Clinical terms

1. Clinical terms • Dwarfism • Achondroplasia • Abnormal projection from a bone due to bony overgrowth • Bony spur • Pain in bone • Ostealgia • Bone inflammation • Osteitis • Inflammation of bone and bone marrow caused by pus-forming bacteria • Osteomyalitis • Bone cancer in a long bone of limb • Osteosarcoma • Fracture in diseased bone involving slight (coughing or quick turn) • Pathological fracture • Placing sustained tension on a body region to keep fractured bone in alignment • Traction

2. Epiphyseal Zones Resting cartilage • Name the 5 zones Proliferation Hypertrophy Erosion (Calcification) Diaphysis (ossification)

3. Resting Cartilage • Identify characteristics of this zone • Chondro’s resting in Lacunae • Not mitotically dividing • Not actively contributing to bone growth • Near epiphysis • Scattered chondro’s • What is the Role of this zone? • To anchor the rest of the epiphyseal plate to the epiphysis

4. Proliferation Zone • Identify characteristics • Chondro’s proliferating and dividing • Supplying new chondro’s to replace those lost to lengthening of bone • Proliferating cells stick up into narrow cells • Cells resemble stack of coins

5. Hypertrophy (Maturing) Zone • Identify characteristics • Cellular breakdown • Chondro’s begin to break down and produce alkaline phosphatase • Enzyme facilitates calcification of extra cellular matrix • Large chondro’s arranged in columns

6. Erosion Zone (calcification) • Identify • Calcium salts deposited in cartilage matrix by osteoids • Osteogenesis, osteoblasts laying down the matrix • Only a few cells thick • Dead cells because the matrix around them became calcified • Calcified matrix destroyed by osteoclasts (acids and enzymes), then invaded by osteoblasts and capillaries from diaphysis • Diaphyseal border of the plate firmly cemented to the bone of the diaphysis

7. Diaphysis Zone (ossification) • Identify • Long spiracles (tuberculae) that form spongy bone produced

8. Articulations - Appendicular • Clavicle: • Medially with sternum manubrium • Laterally acromium of scapula • Scapula: • Lateral with head of humerus at glenoid cavity • Humerus • Proximal with scapula • Distal with radius and ulna • Radius: (lateral thumb side) • Proximal with capitulum of humerus • Medial with radial notch of ulna • Distally, medial ulnar notch of radius to ulna and carpals • Ulna: (little finger side) • Proximal – trochlea of humerus • Distal – medial with radius at radioulnar joint

9. Osteological Terms - Processes • A rounded articulating process • Condyle • Any bony projection • Process • A projection located above a condyle • Epicondyle • A large rounded or irregular process • Tuberosity • A small rounded process • Tubercle • A very large, often blunt process • trochanter • A sharp, slender process • Spine • A hook-shaped process • Hamulus • A very slight ridge of bone • Line • A prominent ridge of bone • Crest • A smooth flattened articulating surface • Facet

10. Osteological terms - Fosae • A hole in a bone through which nerves and blood pass • Foramen • A tunnel-like passage through a bone • Meatus or canal • A cavity within a bone • Sinus • A furrow on a bone’s surface • Sulcus or Groove • A slit-like opening in a bone • Fissure • A shallow depression • Fovea

11. Identify parts of the bone • Tubular shaft of the long bone • Diaphysis • Part of long bone where growth occurs • Epiphysis • Irregularly arranged lamellae and osteocytes interconnected by canaliculi • Spongy bone (Cancellous, Trabeculae bone) • Marrow cavity in the shaft of long bone • Medullary cavity • Hematopoietic tissue found within trabecular cavities of spongy bone • Red marrow • Fat that fills cavities of bones • Yellow marrow • Membrane covering internal bone surfaces • Endosteum • Highly vascularized membrane covering the exterior of the diaphysis • Periosteum • Disc of hyaline cartilage that grows during childhood to lengthen the bone • Epiphyseal plate

12. Name functions of Skeleton System • Support • Bones support the body and organs • Protection • Protect vital organs: skull, sternum, vertebrae, ribs • Movement • Skeletal muscle contraction causes movement • Mineral storage • Calcium and other minerals stored in bone can be released into the bloodstream when needed (hormonal control) • Formation of blood cells • Hematopoiesis occurs in blood marrow resulting in the production of red and white blood cells and platelets

13. What are the 2 types of Osseous Tissue • Compact bone • Smooth, compact, with little air space • Haversian systems • Spongy bone (cancellous, trabecular) • Small pieces of bone surrounded by open spaces filled with red or yellow marrow

