Topic 7.1 - Bone Structure (PDF)

🦴 Topic 7.1 - Bone Structure 2 large parts of the skeleton Axial + Appendicular Define “Axial” part of a Skeleton Axial: composed of all the bones of the skull, vertebral column (spine), ribs, and...

🦴 Topic 7.1 - Bone Structure 2 large parts of the skeleton Axial + Appendicular Define “Axial” part of a Skeleton Axial: composed of all the bones of the skull, vertebral column (spine), ribs, and sternum, which form the central line of the body. Define “Appendicular” part of the skeleton Axial part + bones of the limbs What causes the union between axial + appendicular Skeletons Topic 7.1 - Bone Structure 1  pectoral girdle + pelvic girdle Name one long bone (eg. Femur and Humerus) Topic 7.1 - Bone Structure 2  What is the role of a flat bone? generally used for protection or muscle attachment (i.e. Sternum or parietal) What is a short bone? small bones found in some joints (carpal bones in the wrist + tarsal bones in the ankles). What is a Sesamoid Bone? bones embedded within tendons or muscle → used to transfer force (eg. Patella). What is an irregular bone? Topic 7.1 - Bone Structure 3  bones which do not occupy any of the other categories (eg. Vertebrae). When does limb development begin during gestation + where do limb buds appear from? 4th week of gestation limb buds appear from the lateral plate mesoderm What is endochondral ossification converting a cartilage template —> long bone. Cartillage model forms three ossification centres (2 Epiphysial, 1 Diaphyseal) Explain the process of endochondral ossification 5 weeks - complete cartilage template for long bones. 8 weeks - Collar of bone starts forming around the middle of the bone 12 weeks - Primary ossification centre develops [Diaphyseal], causing Bone development. At birth: Topic 7.1 - Bone Structure 4  Secondary ossification centres form at the ends of the bone. During childhood: Epiphyseal growth plates develop. Secondary ossification centres develop into bone Adulthood: When full bone length is achieved, epiphyseal growth plates fuse. Ends of the bones remain capped with cartilage. What is intra-membranous ossification production of flat bone from stem cells without a cartilage template. contributes to the lengthening of long bones through growth at epiphyseal growth plates. What are the 4 descriptive regions of Bones Epiphysis - Ends of long bones, Develop from secondary ossification centres. Epiphyseal Plate - Growth site in length, Contains cartilage in actively growing bones. Metaphysis: Junction where the Diaphysis meets the epiphysis. Diaphysis:: Shaft of a long bone, Represents the primary ossification centre Topic 7.1 - Bone Structure 5  Name 3 types of Bone cells osteoblasts, osteocytes & osteoclasts What are osteoblasts? Cells Responsible for bone formation (makes osteocytes) Secrete collagen + other components for building mineralised bone matrix. What are Osteocytes? Mature bone cells from osteoblasts. Topic 7.1 - Bone Structure 6  Regulate osteoblasts and osteoclasts in response to mechanical signals. What are Osteoclasts? Large cells responsible for bone resorption (Break down/remove old bone tissue.) Essential for bone remodelling, repairing microdamage, and regulating calcium levels. What are the 2 types of osseous tissues Compact bone: Bony lamellae are strongly packed together with no space in between them → more dense and rigid Cancellous/Spongy/Trabecular bone: Irregular bone trabeculae are loosely distributed so that there is space (bone marrow) in between them. what are haversian systems (osteons) Haversian Systems (Osteons): Rings around a central canal with blood vessels + nerves for osteocytes. Strengthens bones, enhances resistance and durability Topic 7.1 - Bone Structure 7  2 forms of bone extracellular matrix Organic Substance: collagen → flexibility and strength to bone. glycoproteins and proteoglycans aid in organization and stress resistance. Inorganic Substance: Gives bone hardness and resistance to compression. Primarily hydroxyapatite crystals, a calcium phosphate compound. Explain “Bone Remodelling” Remodelling = process that involves the removal of old bone tissue (resorption) and the formation of new bone tissue. Osteoclasts - cells responsible for breaking down and removing old or damaged bone tissue osteoblasts - synthesizing and laying down new bone Explain the 4 stages of fracture repair Inflammatory Phase (Hematoma): Blood clotting + Inflammatory response begins. Topic 7.1 - Bone Structure 8  Specialized cells (immune cells and debris-cleaning cells) rush to the injury site. Soft/Fibrocartilaginous Callus Formation: Fibroblasts and Chondrocytes create a soft callus composed of cartilage and collagen —> Stabilizes the fracture site. Hard/Bony Callus Formation: Osteoblasts produce new bone tissue, replacing the cartilaginous callus —> Form a hard bony callus made of woven bone. Remodelling: Woven bone is remodelled —> Transforms into lamellar bone, which is stronger + more organized Define Joints and state the 3 types of joints Anatomy of a Synovial Joint Topic 7.1 - Bone Structure 9  Synovial Liquid – Highly Movable E.g., knee, shoulder main mean of union → articular capsule, a type of cuff that embrace the joint, attaching to both articulating bones Bones of the Upper Limb Topic 7.1 - Bone Structure 10  Bones of the Lower Limb Topic 7.1 - Bone Structure 11 Topic 7.1 - Bone Structure 12