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JOINTS AND RELATED STRUCTURES • Articulations – points of contact b/w 2 bones. • Classified based on degree of movement Classification of joints: • Diarthroses – Freely movable joints (synovial joints) • Amphiarthroses – Joints that allow some motion (symphysis pubis) • Synarthroses – Immovable joints (skull sutures) Structural classification of joints • Fibrous – Consist of bones joined by short connective tissue fibers, most are synarthroses. • Cartilaginous – Consist of bones united by cartilage rather than fibrous connective tissue, most are amphiarthrotic • Synovial – Consist of a true joint cavity and consist of 2 bones whose articular ends are covered w/hyaline cartilage. Synovial joints • Structure – Joint cavity is lined by a synovial membrane, which secretes a watery fluid similar in composition to blood plasma w/o proteins. – Joint capsule is made of dense irregular CT and serves to provide strength and struc. reinforcement for the joint. – Synovial memb. lines the joint capsule. – Articular cartilage, hyaline cartilage. Provides a smooth, frictionless surface on which the bones slide. Synovial joints • Structure (Cont’d) – Ligaments connect bones to bones, to strengthen the joint. Some are w/I the joint cavity - extrinsic ligaments. Some are embedded in the capsule – intrinsic ligaments. – Articular discs – aka menisci, fibrocartilage pads improve the fit of two bones to prevent disolcation. Synovial joints • Surrounded by: – Tendon sheath, a sheath of connective tissue that surrounds the tendon, in which it can slide with a minimum of friction. – Bursa, a fluid-filled sac between the tendon and the joint, to lesson friction. TYPES OF MOTION • Flexion – Bringing 2 bones closer together, decreasing the angle b/w them • Extension – Act of increasing the angle b/w 2 bones, straightening motion • Abduction – Movement of extremity away from the body. Hyperextension increases the joint angle beyond the anatomic position. TYPES OF MOTION • Adduction – Movement of extremity toward the body • Circumduction – Includes, flexion, extension, abduction, adduction • Rotation – Bone moves around a central axis • Pronation – palm is downward/backward • Supination – palm is forward/upward. TYPES OF MOTION • Eversion – Moving foot away from the midline. • Inversion – Moving the foot toward the midline • Retraction – Moving the body backward on a plane parallel to the ground • Protraction – Moving the body forward on a plane parallel to the ground. TYPES OF MOTION • Elevation – Raising a part of the body • Depression – Lowering a part of the body • Oppostion – Tip of thumb and fingers are brought together • Reposition – When the digits to turn their normal positions • Dorsiflexion – Raising the foot up at the ankle joint • Plantar flexion – Pushing the foot down at the ankle. Types of joints: • Ball and socket – Multiaxial joint, ball-shaped head fits into a concave socket. – Exs. femur and acetabulum, humerus and scapula – Widest range of motion, all planes and directions. • Hinge joint – – – – Convex surface fits into a concave surface. Limited to flexion and extension. Uniaxial joints Exs. Knee, elbow, middle and distal phalanges Types of joints • Pivot joint – Uniaxial joint – Motion is limited to a single plane. – Pivot process rotates w/I a “hole” around a longitudinal axis. – Exs. Atlas and axis • Condyloid joint – – – – Biaxial joint Oval shaped protrusion that fits into an elliptical cavity Motion in at right planes of each other. Ex. Wrist, ankle Types of joints • Saddle joint – Biaxial joint – Movement is possible in two planes at right angles to each other, flexion and extension plus abduction and adduction. – Ex. Joint at phalangial and metacarpal/metatarsal end • Gliding joint – Multiaxial joint – Gliding motions – Ex. Superior and inferior articular processes of the vertebrae of the spine. Injury of bones and joints • Fracture – Restoring bone: • Closed reduction – manipulation , cast or splint. • Open reduction – surgical interventions, wires, metal plates, or screws. • Traction – pulling force, holds bones in place, long bones. – Types: • • • • Greenstick- simplest, partly bent, never separates Closed/simple –bone broken, not pierce t/skin. Open/compound-broken bones pierces t/skin Comminuted – bone is splintered Injury of bones and joints • Dislocation – When a bone is displaced from its proper position in a joint. – May result in tearing or stretching of the ligaments. – Reduction is necessary along w/rest to allow the ligaments to heal. • Sprain – Caused by a sudden or unusual motion. – Ligaments are usually torn – Treated w/ nonsteroidal anti-inflammatory drugs (NSAIDs). DISORDERS OF THE BONES AND JOINTS Making connections • Integumentary – S support for organs. – I provides vitamin D needed for Ca++ absorption and use • Muscular – S provided levers and Ca++ for muscle activity. – M pulls on bones, h bone strength and viability. Making connections • Nervous – S protects brain & spinal cord, depot for Ca++ ions. – N innervate bone and joint capsules for pain and joint sense. • Endocrine – S– protection, Ca++ stores. – E – hormones regulate uptake and release of Ca++, promote long bone growth and maturation. Making connections • Cardiovascular – S bone marrow site of blood cell formation, Ca++ stores for cardiac muscle activity. – C – delivers nutrients and O2 to bones, carries away wastes. • Lymphatic – S protection of lymphatic organs, bone marrow site of lymphocyte production. – L drains leaked tissue fluids, immune cells protect against pathogens. Making connections • Respiratory – S protects lungs – R provides O2, disposes of CO2 • Digestive – S protection of intestines, pelvic organs, and liver – D provides nutrients needed for bone health and growth Making connections • Urinary – S protects pelvic organs – U activates vitamin D, disposes of nitrogenous wastes. • Reproductive – S protects reproductive glands – R gonads produce hormones that influence form of skeleton and epiphyseal closure.