14. Name the 4 types of bone • Long bone • Shaft with a wide portion at both ends • Primarily compact bone with spongy at the widened areas • Humerus, radius, ulna, femur, tibia, fibula, phalanges • Short bones • Cube shaped, mostly cancellous bone • Wrist, ankle • Sesamoid – short bones embedded within tendon (patella) • Flat bone • Thin and flat • 2 layers of compact with spongy between • Sternum, ribs, skull • Irregular bone • Spongy with odd shape • Vertebrae and hip

15. Compact bone • Composed of? • Osteons or Haversion systems • Interspersed with? • Blood, lymphatic vessels and nerves • Concentric rings of compact bone called ____________ surround hollow passageways called ____________________ • Lamella, Haversion canals • What connects Haversion canals? • Volkman’s canals • Canals are lined with what tissue? • Endosteum • Where do osteocytes reside? • Lacunae • What connects the lacunae? • Canaliculi • What are the canaliculi’s function? • Permit nutrients and oxygen to pass between osteocytes • Remove wastes • What are interstitial lamellae? • Layers of bone that fill gaps between osteons • What are circumferential lamellae? • Large rings of bone extending around the entire shaft of the bone

16. Compact bone structure

17. Chemical Composition of bone • What are the organic components of bone? • Osteocytes, osteoblasts, osteoclasts • osteoid • What is the Osteoid comprised of? • Collagen fibers, proteoglycans, and glycoproteins • What is its function? • Flexibility and tensile strength on bone • What are the inorganic components? • Hydroxyapatites (mineral salts) which are mostly calcium phosphates (tiny crystals from the blood stream deposited among collagen fibers) • What are they responsible for? • Hardness of the bone • What are bone markings? • Bulges, depressions, rough spots, holes on the exterior surface of the bone • Most are muscle or ligament attachment sights

18. Name the 2 types of bone formation • Intramembranous ossification • Endochondrial Ossification

19. Intramembranous Ossification? • What is it? • The process of bone developing from a fibrous tissue • What bones are formed this way? • Flat bones such as the skull and clavicles • Explain the process: • Fibrous connective tissue in developing fetus become? • scattered with osteoblasts that begin secreting organic matrix. • Osteoid is? • then mineralized and osteoblasts become osteocytes • Osteoid accumulates in? • small networks of collagen fibers called trabeculae. • This early bone formation is called? • woven bone. • The periosteum forms around the? • woven bone. • Trabeculae thickens until they become? • plates of bone. • Eventually these plates of woven bone are replaced by? • compact bone. • Spongy bone remains in the center of the bone and the vascular tissue within it? • differentiates into red marrow (formation of diploe)

20. Intramembranous Ossification 1

21. Intramembranous 2

22. Intramembranous 3

23. Intramembranous 4

24. Endochondrial Ossification? • What is it? • The process of bone formation where hyaline cartilage is used as the model for constructing bone. Most bones are formed this way • Explain the process: • The perichondrium surrounding the hyaline cartilage bone model becomes infiltrated with? • blood vessels, converting it into periosteum. • Osteoblasts in the periosteum secrete? • osteoid externally onto the shaft of the hyaline bone • The matrix deep within the shaft of the cartilage begins to? • deteriorate • A periosteal bud containing arteries, veins, nerves and lymph vessels invades? • the internal cavity of the forming bone. • Osteoblasts from the periosteal bud begin to? • deposit osteoid, forming trabeculae of bone (early spongy bone) • Osteoclasts break down new spongy bone and open a? • medullary cavity in the center of the shaft • Secondary ossification centers form shortly before or after? • birth in the epiphyses of the bone. • Spongy bone is eventually formed with hyaline cartilage remaining only at the? • epiphyseal plate and the articular cartilages

25. Endochondral Ossification Secondary ossification center Articular cartilage Epiphyseal blood vessel Spongy bone Deteriorating cartilage matrix Hyaline cartilage Epiphyseal plate cartilage Spongy bone formation Primary ossification center Medullary cavity Bone collar Blood vessel of periosteal bud Formation of bone collar around hyaline cartilage model. Cavitation of the hyaline cartilage within the cartilage model. Formation of the medullary cavity as ossification continues; appearance of secondary ossification centers in the epiphyses in preparation for stage 5. Invasion of internal cavities by the periosteal bud and spongy bone formation. Ossification of the epiphyses; when completed, hyaline cartilage remains only in the epiphyseal plates and articular cartilages

26. Bone growth in long bones • How do long bones grow in children? • Entirely by interstitial growth of the epiphyseal plates • How do bones grow in thickness? • By appositional growth • The widening of bones

