bones are separated by fluid filled joint cavities and they are all diarthrotic (freely movable); they include almost all limb joints

bags of synovial fluid that act as lubricating "ball bearing" (not strictly a part of synovial joints, but they are closely associated)

Bursae: reduce friction where ligaments, muscles, skin, tendons, or bones rub together

Tendon sheaths: elongated bursae wrapped completely around tendons subjected to friction

Immobilization of bone by cast or traction is needed for healing; the time needed for repair depends on break severity, what bone is broken, and the age of the patient

Hematoma Formation: torn blood vessels hemorrhage, forming mass of clotted blood called a hematoma; site is swollen, painful, and inflamed

Fibrocartilaginous Callus Formation: capillaries grow into hematoma; phagocytic cells clear debris; fibroblasts secrete collagen fibers to span break and connect broken ends; fibroblasts, cartilage, and osteogenic cells begin reconstruction of bone; create cartilage matrix of repair tissue; osteoblasts form spongy bone within matrix; mass of repair tissue is called fibrocartilaginous callus

Bony Callus Formation: within one week, new trabeculae appear in fibrocartilaginous callus; callus is converted to bony (hard) callus of spongy bone; bony callus formation continues for about 2 months until firm union forms

Bone Remodeling: begins during bony callus formation and continues for several months; excess material on diaphysis exterior and within medullary cavity is removed; compact bone is laid down to reconstruct shaft walls; final structure resembles original structure; responds to same mechanical stressors

imbalances between bone deposit and bone resorption underlie nearly every disease that affects the human skeleton

Rickets are the osteomalacia of children; result in bowed legs and other bone deformities because bone ends are enlarged and abnormally long; the cause is vitamin D deficiency or insufficient dietary calcium

Osteoporosis: is a group of diseases in which bone resorption exceeds deposit; matrix remains normal but the bone mass declines; spongy bone of spine and neck of femur are most susceptible (making vertebral and hip fractures the most common; Risk factors are: aged or postmenopausal women, affects 30% of women aged 60-70 years and 70% by age 80, estrogen plays a role in bone density, so when levels drop at menopause, women run a higher risk; men are less prone due to protection by the effects of testosterone;infussifient exercise to stress bones, poor diet in calcium and protein, smoking, genetics, hormone related conditions, consumption of alcohol or certain medications; Treatments: calcium, vitamin D, supplements, weight bearing exercise, hormone replacement therapy, drugs; Preventing: calcium, reduction of alcohol and carbonated beverages, plenty of weight bearing excercise

Paget's Disease: excessive and haphazard bone deposit and resorption cause bone to grow fast and develop poorly; occurs in spine, pelvis, femur, and skull; rarely occurs before age 40; cause: unknown could be viral; Treatment: calcitonin an bisphosphonates

Osteoarthritis: protective cartilage at ends of Bones wears down; Causes: old age, bone deformities, more common in females; Symptoms: tenderness, pain, stiffness; Treatment: over the counter medication, physical therapy, cortisone injections

Osteogenesis Imperfecta: a genetic disorder that causes brittle bones; Causes: congenital mutation, frequent fractures, and bone bowing seen in fetal ultrasound; Symptoms: easily fractured bones, bluesdera, and muscle weakness; Treatment: uncurable, prescription medication to increase bone density, and improved nutrition

Osteosarcoma: malignant bone tumor; Causes: age, average age of diagnosis is 15 years, hereditary; Symptoms: bone Fracture, bone pain, and limited movement; Treatment: surgery, chemotherapy, radiation

Osteomyelitis: an infection in the bone; Causes: primarily staphylococcus, bacteria travels from the bloodstream into bone, from puncture infection; Symptoms: chills, fever, irritability; Treatment: antibiotics, surgical drainage, removal of diseased bone

Spongy Bone: appears poorly organized but is actually organized along lines of stress to help bone resist any stress

Trabeculae: like cables on suspension bridge confer strength to bone

No osteons are present, but trabeculae do contain irregularly arranged lamellae and osteocytes interconnected by canaliculi

Osteogenic: osteoprogenitor cells, mitotically active stem cells in the periosteum and endosteum, when stimulated they differentiate into osteoblasts or bone lining cells, some remain as osteogenic stem cells

Osteoblasts: bone forming cells that secrete unmineralized bone matrix (aka osteoid), osteoid is made up of collagen and calcium binding proteins, collagen makes up 90% of bone protein, osteoblasts are actively mitotic

Osteocytes: mature bone cells in lacunae that no longer divide, maintain bone matrix and act as stress or strain sensors, responds to mechanical stimuli like increased force on bone or weightlessness, communicate information to osteoblasts and osteoclasts so remodeling can occur

Bone-lining cells: flat cells on bone surfaces believed to also help maintain matrix with the osteocytes

Osteoclasts: derived from same hematopoietic stem cells that become macrophages, giant multinucleate cells function in bone resorption which is the break down of bone, when active cells are located in depressions called resorption bays, cells have ruffled borders that serve to increase surface area for enzyme degradation of bone, also helps to seal off area from surrounding matrix

Compact Bone: lamellar bone, made up of osteon, canals, and canaliculi, interstital and circumferential lamellae

Osteon (Haversian System: an osteon is the structural unit of compact bone, made up of elongated cylinder that runs parallel to long axis of bone, an osteon cylinder consists of collagen fibers that run in different directions in adjacent wings

Canals and Canaliculi: central canal runs through core of osteon, has blood vessels and nerves fibers, perforating canals are lined with endosteum that occur at right angles to central canal, connect blood vessels and nerves of periosteum, medullary cavity and central canal, connect blood vessels and nerves of periosteum, medullary cavity, and central canal

Canaliculi: hairlike canals that connect lacunae to each other and to central canal

Osteoblasts that secrete bone matrix maintain contact with each other and osteocytes via cell projections with gap junctions

Longer than they are wide; limb bones like arms and legs

Diaphysis: tubular shaft that forms long axis of bone; made up of compact bone surrounding central medullary cavity that is filled with yellow bone marrow

Epiphyses: ends of long bones that consist of compact bone externally and spongy bone internally; articular cartilage covers the articular joint surfaces

Between the diaphysis and the epiphyses there is an epiphyseal line; this is the remnant of the childhood epiphyseal plate where bone growth occurs

Periosteum: white, double-layered membrane that covers external surfaces except joints; Fibrous layer: outer layer consisting of dense irregular connective tissue consisting of sharpey's fibers that secure to bone matrix; Osteogenic layer: inner layer abutting bone and contains primitive osteogenic stem cells that gives rise to most all bone cells; contains many nerve fibers and blood vessels that continue on to the shaft through nutrient foramen openings; anchoring points for tendons and ligaments

Endosteum: delicate connective tissue membrane covering internal bone surface; covers trabeculae of spongy bone; lines canals that pass through compact bone; like periosteum contains osteogenic cells that can differentiate into other bone cells

Hematopoietic tissue in bones: red marrow is found within trabecular cavities of spongy bone and diploe of flat bones like the sternum; in new bones, medullary cavities and all spongy bone contain red marrow; in adults, red marrow is located in heads of femur and humerus, but most active areas of hematopoiesis are flat bone diploe and some irregular bones; yellow marrow can convert to red if person becomes anemic

Female pelvis is softer and wider while male pelvis is more narrow and harder

Female rib cage is more round and soft; has a greater lumbar curve