ARTICULATIONS!

Human Anatomy Unit 1 ARTICULATIONS Classifica3on of Joints •  Criteria –  How bones are joined together –  Degree of mobility •  Minimum components –  2 ar3cula3ng bones –  Intervening 3ssue •  Fibrous CT or car3lage •  Categories –  Synarthroses – no movement –  Amphiarthrosis – slight movement –  Diarthrosis – freely movable Synarthrosis •  Immovable ar3cula3on •  Types –  Sutures –  Schindylesis –  Gomphosis –  Synchondrosis Synarthrosis Sutures • 
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Found only in skull Immovable ar3cula3on Flat bones joined by thin layer of fibrous CT Types –  Serrate –  Squamous (lap) –  Plane Synarthrosis Sutures •  Serrate •  Serrated edges of bone interlock •  Two por3ons of frontal bones •  Squamous (lap) •  Overlapping beveled margins forms smooth line •  Temporal and parietal bones •  Plane •  Joint formed by straight, nonoverlapping edges •  Pala3ne process of maxillae Synarthrosis Schindylesis •  Immovable ar3cula3on •  Thin plate of bone into cleQ or fissure in a separa3on of the laminae in another bone •  Ar3cula3on of sphenoid bone and perpendicular plate of ethmoid bone with vomer Synarthrosis Gomphosis •  Immovable ar3cula3on •  Conical process into a socket •  Ar3cula3on of teeth with alveoli of maxillary bone •  Periodontal ligament = fibrous CT Synarthrosis Synchondrosis •  Car3lagenous joints –  Ribs joined to sternum by hyaline car3lage •  Synostoses –  When joint ossifies –  Epiphyseal plate becomes epiphyseal line Amphiarthrosis •  Slightly moveable ar3cula3on •  Ar3cula3ng bones connected in one of two ways: –  By broad flaYened fibro-­‐car3lage discs •  Fibrocar3lage •  Symphisis –  By interosseus ligaments •  Syndesmosis Amphiarthrosis Symphysis Amphiarthrosis Syndesmosis •  Two bones joined by interosseous membrane •  Example –  Radioulnar joint –  Tibulofibular joint Diarthrosis •  Synovial joints •  Freely movable •  Types –  Hinge –  Gliding –  Pivot –  Saddle –  Condyloid –  Ball and socket Synovial Joint Structure General Anatomy •  Ar3cular car3lage –  Hyaline car3lage –  Covers ends of bones •  Joint capsule –  Encloses joint cavity –  Retains synovial fluid –  Two parts •  Fibrous capsule •  Synovial membrane •  Synovial fluid – 
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Produced by fibroblasts Lubricates joint Nourishes ar3cular car3lage Removes waste Contains albumin and hyaluronic acid General Anatomy •  Meniscus –  Car3lages that do not cross joint –  Found in knee –  Shock absorbers –  Guide movement of bone –  Stabilize joint •  Accessory Structures –  Tendon –  Ligaments –  Bursae (pl.) •  Fibrous sac filled with synovial fluid Temperomandibular Joint •  Ar3cular disc –  Fibrocar3lage pad crosses joint capsule –  Found in temporomadibular and radioulnar joints Diarthroses Hinge Joints •  Monaxial •  Ar3cula3on between concave and convex surfaces •  Loca3ons –  Knee –  Elbow –  Between phalanges Diarthroses Gliding Joints •  Biaxial •  Ar3cular surfaces flat or slightly concave and convex •  Side to side or back/
forth mo3on with slight rota3on •  Loca3ons –  Between carpals –  Between tarsals Diarthroses Pivot Joints •  Monaxial •  Conical bone fits into a depression •  Rota3on around a central axis •  Loca3ons –  Radius/ulna –  Atlas/axis Diarthroses Saddle Joints •  Each ar3cular process is concave in one direc3on, convex in another •  A modified condyloid ar3cula3on with a wider range of movement •  Loca3ons –  Between the trapezium and 1st metacarpal –  Between the malleus and incus Diarthroses Condyloid Joints •  Biaxial •  Convex surface is oval shaped •  Up/down, side to side movements •  Loca3ons –  Radius/carpals –  Metacarpals/phalanges Diarthroses Ball and Socket Joints •  Mul3axial •  Greatest range of movement of all synovial joints •  Rounded convex surface with a cuplike cavity •  Loca3ons –  Shoulder –  Hip Movements of Synovial Joints • 
