Joints of the Skeletal System Classification Types of movements Synovial joints Joint disorders

Classification of Joints StructureStructure : (1) material binding bones (2) whether joint cavity is present –fibrous, cartilaginous & synovial joints FunctionFunction : amount of mov’t allowed at joint –synarthroses: immovable –amphiarthrosis: slightly movable/immovable –diarthroses: freely movable

Fibrous Joints Bones joined by dense CT, w/ no joint cavity & no movement: –suture :  b/t bones of the skull, interdigitate by overlapping, junction filled w/ CT, synarthrotic joints; infantile skulls are connected by membranous tissues  fontanels; adults  synostoses –syndesmosis :  bones bound by sheet or cord of CT (interosseous membrane), amphiarthrotic joint, e.g., tibiofibular joint vs. ulna & radius –gomphosis :  articulation of a tooth to a jawbone & held together via the peridontal ligament

Cartilaginous Joints Cartilage connects bones, lack joint cavity & slightly movable to immovable joints: –synchondrosis: band of hyaline cartilage joins bones, e.g., epiphyseal plate b/t diaphysis & epiphysis – amphiarthrotic joint; adult  synostoses –symphyses: articular surfaces of bone coved w/ hyaline cartilage - attached to fibrocartilage (shock absorber), e.g., pubic symphsis & IV discs – amphiarthrotic joints

Synovial Joints Articulating bones separated by fluid-containing joint cavity – diarthrotic joints 1. articular cartilage: 1. articular cartilage: hyaline cartilage covering 2. joint cavity 2. joint cavity: space  filled w/ fluid 3. synovial fluid 3. synovial fluid: contains GAGs & proteoglycans, phagocytic cells & nourishes cartilage 4. joint capsuleexternal layer internal layer 4. joint capsule: external layer -- tough flexible fibrous capsule continuous w/ periosteum; internal layer -- synovial membrane lining capsule 5. reinforcing ligaments 5. reinforcing ligaments: strengthen joint capsule & help bind articular ends of bones -- preventing excessive movement

Structure of a Synovial Joint #1 #4 #2 #3

Supporting Structures of Synovial Joints Menisci (articular discs)Menisci (articular discs): fibrocartilage b/t articular surfaces -- help cushion & increase stability BursaeBursae: fibrous sacs containing synovial fluid & act as ‘ball bearings’ preventing friction

Types of Synovial Joints

Six Types of Synovial Joints 1.Ball-and-socket joint: 1. Ball-and-socket joint: - bone w/ globular head - articulates w/ concave cavity of another bone, mov’t in all planes & rotational, e.g., hip & shoulder 2.Condyloid joint 2. Condyloid joint: - oval condyle of one bone fits into elliptical cavity of another bone, variety of mov’t in different planes, e.g., metacarpals & phalanges 3.Gliding joint 3. Gliding joint: - flat or slightly curved, allow sliding motion & twisting mov’t, e.g. wrist, ankle & vertebrae

Synovial Joints con’t. 4. Hinge joint: - convex surface of one bone fits into concave surface of another, permits mov’t in one plane, e.g., elbow & phalanges 5. Pivot joint: - conical surface of one bone protrudes into a ring formed of bones & ligaments, rotational mov’t occurs around a central axis, e.g., neck & head 6. Saddle joint: - bones having convex & concave surfaces, permit mov’t in 2 planes, e.g., carpal & metacarpal of the thumb

Synovial Joint Movements Flexion: joint angle decreases, e.g., bending knee Extension: joint angle increases, e.g., straightening knee Hyperextension: excessive extension, e.g., bending wrist back Dorsiflexion: flexion of ankle - foot approaches shin Planter flexion: extension of ankle - foot moves away from shin Abduction: mov’t of limb away from midline of body Adduction: mov’t of limb toward body midline

Types of Joint Movement con’t Rotation: moving a bone around a long axis Circumduction: moving a body part so that its end follows a circular path Supination: rotating palm to face anteriorly Pronation: rotating palm to face posteriorly Eversion: sole of foot faces laterally Inversion: sole of foot faces medially Protraction: forward mov’t in a transverse plane Retraction: backward mov’t in a transverse plane Elevation: lifting or moving superiorly along a frontal plane Depression: lowering elevated part to original position

1. The fetal position is an example of ___________? 2. Standing on ones toes is an example of ________ of the foot. 3. Bending the neck to observe the stars will cause ________ of the neck. 4. When one is standing erect most of the joints are in the _______ position. 5. Jumping jacks is an example of what primary movement of the arms and legs ________&_______? Review Questions

Common Joint Injuries Sprains: stretching or tearing CT assoc w/ the joint (spine, ankle & knee) Dislocations: bones are forced out of normal position in a joint cavity -- assoc w/ sprains (shoulders & fingers) Bursitis: inflammation of bursa due to overuse or stress (heal, knee & elbow) Tendonitis: inflammation of the tendon sheaths -- causes, symptoms & treatment mirror bursitis

Arthritis Rheumatoid arthritis (RA): –autoimmune disorder –inflammation & thickening of synovial membrane –cartilage is damaged & fibrous tissue infiltrates (small joints) –bones ossify (ankylosis) reducing movement w/ extreme pain –systemic illness -- anemia, osteoporosis, muscle atrophy & weakness & CVD Gout: –  [uric acid] deposited as urate crystals in soft tissue of joints (phalange of great toe) Lyme disease: –bacterial infection (deer tick)

Osteoarthritis (OA) –chronic degenerative disease occurs w/ aging (genetics) –affects articular cartilage -- exposed bone thickens forming bony spurs – stiffening joint & restricting mov’t –phalangeal, spine & weight- bearing joints most affected –risk factors: heredity, obesity, joint injury, overuse, age, sex,  phys. act.