27. Epiphyseal bone growth • The top layer (epi side) of hyaline cartilage plate contains actively dividing chondrocytes that are pushed towards the ________________? • Diaphysis • What does this do? • Causes the entire bone to lengthen • What happens to the chondrocytes as they get closer to the shaft? • They enlarge and eventually die • What occurs at the junction of the epiphysis and the diaphysis? • Osteoblasts begin to secrete bone matrix and form small spicules of bone • What promotes the adolescent growth spurt and eventually leads to the closure of epiphyseal plate? • Sex hormones • What happens as adolescence ends? • The epiphyseal plate becomes smaller and is entirely replaced by bone tissue • What is the result of this occurring? • Bone growth ends

28. Long bone growth

29. Structure of long bone

30. What is appositional growth • The process used to? • Widen bones • _____________ beneath the _____________ form new ______________ systems on the outer surface of the bone • Osteoblasts, periosteum, Haversian • ________________ on the ________________ break down bone to enlarge the ______________ cavity. • Osteoclasts, endosteum, medullary

31. Appositional growth Periosteal ridge Central canal of osteon Penetrating canal Periosteum Artery Osteoblasts beneath the periosteum secrete bone matrix, forming ridges that follow the course of periosteal blood vessels. As the bony ridges enlarge and meet, the groove containing the blood vessel becomes a tunnel. 1 The periosteum lining the tunnel is transformed into an endosteum and the osteoblasts just deep to the tunnel endosteum secrete bone matrix, narrowing the canal. 2 As the osteoblasts beneath the endosteum form new lamellae, a new osteon is created. Meanwhile new circumferential lamellae are elaborated beneath the periosteum and the process is repeated, continuing to enlarge bone diameter. 3 4

32. Bone Remodeling • What is bone remodeling? • Process where bone is resorbed and deposited at periosteal or endosteal surfaces • What should the rate of bone resorption be in healthy adults? • The same rate as deposition so the total mass remains constant • What is bone deposit? • Osteoblasts laying down new osteoid which is later mineralized into bone • How is bone resorption carried out? • by osteoclasts secreting enzymes onto the bone that digest organic matrix. The osteoclasts also secrete acids that help to make the calcium salts more soluble • What is PTH? • Parathyroid hormone • Hormone produced by the parathyroid gland in response to low blood calcium levels. • It stimulates bone resorption so that calcium is released and put back into the blood • What is Calcitonin? • A protein produced by specialized “C” cells in the thyroid and secreted when blood calcium levels rise • Inhibits bone resorption and enhances calcium deposit in the bone matrix

33. Bone remodeling • How much of our bone mass is recycled every week? • 5 to 7% • How often is spongy bone replaced? Compact bone • Every 3 to 4 years • Every 10 years • What are remodeling units? • Packets of adjacent osteoblasts and osteoclasts that coordinate bone remodeling • What is bone deposit? • Added bone for injured or strength of bone • What is an osteoid seam? • The marking of new matrix deposits by osteocytes (band of gauzy looking bone matrix) • What helps trigger calcification? • Calcium and phosphate ions

34. Bone remodeling (cont) • What happens when calcium and phosphate mix reach a certain level? • Tiny crystals of hydroxyapatite form and catalyze further crystallization of calcium salts in the area • What are other factors involved? • Matrix proteins binding and concentrating calcium • Alkaline phosphatase mineralizing • When the conditions are met, what happens? • Calcium salts are deposited all at once and with great precision throughout the mature matrix

35. Bone resorption • What accomplishes this? • Osteoclasts • As they move along the bone surface what do they do? • Dig grooves called resorption bays and break down bony matrix • How does the area of bone destruction seal off? • By osteoclasts that touch the bone forming a ruffled membrane that clings to the bone, sealing it off • What does the ruffled border secrete and what does this do? • Lysosomal enzymes – digest organic matrix • Hydrocholoric acid – converts calcium salts into soluble forms in order to make them pass easily into solution • What happens to these products? • They are endocytosed and then released into the blood • What cells are important in this process? • T cells

36. Remodeling control • What regulates remodeling? • 2 control loops: • Negative feedback that maintains Ca2 Homeostasis in the blood • Gravitational forces acting on skeleton • Why is calcium so important for the body? • Nerve impulses • Muscle contractions • Blood coagulation • Gland and nerve cell secretions • Cell division • Where is 99% of calcium in the body? • Bone minerals • What range does the hormonal loop keep calcium? • 9-11 mg per 100 ml of blood • Where is calcium absorbed from? • Intestine

37. Hormonal Mechanism • What does the hormonal mechanism involve? • PTH – parathyroid hormone – parathyroid gland • Calcitonin – produced by parafollicular cells (C-cells) of thyroid gland • When is PTH released? • When calcium levels decline • What does it do? • Stimulates osteoclasts to resorb bone, release calcium into blood • What happens? • Osteoclasts break down old and new matrix • What escaped digestion and why? • Osteoid • Because it lacks calcium salts • When does the stimulus for PTH end? • When blood concentrations of calcium rise