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Movement Terminology Flexion, Extension, and Hyperextension Abduc3on and adduc3on Eleva3on and depression Protrac3on and retrac3on Lateral and medial excursion Circumduc3on Rota3on Supina3on and prona3on Opposi3on and reposi3on Dorsiflexion and plantar flexion Inversion and eversion Flexion, Extension, and Hyperextension •  Flexion –  Decrease in the angle of the joint –  Usually in a sagiYal plane –  Ex) bending the elbow •  Extension –  Straightens joint and returns body part to anatomical posi3on –  Ex) straighten the elbow •  Hyperextension –  Extension of joint beyond 180o –  Ex) looking upward at the ceiling Abduc3on and Adduc3on, Eleva3on and Depression •  Abduc3on –  Movement away from the median plane –  Ex) Raising arm •  Adduc3on –  Movement toward the median plane –  Ex) Lowering arm •  Eleva3on –  Movement that raises bone ver3cally –  Ex) shrugging shoulders •  Depression –  Movement that lowers bone ver3cally –  Ex) lowering mandible to open mouth Protrac3on, Retrac3on, Lateral and Medial Excursion •  Protrac3on –  Movement of bone forward on a horizontal plane –  Ex) thrus3ng pelvis forward •  Retrac3on –  Movement of bone posteriorly •  Lateral and medial excursion –  Lateral: Sideways movement right or leQ –  Medial: Movement back to midline –  Ex) side to side grinding of teeth Circumduc3on and Rota3on, Supina3on and Prona3on •  Circumduc3on –  Movement conscribes a conical space –  Ex) winding up for a pitch •  Rota3on –  Bone turns on its longitudinal axis –  Ex) twis3ng at waist •  Supina3on (forearm only) –  Rota3on of forearm so that palm faces forward or upward •  Prona3on (forearm only) –  Rota3on of forearm so that palm faces toward rear or downward Opposi3on and Reposi3on, Dorsiflexion and Plantar Flexion •  Opposi3on –  Movement of thumb toward finger3ps •  Reposi3on –  Movement of thumb back to anatomical posi3on parallel to index finger •  Dorsiflexion –  Upward movement of foot •  Plantar flexion –  Stepping downward Inversion and Eversion •  Inversion –  Turning soles of feet inward medially toward each other •  Eversion –  Turing soles of feet outward away from each other Lever Systems •  Components 1.  Rigid rod: the sta3onary bone 2.  Effort •  applied force: supplied by muscle contrac3on 3.  Fulcrum •  pivot point: joint 4.  Resistance •  the load moved by the applied force •  the movable bone and anything aYached First Class Levers •  Fulcrum posi3oned between effort and resistance •  Joint works like a see-­‐
saw •  Example –  atlanto-­‐occipital joint (nodding) Second Class Levers •  Resistance posi3oned between the effort and fulcrum •  Joint works like a wheelbarrow or crowbar •  Example –  contrac3on of the calf muscles to elevate the body Third Class Levers •  Effort posi3oned between the fulcrum and resistance •  Most common •  Joint works like forceps •  Example –  elbow joint Range of Mo3on vs Power •  Range of mo3on and speed –  Variety of movements –  Number of movements per unit 3me •  Power (leverage) –  the amount of force •  Effort closer to the fulcrum (3rd class) –  increases range of mo3on and speed •  Resistance (load) closer to the fulcrum (2nd class) –  increases power