Intro To Bone And Soft Tissue Flashcards
What makes up the musculoskeletal system?
Bone
Muscle
Connective tissue - tendon, ligaments, cartilage
How many bones in adults and children?
Children 270
Adults 206
What are the Sri pets of the skeleton?
Appendicular: pectoral girdle, upper and lower limbs, pelvic girdle
Axial: cranium, vertebral column, rib cage
What are the functions of the skeleton?
- Support, helps to stand
- Protection of vital organs
- Movement, works with muscles to you can get around
- Mineral storage, calcium and phosphate
- Produces blood cells
How do bones develop in utero?
Flat bones: intermembranous mesenchymal cells —> bone
Long bones: endochondral mesenchymal —> cartilage —> bone
How does intramembranous ossification occur?
Mesenchymal to flat bones: skull, clavicle and mandible
- Condensation of mesenchymal cells which differentiate into osteoblasts - ossification centre forms
- Secreted osteoid traps osteoblasts which become osteocytes
- Trabecular matrix and periosteum form
- Compact bone develops superficial to cancellous bone. Crowded blood vessels condense into red bone marrow
How does endochondral ossification occur?
Development of long bones from a hyaline cartilage model
- Bone collar formation
- Cavitation
- Pereosteal bud invasion
- Diaphysis elongation
- Epiphyseal ossification
What are bones made up of?
Cells
Matrix
What are the bone cells?
Osteogenic cells - bone stem cells
Osteoblasts - bone forming, secrete osteoid, catalyse mineralisation of osteoid
Osteocyte - mature bone cells, forms when an osteoblast becomes embedded in its secretions, sense mechanical strain to direct osteoblast and osteoclast activity
Osteoclast - bone consuming, dissolve and resorb bone by phagocytosis, derived from bone marrow
Where are each of the bone cells found?
Osteogenic - deep layers of periosteum
Osteoblast - growing portions of bone including periosteum and endosteum
Osteocytes - entrapped in matrix
Osteoclasts- bone surfaces and at sites of old injuries or unneeded bone
What is the contents of the bone matrix?
Organic (40%) -
Type I collagen (90%) and ground substance (proteoglycans, glycoproteins, cytokines and growth factors) (10%)
Inorganic (60%) -
Calcium hydroxyapatite and osteocalcium phosphate
What are the types of bone?
Immature bone: first bone produced. Layed down in a woven manner, relatively weak. Mineralised and replaced by mature bone
Mature bone: mineralised woven structure. Lamellar (layer) structure, relatively strong
Types of mature bone:
Cortical (lamellar)- ‘compact’ dense. Suitable for weight bearing
Cancallous - ‘spongy’ honeycomb structure. Not suitable for weight bearing. Has trabeculae (spikes) that form lots of air spaces
What is an osteon?
The unit of bone found in compact bone. There are few spaces and it proves protection, support and resists stresses produced by weight of movement
Each osteon is made up of concentric lamellae around a central Haversian canal
Haversian canals contain blood vessels, nerves and lymphatics
Volkmans canals are transverse perforating canals that connect the Haversian canals
Lacunae are small spaces containing osteocytes
What is the structure of long bones?
Periosteum - connective tissue covering
Outer cortex - compact bone
Cancellous bone - in the middle
Medullary cavity - ossification centre, contains yellow bone marrow
Nutrient artery
Articular cartilage on surfaces at joints only
What are the plates at the end of bones?
Epiphysis - at very end
Physis- growth plate
Metaphysics
Diaphysis - long bit
How do bones grow?
Interstitial - long bones increasing in length
Appositional - increase in thickness and diameter
What is interstitial growth?
Long bone lengthening
Happens at the physis (physeal plate):
Zone of elongation of the bone
Contains hyaline cartilage
Epiphyseal side: hyaline cartilage active and dividing to form hyaline cartilage matrix
Diaphysis side: cartilage calcifies and dies, then replaced by bone
What is appositional growth?
Deposition of bone beneath the periosteum to increase thickness
- Ridges in periosteum create groove for periosteal blood vessel
- Periosteal ridges fuse forming an endosteum lined tunnel
- Osteoblasts in endosteum build new concentric lamellae inward towards centre of tunnel, forming a new osteon
- Bone grows outwards as osteoblasts in periosteum build new circumferential lamellae. Osteon formation repeats as new pereosteal ridges fold over blood vessel
What is the role of bone in calcium homeostasis?
Bone strores 99% of total body calcium - calcium hydroxyapatite- structural support
Calcium is deposited and withdrawn during bone remodelling
Regulated by PTH and calcitriol (vitamin D)
Calcitonin (parathyroid cells) stimulates calcium uptake into bone
How are joints classified?
Fibrous - sutures (skull), syndesmosis (tibia and fibia, radius and ulna) , interosseus membrane
Cartilaginous - synchondroses (spine), symphyses (pubic)
Synovial - plane, hinge, condyloid, pivot, saddle, ball and socket
What is the structure of a synovial joint?
Most common and most mobile joints
Joint capsule:
- articulate capsule (outer) - keeps bones together structurally
- synovial membrane (inner) - contains and secreted synovial fluid into synovial cavity (this reduces friction during movement)
How are synovial joints stabilised?
Bone surface congruity - well captured, very stable
Ligaments - made of collagen, stop bones moving in excess.
Muscles/tendons - help to stabilise joints
How do ligaments affect joint stability?
Prevent excessive movement that could damage joint
More ligaments and tighter ligaments: more stability but less mobility
Fewer or laxer ligaments: more mobility but less stability
Poor stability —> risk of dislocation
Disproportionate, in appropriate or repeated stress to ligaments -> Injury
Excessive ligament laxity -> hyper mobility-> risk of injury
What is a comparison of the hip vs shoulder?
Joint articulation: S(mismatch shallow socket) H(complete fit, deep socket)
Joint capsule: S(weak) H(strong)
Ligaments: S(lacks strong ligaments) H(strong network of ligaments)
Muscles: S(rotator cuff dependant) H(supported by muscles)
Stability: S(unstable) H(stable)
Mobility: S(extremely) H(less)
