Intro to bone and soft tissue Flashcards
What is bone in muscoskeletal system for bone?
Joint
What is muscle in muscoskeletal system for bone?
Skeletal muscle (voluntary / straited)
What is connective tissue in muscoskeletal system for bone?
- Tendon
- Ligaments
- Cartilage
What are tendons?
Connects muscle to bone
What are ligaments?
Connects bone to bone
What is cartilage?
- Structural support
- Protect tissues
- Attachment sites
What is function of skeletal system?
- support
- movement
- Protection of vital organs
- Calcium storage
- Haematopoesis
How many bones are in the body?
206 Bones (+ sesamoids) [270 in children]
What is part of the appendicular?
pectoral girdle, Upper and Lower Limbs, Pelvic girdle
What is part of axial?
Cranium, Vertebral Column, Rib Cage
What are the different types of bone by shape?
- Flat bone
- Sutured bone
- Short bone
- Irregular bone
- Seasmoid bone
- Long bone
What is an osteogenic cell?
-Bone ‘stem cell
What is an osteocyte? How is it formed?
- ‘Mature’ bone cell
- Formed when an osteoblast becomes embedded in its secretions
- Sense mechanical strain to direct osteoclast and osteoblast activity
What is an osteoblast?
- Bone forming’
- Secretes ‘osteoid’
- Catalyse mineralisation of osteoid
What is an osteoclast?
- ‘Bone breaking’
- Dissolve and resorb bone by phagocytosis
- Derived from bone marrow
Where are osteocytes?
Embedded in matrix
Where are osteoclasts?
Bone surfaces and at sites of old, injured or unneeded bone
Where are osteogenic cells?
Deep layers of periosteum
Where are osteoblasts?
Growing portions of bone, including periosteum and endosteum
What are the two sections of bone matrix?
- Organic component (40%)
2. Inorganic component (60%)
What are the types of organic component in bone matrix?
- Type 1 collagen (90%)
2. Ground substance (10%) - proteoglycans, glycoproteins, cytokine and growth factors
What are types of inorganic component in bone matrix?
- Calcium hydroxyapatite
2. Osteocalcium phosphate
What is immature bone?
- First bone that is produced
- Laid down in a ‘woven’ manner – relatively weak
- Mineralised and replaced by mature bone
What is mature bone? What are the two types?
•Mineralised woven bone
•Lamellar (layer) structure – relatively strong
-Cortical
-Cancellous
What is cancellous bone?
- ‘Spongy’ – honeycomb structure
* Not suitable for weight-bearing
What is cortical bone?
- ‘Compact’ – dense
* Suitable for weight bearing
Describe cancellous bone
- Trabeculae (matrix of inorganic tissue
- Volume without weight
What is compact bone?
- Few spaces
* Provides protection, support and resists stresses produced by weight of movement
What are osteons?
Repeated structural units ‘Osteons’ – concentric ‘Lamellae’ around a central ‘Haversian Canal’
What is in the Haversian canal?
blood vessels, nerves and lymphatics.
What are the lacunae?
- small spaces containing osteocytes
- Tiny Canaliculi radiate from lacunae filled with extracellular fluid
What is Volkmans canal?
transverse perforating canals
How is compact bone organised?
- Parallel columns known as Haversian system, which run lengthwise down he axis of long bones
- These columns are composed of lamellae (concentric rings of bone) surrounding central channel (Haversian canal)
- Consists of closely packed osteons or Haversian systems
What is intramembranous ossification?
-During metal development
What are steps in endochondral ossification?
- Bone collar formation
- Cavitation
- Periosteal bud invasion
- Diaphysis elongation
- Epiphyseal
Where is the primary ossification centre?
Diaphysis
Where os the secondary ossification centre?
Epiphysis
What is endochondral ossification?
- Development of long bone from hyaline cartilage model
2. Takes longer than intramembranous ossification
What is interstitial growth?
Long bone lengthening
What is the epiphyseal plate?
