rotation (turning on an axis) Example: hip & shoulder joints not a very stable joint because 6 movements All of the following are synovial joints EXCEPT:a. Suture****b. Glidingc. Pivotd. Ball and sockete.


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