MT632 Skeletal System.docx

***Skeletal System*** --------------------- **Skeletal System** --------------------- **Cross-Section of the Human Bone** - Haversian system or osteon - Endosteum - Periosteum - Lamella -- bone matrix - Endosteal or inner circumferential - Haversian or concentric - Inter...

***Skeletal System*** --------------------- **Skeletal System** --------------------- **Cross-Section of the Human Bone** - Haversian system or osteon - Endosteum - Periosteum - Lamella -- bone matrix - Endosteal or inner circumferential - Haversian or concentric - Interstitial - Periosteal or outer circumferential A diagram of a bone Description automatically generated - Average adult has 206 bones **Subdivision** - Axial skeleton - Skull, auditory ossicles, hyoid, vertebral column, thoracic cage - Appendicular skeleton - Upper limb, lower limb - Girdles - Pectoral, pelvic  **Bone Shape Classifications** 1. **Long** - longer than they are wide; examples are upper and lower limb bones 2. **Short** - wide as they are long; examples are the bones of the wrist and ankle 3. **Flat** - Thin, flattened shape; examples are bones of the skull and sternum 4. **Irregular Bones** - Shapes that do not fit readily into the other three categories; examples are vertebra and facial bones -------------------------- **Skeletal terminology** --------------------------  1. Foramen: hole - Example - foramen magnum 2. Fossa: depression - Example - glenoid fossa 3. Process: projection - Example - mastoid process A diagram of the shoulder bone Description automatically generated  4. Condyle: smooth, rounded end - Example - occipital condyle 5. Meatus or canal: canal-like passageway - Example - external auditory meatus 6. Tubercle or tuberosity: lump of bone - Example - greater tubercle A skull with the bones of the skull Description automatically generated with medium confidence  -------------------- **Axial Skeleton** -------------------- - Skull -- 22 bones - Cranium - Encloses the cranial cavity - 8 cranial bones - Facial - 14 facial bones ------------------- **Cranial Bones** ------------------- 1. Frontal bone - Anterior part of cranium, the "forehead" 2. Parietal bones - Sides and roof of cranium 3. Occipital bones - Posterior portion and floor of cranium 4. Temporal bones - Inferior to parietal bones on each side of the cranium - Temporomandibular joint  5. Sphenoid bone - Forms part of cranium floor, lateral posterior portions of eye orbits, lateral portions of cranium anterior to temporal bones - Sella turcica 6. Ethmoid bone - Anterior portion of cranium, including medial surface of eye orbit and roof of nasal cavity - Nasal conchae A diagram of the skull Description automatically generated --------------------- **Cranial Sutures** --------------------- - Immovable joints called sutures **There are four principal sutures** 1. Coronal 2. Sagittal 3. Lambdoid 4. Squamous  -------------------- **Axial Skeleton** -------------------- - 13 facial bones are connected to form the bulk of the face - Mandible (total of 14 facial bones) - Freely movable joint - 3 auditory ossicles in each middle ear (six total) ------------------ **Facial Bones** ------------------ 1. Maxillae - Forms the upper jaw, anterior portion of hard palate, part of lateral walls of nasal cavity, floors of eye orbits - Maxillary sinus 2. Palatine bones - Form posterior portion of hard palate, lateral wall of nasal cavity 3. Zygomatic bones - Cheek bones - Also form floor and lateral wall of each eye orbit 4. Lacrimal bones - Medial surfaces of eye orbits 5. Nasal bones - Form bridge of nose  6. Vomer - In midline of nasal cavity - - Forms nasal septum with the ethmoid bone 7. Inferior nasal conchae - Attached to lateral walls of nasal cavity 8. Mandible - Lower jawbone - Only movable skull bone A skull with text and words Description automatically generated with medium confidence ----------------------- **Paranasal Sinuses** ----------------------- Several of the bones associated with the nasal cavity have large cavities within them, called the paranasal sinuses which open into the nasal cavity. The paranasal sinuses are: 1. Frontal 2. Ethmoid 3. Sphenoid 4. Maxillary A diagram of the human head Description automatically generated with medium confidence ---------------- **Hyoid Bone** ---------------- **Hyoid