Week 6- Intro to Bone & Soft Tissue Flashcards
What 3 components make up to musculoskeletal system?
Bone, muscle and connective tissue
What are the 3 types of connective tissue and what are their roles?
Tendon (connects muscle to bone)
Ligaments (connects bone to bone)
Cartilage (structural support, protects tissue, attachment sites)
How many bones are in the human skeleton for adults and children?
206 (270 in children)
What are the 2 types of skeleton?
Axial and appendicular
What does the appendicular skeleton contain?
Shoulder girdle, arm, hand, pelvic girdle, leg, foot
What does the axial skeleton contain?
Ossicles, skull, hyoid bone, thoracic cage, vertebral column
What are functions of the skeletal system?
Movement, support, protecting vital organs, calcium storage, haematopoeisis
What are the 6 bone shapes?
Flat, short, sesamoid, long, irregular, sutured
What are bone stem cells called?
Osteogenic cells
What are mature bone cells called?
Osteocytes
What do osteogenic cells produce? What is the function of these cells
Osteoblasts, they form bones
What is the function of osteoclasts?
Bone breaking- they dissolve and resorb bone vis phagocytosis
What are osteoclasts derived from?
Bone marrow
Where are osteocytes found?
Embedded in matrix
Where are osteoclasts found?
Bone surfaces and sites of old, injured or unneeded bone
Where are osteoblasts found?
Growing portions of bone, including periosteum and endosteum
Where are osteogenic cells found?
Deep layers of periosteum
What are the repeated structural units that bone is made up of?
Osteons
What 2 structures do osteons contain?
Concentric lamellae around a central haversian canal
What dies a haversian canal contain?
Blood vessels, nerves and lymphatics
What are lacunae?
Small spaces containing osteocytes
What are volkmans canals
Transverse perforating canals (smaller canals coming from the central canal)
What percentage of the bone matrix is organic and inorganic?
Organic: 40%
Inorganic: 60%
What does the organic component of the bone matrix contain?
90% type 1 collagen
10% ground substance (made of proteoglycans, glycoproteins, cytokine and growth factors)
What does the inorganic component of the bone matrix contain?
Calcium hydroxyapatite
Osteocalcium phosphate
What are the 2 types of way bone grows?
Woven or lamellar
What is woven bone?
Immature bone that is produced first, it is relatively weak and eventually mineralised and replaced by mature bone
What is lamellar bone?
Mature, minerlaised woven bone, relatively strong
What are the 2 types of mature bone?
Cortical and cancellous
Describe cortical bone
Compact and dense, suitable for weight bearing
Describe cancellous bone
Spongy bone w a honeycomb structure, not suitable for weight bearing
What are the 4 structures at the end of long bones (in order from topmost)
Epihysis
Physis
Metaphysis
Diaphysis
Describe the process of intra membranous ossification
Condensation of mesenchymal cells that 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
What is intramembranous ossification?
Formation of flat bones of skull, clavicle and mandible, bone development from fibrous membranes
Describe the process of endochondral ossification
Bone collar formation Cavitation Periosteal bud invasion Diaphysis elongation Epiphyseal ossification
What is endochondral ossification?
Development of long bone from a hyaline cartilage model
What has a shorter time frame out of endochondral and intramembrous ossification?
Endochondral ossification
What is the primary ossification center in endochondral ossification?
Diaphysis
What is the secondary ossification center in endochondral ossification
Epiphysis
What is interstitial growth? What key structure is involved with it
Long bone lengthening, involves the epiphyseal plate (the zone of elongation)
What is the epiphyseal plate?
The zone of elongation in long bone, it contains an epiphyseal side with hyaline cartilage thats active and dividing to form a matrix as well as a diaphyseal side where cartilage calcifies and dies and is replaced by bone
Define appositional growth
Deposition of bone under the periosteum to increase its thickness
Describe the appositional growth process
Ridges in periosteum create a groove for a blood vessel
Periosteal ridges fuse forming an endosteum lined tunnel
Osteoblasts in the endosteum build new concentric lamellae inward toward the center of the tunnel, forming a new osteon
Bone grows outwards as osteoblasts build new circumferential lamellae
What hormone effects bone during calcium homeostasis when plasma calcium levels are low?
PTH
How do bones help raise plasma calcium when its low?
Binding of PTH to receptors increases calcium mobilisation, helping raise plasma calcium
How do bones help reduce plasma calcium when calcium is too high?
