2Connect 2 bones.Classified by structure or function
3Joint classification Classification by structure 1. Fibrous joints- bones held together by fibrous connective tissue2. Cartilagenous joints- bones held together by cartilage3. Synovial joints- complex structure with cartilage and cavitiesClassification by function1. SynarthrosesImmovable joints2. AmphiarthroseSlightly movable joints3. DiarthrosesFreely movable joints
4General background 1 extra joint category Bony joint (synostosis) Immobile (immovable)Fond when 2 bones ossify together (essentially merge or weld together)Some cranial sutures (fissures in the cranium) become ossifiedWhen the growth plate fuses/calcifies over (joining the epiphysis and diaphysis in long bones)
61. SuturesSuture: immobile joints in the skull (the fissures you see) through the thickness of the outer compact bone-“serrate” = wavy lines (like a serrated knife)- skull: parieta/frontal bones“lap”/ “squamous” = diagonal lineSkull: temporal/parietal bones“plane” / “butt” = straight linePaired maxillary and palatine bones
72. Gomphosis where teeth attach to bone Tooth is “held in place” by fibrous peridontal ligament” made of collagen that originates from the jaw boneFibrous “joint” permits slight movement when bitingAn important sensory mechanism that lets you know how hard or soft you are biting
8Gingivitis (gum disease) Bacterial infection destroys the ligament holding the teeth in placePromoted by the presence of plaque
9Scurvy A chronic lack of vitamin C leads to scurvy Vitamin C is necessary for collagen synthesisWith decreased collagen synthesis, joints are weakened, wounds do not heal well.How do you treat scurvy?
103. Syndesmosis Colllagen fibers bind 2 bones More mobility than suture or gomphosis, but still very limitedTibia – fibula at distal endRadius – ulna at distal ends
11Tibia/fibula Radius/ulna Note how far apart the radius/ulna are from one another compared to the tibia/fibula. This is one reason why your forearm is more “mobile” or flexible than your lower leg.
12Cartilaginous joints: (amphiarthrosis) Synchondoses: when bone is bound /joined by hyaline cartilageThe growth plate in long bonesThe first rib attaches to the sternum (ONLY the first rib)Symphyses: where bones are joined by fibrous cartilagePubic bone (pelvis)Between vertebrae
13Trick questionHow/why do infants and children have more joints than adults?
14Synovial joints - Very complex “synovial” joint because the joints are separated by a space (“synovial cavity”), where synovial fluid is retainedSynovial fluid rich in albumin (blood protein) and hyaluronic acid (a lubricant)
15Synovial joints Joint membrane: Outer fibrous capsule (continuous with the periosteum)Inner synovial membrane secretes the synovial fluid into the joint capsuleEach bone involved in the joint is covered by articular cartilage 2 mm thick-The bones making up the joint are “held together” by ligamentsHelp to locate the bones in the correct “place” so that their articular cartilage “rides” correctly
16Types of joints: classification by shape Ball & Socket joints (hip and shoulder)Hinge joints (ulna and femur…knee, fingers and toes)Pivot joints (radius and ulna…forearm/elbow and the first 2 vertebrae of your spine)Saddle joints (thumb, sternum/clavicle)Condyloid joints (fingers)
17Types of joints: classification by shape Ball & Socket joints (hip and shoulder)The ONLY multi-directional joints you have
18Types of joints: classification by shape Ball & Socket jointsHinge joints (ulna and femur…knee, fingers and toes)1 range of movement (flip-phone)
19Types of joints: classification by shape Ball & SocketHinge jointsPivot joints (radius and ulna…forearm/elbow and the first 2 vertebrae of your spine)When 1 bone spins on another, when you say no, or turn a door knob)
20Types of joints: classification by shape Ball & Socket jointsHinge jointsPivot jointsSaddle joints (thumb, sternum/clavicle)2 ranges of motion (hold something tight = sagittal plane, spread hand = frontal plane)Condyloid joints (fingers)2 ranges of motion: make a fist = sagittal plane, spread fingers = frontal plane
21Types of joints: classification by shape Ball & Socket jointsHinge jointsPivot jointsSaddle jointsCondyloid jointsGliding jointsBone surface almost flatBones slide along each otherEx: carpal bone, patella-femur
22Complex jointsMany joints have characteristics of multiple joint typesElbow is both a hinge joint (where ulna and humerus meet), as well as a pivot joint (where radius and ulna meet)Knee is similar to the elbow joint, without as much flexibility (much stronger and limited)Temporo-mandibular joint has both lateral and dorsal/ventral movement
23Complex synovial joints In a few joints (jaw = temporo-mandibular), (sternum/collarbone =sterno-clavicular), (ankle = distal tibia-fibula), there is an articular discIn your knee, this is called a meniscusfor guidance of the knee bonesfor shock absorption
24Accessories to synovial joints Other structures present in synovial joints:Tendons: collagen-based connective tissue that hold muscle to boneLigaments: collagen-based connective tissue that hold bone to boneBursa: fibrous “sac” that holds synovial fluidWraps around muscles prevent rubbing“bursitis” = inflammation of the bursa“tendon sheath”
26Movements of various joints Your shoulder (ball and socket) is a good example of a joint that is “multiarticulate”The ball and socket allows for:Abduction of the arm (flap your arms like a bird, jumping jacks)Flexion of the arm (extending to shake a hand or open a door)Rotation of the arm (sweeping your desk)
27Movements of various joints Abduction = raising arms above head (moving away from the anatomical position in the FRONTAL PLANE)Adduction = returning arms to side (returning to anatomical position in the FRONTAL PLANE)The terms abduction and adduction refer to the ACTION, NOT THE APPENDAGE that you are moving (you can also abduct and adduct your legs at the hip joint).