Bone** - Unpaired, U-shaped bone - Not part of the skull - No direct bony attachment to the skull or any other bones - Only bone in the body that does not articulate with another bone. - Attachment for some tongue muscles - Attachment point for important neck muscles that elevate the larynx  ---------------------- **Vertebral Column** ---------------------- **Vertebral Column** - Central axis of the skeleton, extending from the base of the skull to slightly past the end of the pelvis - 26 individual bones, grouped into five regions - Cervical - Thoracic - Lumbar - Sacral - Coccygeal - Four major curvatures: - Cervical, thoracic, lumbar and sacrococcygeal - 7 cervical vertebra - Atlas: 1st vertebra, holds head - Axis: 2nd vertebra, rotates head - 12 thoracic vertebra - 5 lumbar vertebra - 1 sacrum - 1 coccyx  **Functions of Vertebral Column** - Supports body weight - Protects the spinal cord - Allows spinal nerves to exit the spinal cord - Provides a site for muscle attachment - Provides movement of the head and trunk **Sacrum**  ------------------- **Thoracic Cage** ------------------- **Thoracic Cage** - Protects vital organs - 12 pair of ribs - Sternum: breastbone - True ribs: - attach directly to sternum by cartilage - False ribs: - attach indirectly to sternum by cartilage - Floating ribs: - not attached to sternum A diagram of the ribs and ribs Description automatically generated ------------------------------------ **Pectoral Girdle and Upper Limb** ------------------------------------ - Scapula: shoulder blade - Clavicle: collar bone  ---------------------- **Upper Limb Bones** ---------------------- 1. Humerus - upper portion of forelimb 2. Ulna - medial forearm 3. Radius - forearm 4. Carpals - wrist 5. Metacarpals - Hand 6. Phalanges - Fingers **Humerus**  **Ulna and Radius** A diagram of the bones of the lower limb Description automatically generated **Bones of the Wrist and Hand**  ------------------- **Pelvic Girdle** ------------------- **Pelvic Girdle** - Where lower limbs attach to the body 1. Pelvis - includes pelvic girdle and coccyx 2. Ischium - inferior and posterior region of hip bone 3. Ilium - most superior region of hip bone 4. Acetabulum - hip socket (joint) of hip bone **Hip Bones**  **\ ** **Comparison of the Male Pelvis to the Female Pelvis** A diagram of the pelvis Description automatically generated ---------------------- **Lower Limb Bones** ---------------------- 1. Femur - thigh 2. Patella - knee cap 3. Tibia - Larger bone of lower leg 4. Fibula - Smaller bone lower leg 5. Tarsals: - ankle 6. Metatarsals: - foot 7. Phalanges: - toes and fingers **Bones of the Thigh**  **Bones of the Leg** A diagram of bones and bones Description automatically generated MT632 LECTURE \| ANAPHY ***Skeletal System*** --------------------- **Skeletal System** --------------------- **Components of the Skeletal System** - **Bone** - **Cartilage** - **Tendons: attached muscle to the bone** - **Ligaments**  **Functions of the Skeletal System** 1. **Support. Bone is hard and rigid; cartilage is flexible yet strong. Cartilage in nose, external ear, thoracic cage and trachea. Ligaments -- bone to bone** 2. **Protection -- Skull around brain; ribs, sternum, vertebrae protect organs of thoracic cavity** 3. **Movement -- produced by muscles attached to bones via tendons. Ligaments allow some movement between bones but prevent excessive movement** 4. **Storage -- calcium and phosphate stored and released as needed. Adipose tissue stored in marrow cavities.** 5. **Blood cell production -- bone marrow that gives rise to blood cells and platelets** **2 Major Marrow Cavities** 1. **Red Bone Marrow** - **An active blood forming organ** - **Have stem cells which produce different types of red blood cells** 2. **Yellow Bone Marrow** - **Have the adipose tissue** - **Blood cell production** --------------- **Cartilage** --------------- **TYPES:** 1. Hyaline cartilage - Precursor of bones of the skeleton - Serve as binding elements for different types of joints especially for cartilaginous joints 2. Fibrocartilage - Serve as binding elements for different types of joints especially for cartilaginous joints 3. Elastic cartilage **CELL TYPES:** 1. Chondroblasts - form matrix - continuously synthesizing the materials of the matrix eventually these matrix accumulates and