38. Hormonal mechanisms (cont) • What is secreted when calcium levels rise? • Calcitonin • What is its function? • Inhibit resorption, encourage deposition • Reduce blood calcium • What happens when blood calcium levels fall? • Calcitonin release wanes • Are these responses to preserve bone strength? • No. They are for maintaining blood calcium homeostasis • What happens if levels are low for a long time? • Bones demineralize and develop large, punched out holes

39. Bone Remodeling

40. Mechanical Stress • What is Wolff’s law? • Bones grow and remodel in response to the demands placed on it? • What are other observations of Wolff’s law? • Long bones thickest midway along diaphysis (where stress is greatest) • Curved bones thickest where most likely to buckle • Trabeculae form trusses along lines of compression • Large bony projections occur where active heavy muscles attach • How do forces communicate with remodeling cells? • Electrical signaling • What are hormonal loops function in remodeling? • Whether and when remodeling occur • What are mechanical stresses functions? • Where remodeling will occur

41. Fracture Classification • Location of bone after fracture: • Non-displaced – normal end positions • Displaced – out of normal alignment • Completeness of break: • Complete – all the way through • Incomplete – not all the way • Orientation: • Linear – parallel of long axis • Transverse – perpendicular to axis • Skin penetration: • Open – penetrates the skin • Closed – skin not penetrated

42. Bone Repair • Hematoma formation: • Clotted blood forms at site • Bone cells die, tissue becomes inflamed • Fibrocartilaginous callus formation: • Capillaries grow into hematoma • Phagocytes begin cleaning debris • Fibros and osteos begin reconstructing bone • Fibros repair collagen, chondros repair cartilage • Osteos form spongy bone secrete bulging cartilage matrix that later calcifies • Fibrocartilaginous callus splints broken bone • Bony Callus formed: • Trabeculae appear in callus, convert it to bony callus • Bone remodeling: • Bony callus remodeled

43. Common Fractures • Comminuted: • Fragments into 3 or more pieces (aged, brittle boned) • Compression: • Crushed • Spiral: • Ragged break, excessive twisting (sports) • Epiphyseal: • Epiphysis separated from diaphysis • Depressed: • Broken inward • Greenstick: • Incomplete break on one side, other side bends

44. Clinical advances in bone repair • What does electrical stimulation do to a fracture? • Dramatically increases healing time • What is the piezo electric effect? • Minute electrical currents are produced when minerals are stressed • What happens in regions of negative electrical charge? Positive? • Negative – bone deposited • Positive – bone resorbed • What effect does ultrasound treatment produce on fractures? • Reduce healing times 35 to 45% • What is VEGF? Function? • Vascular endothelial growth factor • Stimulates blood vessel growth

45. Bone Imbalances - Osteoporosis • What is osteoporosis? • Group of diseases in which bone resorption occurs more than bone deposit • What are the results of the disease? • Reduced bone mass • Which bones are most susceptible? • Vertebrae, neck of the femur • Who is most likely to have this disease? • Postmenopausal women • Why? • Estrogen loss • What are some contributors? • Insufficient exercise • Poor calcium intake • Vitamin D or Calcitonin metabolism problems • Smoking, drinking • Immobility

46. Bone Imbalances - Osteomalacia • What is it? • Inadequate bone mineralization • Osteoid deposited but calcium salts are not • Weight bearing bones? • Fracture, bend, deform • What are Rickets? • Bowing of the legs and deformed pelvis • What causes this? • Insufficient calcium or vitamin D intake

47. Bone Imbalances – Paget’s Disease • What is Paget’s Disease? • Excessive, abnormal bone formation and resorption • What causes this? • High ratio of woven bone to compact bone and bone mineralization reduction • What is the result? • Soft, weak bones

48. Skeleton • What % of body mass is the skeleton? • 20% • How many bones? • 206 • What are ligaments? • Fibrous tissue that connect bones at joints

49. What are the 2 groups of skeleton? • Axial: • How many bones? • 80 • Which bones make up axial? • Skull, vertebrae, rib cage • Appendicular: • How many bones? • 126 • Which make up appendicular? • Upper, lower limbs, shoulders, hips

50. Skull • How many bones? • 22 including cranial and facial • What kind, how do they articulate? • Flat, sutures • What is the top, lateral and posterior of skull called? • The Calvaria • What are the 3 base regions? • Anterior, middle, posterior cranial fossae • What are the 4 pair of cavities called and what are they? • Paranasal sinuses - Sphenoid, Ethmoid, Maxillary, Frontal • Lighten the skull and give resonance to the voice • What is each cavity lined with? • Mucous membranes that form the mucus that drains into the nasal cavity • What are Orbits? • Eye cavities • Surrounded by fatty tissue • Formed by 7 bones