28Movements of various joints Elevation = lifting body part in the FRONTAL PLANE (moving away from the anatomical position)In this case, the model is raising their shoulders in the frontal or coronal planeDepression = returning to anatomical position from elevationThese terms refer to movement FROM the anatomical position, as well as back TO the anatomical position. These movement terms also refer to the PLANE of movement. In this case, we are dealing with the FRONTAL or CORONAL plane.
29Movements of various joints Protraction = moving body part forward (anterior movement) in a transverse or horizontal directionRetraction = posterior movement (“pushing out” his chest…he’s really pulling back his shoulders”)With these terms, there is reference to direction and plane of movement, however, this DOES NOT refer to the movement FROM or TO the anatomical position.
30Movements of various joints Flexion = decreasing joint angleIn this case, the models elbow is in flexionExtension = increasing joint angle to “zero position” (where it would “naturally rest)Hyperextension = moving beyond the zero positionNote that this movement DOES NOT refer to the plane of a joint, is only refers to the ANGLE of the joint.
31Movements of various joints Hyperextension = moving beyond the zero position
32Movements of various joints Circumduction = 1 end of the joint remains stationary, the other end makes a CIRCLE.Rotation = turning a joint longitudinallyon 1 bone of the joint
33Movements of various joints Supination =ONLY for FOREARM, when you turn your forearm so that the palms face forward or ventral (anatomical position)Pronation = ONLY for the forearm, when you turn your forearm so that the palm faces posterior or dorsal
34Movements of hand joints Radial flexion = tilting the hand towards the thumb (towards the radius)Ulnar flexion = tilting hand towards the pinky finger (towards the ulna)Abduction of the FINGERS is when you spread your fingers apartIn terms of your fingers:Flexion = curling fingers (like a fist)Extension = pointing your fingers
35Movements of hand joints Your THUMB is turned 90 from the rest of your fingers, so the previous “terms” for finger movement are DIFFERENT for your thumbAbduction = bring your thumb to your index finger (the “OK” sign)Opposition = touch pinky with thumbReposition = return to “zero” from the opposition positionIn terms of your THUMB:Flexion = bending towards the palm of your handExtension = pointing thumb up (hitch-hiking)Hyperextension = when you make a 90 angle between your thumb and index finger (straight up hitch hiker thumb)
36Movements of foot/ankle joints In terms of ANKLE movementsDorsiflection = lift toes up (standing on your heels)Zero position = feet flat on the ground, standing upPlantar flexion = pointing toes down (standing on your toes)In terms of your FEET:Your ankle can “roll” just like your wrist can “wave”Inversion = turning the plantar surface towards the median (standing on the outside of your feet)Eversion = turning the plantar surface laterally (standing on the arches of your feet)
37Complex joint: humero-scapular joint (shoulder) The scapula is connected to the thorax only by the clavicle (collar bone)Connection at the acromion process (look for a sharp hook)The joint between the clavicle and acromion = acromial-clavicular joint
38Humero-scapular joint Posterior viewAnterior viewNote how the ligaments and tendons wrap around the joint to hold the head of the humerus into the glenoid cavity. Also note how shallow the “socket” on the scapula is; an effort to increase mobility of this joint
39Loose ball and socket joint. More mobilityMuscles and ligaments stabilize the joint
40Complex joint: Elbow joint Actually 2 joints in 1 areaHumero-ulnar jointHumero-radial jointBoth enclosed by 1 single synovial joint capsule3rd joint in the elbow: radio-ulnar jointhead of the radius - radial notch in the ulnusimportant because it permits the forearm rotation (supine/prone) rotationYour tibia/fibula (shins) cannot rotate as well
41Features of the hand and wrist Also remember that your hand and wrist comprise a number of different joint types: saddle, gliding and condyloid. Together, these joints give your hands and fingers a great deal of and mobility