there is the chondroblasts 2. Chondrocytes - Matrix resurfaces; surrounded by matrix; are within lacunae (space like structure). **Cartilage Matrix** - Collagen fibers for strength, proteoglycans for resiliency. **Perichondrium** - Outer coverage/sheath - Dense irregular connective tissue that surrounds the cartilage - Does not cover all types of cartilages; can't be seen in fibrocartilage and articular cartilage - Double-layered C.T. sheath - Covers cartilage except at articulations. **Two layers of Perichondrium** - Inner - More delicate, has fewer fibers, contains chondroblasts. - Outer - Blood vessels and nerves penetrate (would distribute nutrients). No blood vessels in cartilage itself. - Invest of collagen fibers with fibroblast in between the fibers **Articular cartilage** ---------------------------------------- **Hyaline Cartilage - Chondrogenesis** ---------------------------------------- - Covers bones at joints; has no perichondrium Chondrogenesis - Development of cartilage **Cartilage Growth** - Appositional Growth - New chondrocytes and new matrix at the periphery - Found in the perichondral - Inner aspect -- we have the chondroblast actively secreting materials in the matrix - As the chondroblasts deposits the matrix, new matrix formed in the periphery which cause the expansion and growth of the cartilage tissue, thereby increasing the width of the tissue - Interstitial Growth - Happens in the middle of the cartilage - Longitudinal growth - Chondrocytes within the tissue divide and add more matrix between the cells - Actively dividing chondrocytes - Cartilage cells are actively engage in mitosis - Isogenous group or cell nest - Lacuna containing 2 or more chondrocytes A microscope view of a cell Description automatically generated -------------------- **Bone Histology** -------------------- **Bone matrix** - Organic - collagen and proteoglycans (ground substance within the matrix) - Inorganic - Hydroxyapatite or CaPO4 crystals *Must have a normal balance between organic and inorganic*  b\. If mineral removed, bone is too bendable c\. If collagen removed, bone is too brittle ---------------- **Bone Cells** ----------------  **Osteogenic Cells or Osteoprogenitor cells** - Stem cell population - Unspecialized bone stem cells -- originate from the mesenchyme (origin of the connective tissue) - Undergo cell division - When undergoes cell division or differentiate to form osteoblasts - Lines the inner portion of periosteum, endosteum, and bone canals **Osteoblasts** - Highly basophilic (an indication that these cells are actively dividing) - Bone building cells - Primarily role is to build materials **Osteoblasts produce bone matrix and become osteocytes** - Osteoblasts connect to one another through cell processes which we call as gap junctions and surround themselves with bone matrix to become osteocytes - Osteocytes are located in lacunae and are connected to one another through canaliculi (fluid filled canals; provides a medium where gases and nutrients diffuse then be delivers to the osteocytes for nourishment) - There will be small amount of bone matrix activity **Osteoblasts** - Bone building cells; involved in ossification or osteogenesis - Collagen is synthesized by E\>R pached in the golgi and released by exocytosis - They are precursors of hydroxypetite stored in vescileds, then released by exocytosis - Cells engaged in bone mineralization **Ossification** - Bone development - Function of osteoblasts cells - Process carried out by osteoblasts which though gap junctions - Cells surround themselves by matrix **Osteocytes** - Mature bon cells - Stellate shaped - Surrounded by matrix, but can make small amounts of matric to maintain it - Producing cytoplasmic extensions - Associated structures - Lacunae - Spaces occupied by osteocyte cell body - Canaliculi - Canals occupied by osteocyte cell processes - Nutrients diffuse through tiny amount of liquid surround cell and filling lacunae and canaliculi. They can transfer nutrients from one cell to the next through gap junctions ---------------------------------------- **Bone Cells -- osteoclast structure** ---------------------------------------- **Osteoclasts** - Separated from other 3 cause different origin; origin ng other 3 is (mesenchymal stem cells) - There are derived from the monocyte macrophage