Calcitonin is produced by the parathyroid cells, it binds to receptors in bone. This causes reduced osteoclast activity, helping reduce plasma calcium
What hormone effects bone during calcium homeostasis when plasma calcium levels are high?
Calcitonin
What is the role of tendon?
To attach skeletal muscle to bone
Describe the structure of tendon
Parallel arrays of collagen fibres closely packed together and arranged in bundles
Describe the functions of tendons
Transmit muscle forces to bone
Store elastic energy/recoil
Resist compressive stresses
Describe the structure of collagen
3 alpha chains wrapped around each other to form a triple helix
How many types of collagen are there and where are they found?
I- ligaments, tendons, skin, dermis
II- cartilage, vitreous body, nucleus pulposus
III- skin, vessel wall, reticular fibre of most tissues
What are the 2 main functions of ligament?
To join bone to bone to stabilise joints
To enable proprioception
How do ligaments work?
They have functional subunits that tighten and loosen depending on joint position
Describe the innervation/vascularisation of ligaments
They are not densely innervated or vascularised, they have a few nerves and blood vessels in the outer layer
What is the outer layer of a ligament called?
Epiligament
What type of receptor do ligaments contain?
Proprioreceptors
How do ligaments transmit pain signals?
Via type C fibers
What cells produce collagen?
Fibroblasts
What does ligament consist of?
90% type 1 collagen (strong)
9% type 3 collagen (immature- more prevalent in healing tissue)
1% fibroblast cells (cells that make ligament)
What are the 3 main roles of cartiledge?
To act as a shock absorber to reduce friction
Cover and protect long bones and joints
Structural component of ribs and IV discs
What is cartilage made of?
Chondrocytes- produce large amounts of collagenous ECM
What are the 3 types of ECM chondrocytes produce?
Hyaline
Elastic
Fibrocartilage
What is osteoarthritis?
The wearing down of cartilage
Describe the vascularity of cartilage
It is avascular
What mineral is released with osteoclast activity?
Calcium
What are the 3 types of joints?
Fibrous
Cartilaginous
Synovial
What are the 3 types of fibrous joints?
Sutures
Syndesmosis
Interosseous membrane
What are the 2 types of cartilaginous joints?
Synchondroses
Symphyses
What are the 6 types of synovial joints?
Plane Hinge Condyloid Pivot Saddle Ball and socket
What is the most common and mobile type of joint?
Synovial
What are the 2 components of a joint capsule in a synovial joint and what are their functions?
Articular capsule: outer part, keeps bones together structurally
Synovial membrane: contains synovial fluid
What is the function of synovial fluid?
To reduce friction during movement of the joint
What does poor joint stability lead to a risk of?
Dislocation
What does inappropriate stress to ligaments lead to?
Injury
What are the factors affecting joint stability?
Joint shape, ligaments, tendons, cartilage
What are some differential diagnosis for an old person who has recently had a fall and is experiencing pain where they fell? How would you investigate each one?
Fracture- do a radiograph
Torn muscle- look at soft tissue around the area of pain
Lumbar disc- ask if they’ve had nerve pain (shooting up the leg etc)
Hernia- when an organ protudes from the membrane thats supposed to contain it
Osteoarthirits- only possible if the pain has been chronic
What are important things to ask in a pediatric history?
Genetic history
History of the birth and pregnancy
Developmental milestones (were they normal)
Feeding and sleeping patterns
Behavior recently (any changes?)
Urinary and bowel movements (normal or changed?)
What are some common differentials for a limping child?
Rickets, stress fracture, transient synovitis of the hip
What are some life threatening differentials for a limping child?
Primary bone tumor, osteomyelitis, septic arthritis, haematological malignancy,
What is a joint aspiration?
When a sample of synovial fluid is taken from the joint by a needle to be tested
What are diagnostic criteria for septic arthritis of the hip?
Kocher Heart rate Temperature White cell count Can they out weight on the hip
What is the treatment for transient synovitis of the hip?
Prescribe non steroidal anti inflammatories
How may T2DM affect wounds?
People with T2DM often have poor wound healing, bone healing and soft tissue healing
How does bacteria in septic arthritis affect joint fluid?
Joint fluid will be turbid ie cloudy and pus like as well as straw coloured instead of clear
How are inflammatory markers affected in gout?
ESR- raised
CRP- raised
WBC- stays the same
