Bones Part 4 Joints

The Skeletal System Part 4JointsHonors Anatomy & PhysiologyJoints & HomeostasisJoints contribute to homeostasis by holding bones together in ways that allow movement & flexibilityJoints aka: articulation or arthrosisa point of contact between 2 bones, a bone & cartilage, or between a bone & tooth

Joint Classification1. structural classificationbased on anatomical characteristicsFibrous jointsCartilagenous jointsSynovial joints2. functional classificationbased on type of movement they permitSynarthrosisAmphiarthrosisDiarthrosis Fibrous JointsArticulating bones held very closely together by fibrous CT3 types:Suturesskull bonesSyndesmosesinterosseous membraneGomphoses dentoalveolar jointGomphoses

Cartilagenous Jointsallows little or no movementbones are tightly connected by either hyaline cartilage or fibrocartilage2 types:Synchondoseshyaline cartilage connects bonesepiphyseal plateSymphyses fibrocartilage connects bonepubic symphysisSymphyses

Synovial Jointsdistinguishing characteristics:synovial joint cavityfilled with synovial fluidbones covered by articular cartilagereduces friction Parts of a Synovial Joint

Synovial Fluidsecreted by synovial membraneviscous, clear, pale yellow fluidforms film over surfaces w/in articular capsulefunctions:reduce frictionabsorbing shockssupporting chondrocytes in w/in articular cartilageBy the way.cracking sounds heard as joints move or popping sounds people make when the crack their knuckles explanation:When synovial cavity expands creates partial vacuum suction from that draws CO2 & O2 out of blood vessels in synovial membrane form bubbles in synovial fluid bubbles pop

Sprains a forcible wrenching or twisting of a joint that stretches or tears ligaments but does not dislocate the bonesoccurs when ligaments are stressed beyond their capacitymay have associated damage to surrounding blood vessels, muscles, tendons, or nervesStrains stretched or partially torn muscleoften due to muscle contracting suddenly & powerfully

Bursae saclike structures situated to alleviate friction in some jointsfilled with fluid similar to synovial fluidlocated between: skin & bones tendons & bones muscles & bones ligaments & bonesBursae

Bursitis inflammation of a bursausually caused by irritation from repeated, excessive exertion of a jointor by: trauma, infection (syphilis or TB), RAsymptoms: pain, swelling, tenderness, limited movement

Types of Movements @ Synovial Joints1. Glidingrelatively flat surfaces move back-and-forth & side-to-side

Types of Movements @ Synovial Joints2. flexion/extension/ hyperextension:opposite movementsflexion: decrease in angle between articulating bonesextension: increase in angle between articulating boneshyperextension: continuation of extension beyond the anatomical position

Types of Movements @ Synovial Joints3. abduction/adduction/ circumductionabduction: movement of bone away from midlineadduction: movement of bone toward midlinecircumduction: movement of distal end of a body part in a circle

Types of Movements @ Synovial Joints4. elevation/depression:elevation: upward movement of part of body (closing mouth, shrugging shoulders)depression: downward movement of part of body (opening mouth, returning elevated shrugged shoulders to anatomical position)

Types of Movements @ Synovial Joints5. protraction/retractionprotraction: movement of part of body anteriorly in transverse planeretraction: returning a protracted part of body to anatomical position

Types of Movements @ Synovial Joints6. inversion/ eversioninversion: movement of soles medially @ intertarsal joints (soles face each other)eversion: movement of soles laterally @ intertarsal joints

Types of Movements @ Synovial Joints7. dorsiflexion/ plantar flexiondorsiflexion: bending foot @ ankle in direction of dorsum (superior surface)plantar flexion: bending foot @ ankle in direction of plantar surface

Types of Movements @ Synovial Joints8. supination/pronationsupination: movement of forearm in which palm is turned anteriorlypronation: movement of forearm in which distal end of radius crosses over distal end ulna & palm is turned posteriorly

Types of Movements @ Synovial Joints9. oppositionmovement of thumb in which thumb moves across palm to touch tips of the fingers on same hand

Identify Movements

Ball - & - Socket Jointball-like surface of one bone fits into a cuplike depression of another bonepermits movement around 3 axis + all directions in betweenflexionextensionabductionadductioncircumductionrotation

Homeostatic ImbalancesRheumatoid Arthritis (RA)autoimmune disease: immune system attacks joint liningscharacterized by: inflammation of joint swelling, pain, loss of functionusually bilateral joints involved but may not be to same degree

Medical Terminologyarthralgia: pain in a jointsubluxation: partial or incomplete dislocation of a joint