cell lineage - so these cells have phagocytic actions or activities - Resorption of bone. - Derived from monocytes (which are formed from stem cells in red bone marrow). - Multinucleated and probably arise from fusion of a number of cells. - Ruffled border: where cell membrane border bone and resorption is taking place. - H ions pumped across membrane, acid forms, eats away bone. - Create acidic environment -- bone matrix to be eaten up or eroded - Release enzymes (proteolytic) that digest the bone contributes to resorption process or bone erosion process **Stem Cells** - Mesenchyme (osteochondral progenitor cells) become chondroblasts or osteoblast A diagram of a cell Description automatically generated - Presence of folds: ruffled border - Site or the areas of the cell which resorption processes happens - Vesicles: has H ions and proteolytic enzymes   - As osteoclasts attached to the bone at areas which we call resorption areas, there is a space which separates the ruffled border to the bone itself (sealed zone or sealed compartment) ----------------------------------- **Classification of Bone Tissue** ----------------------------------- - According to the organization of collagen fibers **Two Different Types of Bones** 1. Woven bone - Primary or the immature bone - There are no definite pattern - Has collagen fibers oriented in random fashion. - Formed during fetal development and repair of fracture - It is remodeled (being replaced by new tissue or new matrix) to form lamellar bone 2. Lamellar bone - Mature bone - Arranged in thin layers / sheets called lamellae (how the matrix is being layers and how fibers are organized into sheaths) - Fibers are oriented in one direction in each layer but in different directions in different layers for strength A diagram of a bone structure Description automatically generated *Outer part made up of compact bone* *Trabeculae made up of spongy bone* *Spongy bone occupies a greater part of the epiphysis or the expanded ends of the bone, while Compact bone occupies the shaft or the longitudinal axis of the bone. Along the longitudinal axis we have the blood vessels and canals.* *Central canal = Haversian canal* *Lying perpendicular to the central canal = Volkmann's canal* 3. Spongy Bone (Cancellous Bone) - Trabeculae - Interconnecting rods or plates of bone - Like scaffolding - Spaces filled with marrow - Covered with endosteum - Oriented along stress lines - Important so the bone can withstand various stresses for whoch it can be exposed with  - Spaces will be filled up by bone marrows (red and yellow) 4. Compact Bone - Structure - Central or Haversian Canals: parallel to long axis - Lamellae: - 3 orientations: concentric (circular), circumferential, interstitial (in between concentric lamellae) - Osteon or Haversian system - central canal, contents, associated concentric lamellae and osteocytes - Blood vessel-filled central canal. - Concentric lamellae of bone surround central canal. - Lacunae and canaliculi contain osteocytes and fluid. - Circumferential lamellae on the periphery of a bone. - Interstitial lamellae between osteons. Remnants of osteons replaced through remodeling - - Perforating or Volkmann's canal - perpendicular to long axis. Both perforating and central canals contain blood vessels. Direct flow of nutrients from vessels through cell processes of osteoblasts and from one cell to the next. - Deliver blood to central canals - Run perpendicular to length of the bond - Nutrients and wastes travel to and from osteocytes via - Interstitial fluid of lacunae and canaliculi - From osteocyte to osteocyte by gap junctions A diagram of a bone structure Description automatically generated **Osteon**  - Canaliculi - Fine thread like structures radiating from the osteocytes and connecting it to adjacent osteocytes - Fluid filled canals **Perforating Canals** - Deliver blood to the central canal ------------------ **Bone Anatomy** ------------------ **Structure of a long bone.** 1. Diaphysis. - Shaft; primarily compact bone. - Long axis of bone 2. Epiphysis. - End of the bone; primarily spongy bone. 3. Epiphyseal plate - growth plate. - Hyaline cartilage; present until growth stops. **Metaphases** - Between diaphysis and epiphyses - Epiphyseal Line - Bone stops growing in length **Medullary cavity** - In children medullary cavity is red marrow - In adult, red marrow is replaced by yellow in limb bones (except for proximal epiphyses of arm and thigh bones) - Elsewhere, varying proportions of yellow/red marrow are found  4. Periosteum. - Covers the external surface of bone - Dense irregular connected tissue - Outer layer is fibrous - Inner layer (Osteogenic layer) is made up of single layer of bone cells including osteoblasts, osteoclasts and osteochondral progenitor cells. - Fibers of tendon become continuous with fibers of periosteum. - **Sharpey\'s fibers** - Bundles of collagen fibers - attaches periosteum to the bone proper - periosteal fibers that penetrate through the periosteum and into the bone. Strengthen attachment of tendon to bone. 5. Endosteum. - Similar to periosteum, but more cellular. - Lines all internal spaces including spaces in spongy bone. ------------------------------ **Young Bone Vs Adult Bone** ------------------------------ **Epiphyseal plate** - Is present in juvenile bone which is made up of hyaline cartilage while in adult long bone has epiphyseal line The shaft of long bones in infant and children have red bone marrow while in adult long bone it has yellow bone marrow, the red bone marrow only occurs in spongy bone of flat bones and some epiphyses. Biochemically speaking, the osteoid density of a child\'s bone is less than that of adult. Juvenile bones are also much porous than that of adult bone and this makes them more flexible.  Osteoid: unmineralized organic tissues of the bone which will later on ossification ---------------------- **Bone Development** ---------------------- **Ossification or Bone formation** - Initial formation takes place in an embryo and fetus - Growth of bones during infancy, childhood, and dolescnece until adult sizes are reached - **Two Methods of Ossification** 1. **Intramembranous Ossification** - Takes place in connective tissue membrane - Begins in areas called mesenchyme, starts from primitive connective tissue membrane or mesenchymal tissue or embryonic tissue 2. **Endochondral Ossification** - Takes place in cartilage - Begins with Hyaline cartilage **Both methods of Ossification** - Produce woven bone that is then remodeled - After remodeling, formation cannot be distinguished as one or other **Intramembranous Ossification** - Takes place in connective tissue membrane formed from embryonic mesenchyme - Forms many skull bones, part of mandible, diaphysis of clavicles. - When remodeled, indistinguishable from endochondral bone. **Centers of ossification:** - locations in membrane where ossification begins. **Fontanels:** - large membrane-covered spaces between developing skull bones; unossified. - Vernacular: bumbunan  In intramembranous ossification (process) a. formation of ossification center - initially start with the mesenchyme developing or forming osteogenic cells becoming an osteoblasts then form the matrix (yellow structure sa figure) - yung tissue surrounding it is called embryonic connective tissue - osteoblast are also engaged in producing precursor materials for calcium phosphate, that's why following the deposition o the matrix so there would be calcification - trabeculae: marks the formation of the spongy bone - areas of the skull, membrane covers spaces between the developing skulls (at birth remained unossified) **Endochondral Ossification** - responsible forms bones of the base of the skull, part of the mandible, epiphyses of the clavicle, upper and lower limbs, and most of remaining bones of skeletal system - developed long bones and short bones - cartilage formation begins at end of fourth week of development - some ossification beginning at about week 8; some does not begin until 18-20 years of age A diagram of bones and bones labeled Description automatically generated - perichondrium only on the lateral part cause yung side na wala will form articulation - Step 3: cartilage already died and replace by osteoblast Process 1. Formation of hyalin cartilage that acts as a model (begin at end the of 4^th^ week of fetal or embryonic development) ----------------- **Bone Growth** ----------------- - Growth in length occurs at the epiphyseal plate, organized into five zones. - Involves the formation of new cartilage by. - Interstitial cartilage growth (within the cartilage matrix, along longitudinal). - Appositional growth on the surface of the cartilage (start with inner layer of perichondrium, width). - Closure of epiphyseal plate: epiphyseal plate is ossified becoming the epiphyseal line. Between 12 and 25 years of age. - Articular cartilage: does not ossify, and persists through life. Growth at articular cartilage, increases size of bones with no epiphyses: For example, short bones. - Appositional growth only. - Interstitial growth cannot occur because matrix is solid. - Occurs on old bone and/or on cartilage - Occurs in the inner layer of the periosteum called osteogenic layer **Zones of the Epiphyseal Plate** 1. Zone of resting cartilage - Slowly dividing chondrocytes. 2. Zone of proliferation - New cartilage is produced on the. epiphyseal side of the plate as the chondrocytes divide and form stacks of cells. 3. Zone of hypertrophy - Chondrocytes mature and enlarge. 4. Zone of calcification - Matrix is calcified, and chondrocytes die. 5. Ossified bone - The cartilage on the diaphyseal side of the plate is replaced by bone.  -------------------------- **Bone Growth in Width** -------------------------- 1. Osteoblasts beneath the periosteum lay down bond (dark brown) to form grooves. Blood vessels of the periosteum lie in the grooves 2. The groove is transformed into a tunnel when the bone built on adjacent ridges meets. The periosteum of the groove becomes the endosteum of the tunnel 3. Appositional growth by osteoblasts from the endosteum results in the formation of a new concentric lamella 4. The production of additional concentric lamellae fills in the tunnel and completes the formation of the osteon.  - Beneath the periosteum = osteoblast - Ridges are separated by groove - As the groove in width progresses = groove changes into a tunnel happens as the adjacent ridges of the bones meet together - The periosteum of the groove becomes the endosteum of the tunnel - By the action of osteoblast coming from the endosteum, there would be deposition of matrix, then they are now layered forming a ring around the blood vessel ----------------------------------- **Factors Affecting Bone Growth** ----------------------------------- Size and shape of a bone determined genetically but can be modified and influenced by nutrition and hormones. - Nutrition - Lack of calcium, protein and other nutrients during growth and development can cause bones to be small. - Vitamin D - Necessary for absorption of calcium from intestines. - Absorption is also regulated by a hormone called parathyroid hormone - Can be eaten or manufactured in the body. - Rickets: lack of vitamin D during childhood. - Osteomalacia: lack of vitamin D during adulthood leading to softening of bones. - Vitamin C - Necessary for collagen synthesis by osteoblasts. - Collagen: strength; Comes with proteoglycans - Scurvy - deficiency of vitamin C - feeling of tiredness, severe joint pain - Lack of vitamin C also causes wounds not to heal, teeth to fall out - Hormones. - Growth hormone from anterior pituitary - Stimulates interstitial cartilage growth and appositional bone growth - Thyroid hormone - required for growth of all tissues - T3 or Triiodothyronine hormone produce by thyroid gland - Promote bone matrix remodeling (replacing the old matrix with new ones and regulates pathways which are involve in osteoblast proliferation - and differentiation) - Reproductive hormones - such as estrogen and testosterone. - Cause growth at puberty, but also cause closure of the epiphyseal plates and the cessation of growth - Acromegaly - Gigantism ---------------------------------- **Bone Remodeling -- Long Bone** ---------------------------------- Converts woven bone into lamellar bone. Caused by migration of basic multicellular units. - Groups of osteoclasts and osteoblasts that remodel bones. Involved in bone growth, changes in bone shape, adjustments in bone due to stress, bone repair, and Ca ion regulation. Relative thickness of bone changes as bone grows. Bone constantly removed by osteoclasts and new bone formed by epiphyseal plate osteoblasts. Formation of new osteons in compact bone. - Osteoclasts enter the osteon from blood in the central canal and internally remove lamellae. Osteoblasts replace bone. - Osteoclasts remove bone from the exterior and the bone is rebuilt. ----------------------------------------- **Mechanical Stress and Bone Strength** ----------------------------------------- Increased stress causes bone to increase in strength. This occurs by: 1. Remodeling. 2. Formation of additional bone. 3. Alter trabeculae to align with stress. Reduced stress results in more osteoclast activity as compared to osteoblast activity. --------------------------------------------- **Bone Fracture Classification and Repair** --------------------------------------------- Fracture classification based on: 1. Mechanism of fracture. - Traumatic, disease, pathologic 2. Soft-tissue damage. - Closed versus open 3. Displacement versus non-displacement 4. Fracture pattern. - Linear, spiral, avulsion, stress, compression 5. Number of fragments in the - Incomplete, complete, communited 6. Age-specific. - Greenstick and epiphyseal  - There's a trauma (motor accident) - Disease: Osteoporosis - Makes the bone brittle and easily break - Pathologic: Tumors **Classification of Fracture** 1. Close Fracture - Simple break on the skin - There is no soft tissue that is damage - Not even a skin is damage - Simple break on the bone 2. Open Fracture - Compound type of fracture wherein the bones are broken into fragments and protrudes through the skin - Displaced and moves out of alignment 3. Hair Line or Stress Fracture Patterns - There are tiny cracks on the bone - Usually occurs during accidents during sports or jumping or running activity 4. Spiral Fracture - Bone is broken in a twisting motion - Can be considered as complete fracture - Rabid breaks because of the twisting 5. Avulsion - Occurs when there's a small chunk of bone attached to a tendon or ligament got pulled away from a main part of the bone - Common site: hip, elbow, ankle fracture 6. Compression - Ex: Vertebra - Tends to collapse making it shorter - Tends to happen in the ventral vertebra causing one to stoop forward - Osteoporosis 7. Comminuated - The bone is broken in at least 2 places - Usually caused by a severe trauma (car accident) *When fractures are complete bones are broken into several pieces. When fractures are incomplete, there are cracks in the bone not totally breaking it into two or more pieces.* 8. Transverse - Bone is broken perpendicular to its length 9. Oblique - If the bone is broken at an angle (oblique angle) 10. Compression - Crash of the bone; happens usually when the bone is ferrous 11. Greenstick - The bone breaks incompletely - Only one side breaks and the other side bend - Depends on the age, commonly observed on children ----------------- **Bone Repair** ----------------- 1. Hematoma Formation - Localized mass of blood released from blood vessels but confined within an organ or space - Clot formation - Formation of hemorrhages - Increases as blood coming from the blood vessel ooze out - Bleeding cause from the trauma 2. Callus formation - Callus - - Mass of tissue that forms at a fracture site and connects the broken ends of the bone - Can happen internally and externally - Internal -- blood vessels grow into clot in hematoma - Macrophages clean up debris, osteoclasts break down dead tissue, fibroblasts produce collagen and granulation tissue - Chondroblasts from osteochondral progenitor cells of periosteum and endosteum produce cartilage within the collage - Osteoblasts invade. New bone is formed - External -- collar around opposing ends - Periosteal osteochondral progenitor cells -\> osteoblasts and chondroblasts. Bone/cartilage collar stabilizes two pieces  3. Callus ossification - Callus replaced by woven, spongy bone 4. Bone remodeling - Replacement of spongy bone and damaged material by compact bone. - Sculpting of site by osteoclasts ------------------------- **Calcium Homeostasis** ------------------------- Bone - Major storage site of calcium - The level of calcium in the blood depends upon movement of calcium into or out of bone - Calcium enters bone when osteoblasts create new bone; calcium leave bone when osteoclasts break down bone **Three hormone control blood calcium levels:** 1. Parathyroid hormone (PTH) - Secreted by cells in parathyroid gland. - Reduction in blood calcium is stimulus for release of PTH. **Direct effects of PTH** a. Activates osteoclasts, increases number of osteoclasts, and prevents inhibition of osteoclast formation. - With more osteoclast activity (responsible of the erosion of the bone), bone is resorbed and calcium released into blood b. Stimulates reabsorption of calcium from urine in the kidney tubules. **Indirect effects of PTH** - Promotes activation of calcitriol, a hormone that increases calcium absorption in the small 2. Calcitriol - Increases blood calcium by stimulation intestinal absorption of calcium - Derived from Vitamin D3 3. Calcitonin - Lowers blood calcium by inhibiting osteoclast activity - Negative feedback manner A diagram of blood calcium level Description automatically generated With low level of calcium: - Parathyroid hormone will be secreted and two substance, parathyroid hormone and calcitriol, will stimulate the formation of the osteoblasts - PTH will increase the reabsorption of the calcium ion in the kidney tubules - Calcitriol stimulate the calcium uptake in the small intestine ------------------------------------- **Diseases of the Skeletal System** ------------------------------------- **Abnormal Spinal Curvatures** 1. Scoliosis (twisted disease) - Abnormal rotation of the spine resulting in a lateral curvature 2. Kyphosis (hunchback) - Dorsally exaggerated thoracic curvature 3. Lordosis (swayback) - Accentuated lumbar curvature - Temporary: \"potbellies\" and pregnant women  **Bone Disorders** 1. Rickets - Disease in children; epiphyseal plate cannot calcify 2. Osteomalacia (\"soft bones\") - Bone are poorly mineralized - Osteoid is produced but calcium salts are not adequately deposited 3. Osteomyelitis - Osteomyelitis is a bone infection. - Fungi or bacteria - Painful swelling in the bone marrow - If left untreated -- it can cut off blood supply, following the death of the bone 4. Osteoporosis - Osteoporosis is a severe lack of bone density. - Group of disease in which bone resorption outpaces bone deposit - Matrix composition is normal but bone mass declines - Women are more susceptible than men - Treatment - Vit D and calcium supplement - Exercising - Hormone replacement ------------------------------------------------- **Diagnostic Test Used for Skeletal Disorders** ------------------------------------------------- 1. Calcium 2. Alkaline phosphatase - Very important bone enzyme 3. C-telopeptide (C-terminal telopeptide of type 1 collagen (CTx)) - a marker for bone resorption. It is used to monitor anti-resorptive therapies, such as bisphosphonates and hormone replacement therapy, in postmenopausal women and people with low bone mass (osteopenia) 4. P1NP (Procollagen type 1 N-terminal propeptide) - a marker for bone formation.It is the most sensitive marker of bone formation and particularly useful for monitoring bone formation therapies and anti-resorptive therapies 5. Magnetic Resonance Imaging (MRI) Scans - MRI scans are often the best test for outlining a bone tumor - They are very helpful for looking at the brain and spinal cord - Tendon, cartilage, bones are visualized - Mas ginagamit for bones kasi mas nakikita 6. Computed Tomography (CT) Scans - Helpful in staging cance - It can also be used to guide a biopsy needle into a tumor - This is called a CT-guided needle biopsy  7. DEXA (dual-energy X-ray absorptiometry) scan - The use of low-dose radiation to measure bone density in the hip and vertebrae 8. X-ray - The use of electromagnetic radiation that send photons through the bod y to create a visual image of dense structures such as bone 9. Surgical Needle Biopsy - In the procedure, a surgeon needs to cut through the skin to reach the tumor to remove a small piece of tissue - This is also called an incisional biopsy - If the entire tumor is remove (not just a small piece), it's called an excisional biopsy A close-up of a syringe Description automatically generated ----------------------------------------- **Effects of Aging on Skeletal System** ----------------------------------------- - Bone matrix decreases. More brittle due to lack of collagen; but also less hydroxyapatite - Bone mass decreases. Highest around 30. Men denser due to testosterone and greater wight. Africa Americans and Hispanics have higher bone masses than Caucasians and Asians. Rate of bone loss increases 10 fold after menopause. - Spongy bone lost first, then compact - Increased bone fractures - Bone loss causes deformity, loss of height, pain, stiffness - Stooped posture - Loss of teeth