- Zone of elongation in long bone
- Contains hyaline cartilage
- Epiphyseal side – hyaline cartilage active and dividing to form hyaline cartilage matrix
- Diaphyseal side – Cartilage calcifies and dies and then replaced by bone
What is appositional growth?
deposition of bone beneath the periosteum to increase thickness
Describe the process of appositional growth
- 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 toward center of tunnel, forming a new osteon
- Bone grows outwards as osteoblasts in periosteum build new circumferential lamellae. Osteon formation repeats as new periosteal ridges fold over blood vessel
What does vitamin D do?
Help absorb calcium D
What can happen in cancer?
Too much osteoclast activity so blood calcium high so depression renal stones
What is collagen?
- Most abundant protein in the human body.
- Crimping of fibres
- Non elastic behavior
- Fibre component of connective tissue
What is the structure of collagen?
- Molecule is a long, rigid structure
- Three polypeptides (referred to as α chains) are wound around one another
- Rope-like triple helix
Where is type 1 collagen?
Dermis, tendon, ligaments, and bone
Where is type 2 collagen?
Cartilage, vitreous body, nucleus pulpous
Where is type 3 collagen?
Skin, vessel wall, reticular fibre of most tissues (lungs liver spleen)
What does tendon do?
- Attaches skeletal muscle to bone
* Transmit muscle force to bone
What is the structure of tendon?
•Made of collagen fibres
•Stiff and Strong
-Collagen fibers arranged in bundles
What is the microstructure of tendon?
Parellel arrays of collagen fibres closely packed together
•Dry mass 30% of the total mass in water
•86% collagen, 2% elastin, 1-5% proteoglycans and 0.2% inorganic components eg. copper, manganese and calcium
What is the function of tendon?
- Transmit muscle forces
- Elastic energy storage / recoil
- PG resists compressive stresses
What do ligaments connect?
bone to bone to stabilise joint
What do ligaments enable?
proprioception
Describe ligaments
- Have functional subunits that tighten or loosen depending on joint position
- is not densely innervated or vascularised
What do ligaments contain?
- Contain some blood vessels and nerves in outer covering (epiligament)
- Contain proprioceptors
- Transmit pain signals via type C fibers
What does a normal ligament consist of?
- 90% Type 1 collagen (strong)
- 9% Type 3 collagen (immature; greater proportion in healing tissue)
- 1% fibroblast cells (the cells that produce collagen)
What does cartilage act as?
Acts as shock absorber to reduce friction
What does cartilage do?
Covers and protects long bones at joints
Structural component of ribs & IV discs Avascular and worn down in osteoarthritis
What is cartilage made up of?
Made up of chondrocytes – produce large amounts of collagenous ECM, ground substance
What are the 3 types of of cartilage?
- Elastic
- Hyaline
- Fibrocartilage
What are fibrous joints? (synarthrosis)
- Sutures
- Syndesmosis
- Interosseous membrane
- DO NOT MOVE
What are cartilaginous joints? (amphiarthrsosis)
- Synchondroses
- Symphyses
- Move a little
What are synovial joints? (diarthrosis)
- Plane
- Hinge
- Condyloid
- Pivot
- Saddle
- Ball and socket
-Move
Synovial fluid, shock absorption, lubricate
What are examples of synovial joints?
- Pivotal joint (e.g. between C1 and C2 vertebrae)
- Ball and socket joint (e.g. hip joint)
- Hinge joint (e.g. elbow)
- Condyloid joint (e.g. between radius and carpal bones of wrist
- Plane joint (e.g. between tarsal bones)
- Saddle joint (e.g. between trapezium carpal bone and 1st metacarpal bone)
What is a synovial joint?
Most common type of joint
Most mobile type of joint
What is in a synovial joint capsule?
- Articular capsule (Outer) – keeps bones together structurally
- Synovial membrane (Inner) - contains synovial fluid
What does synovial fluid do?
Reduces friction during movement
How are ligaments and joint stability related?
- Ligaments Prevent excessive movement that could damage joint
- More ligaments and tighter ligaments -> greater stability BUT less mobility
- Less ligaments and laxer ligaments -> greater mobility BUT less stability
What happens if there is poor stability?
Risk of dislocation
Disproportionate, inappropriate or repeated stress to ligaments -> injury (athletes are at risk of this)
What happens if there is excessive ligament laxity?
Hypermobility -> greater risk of injury
Muscular tone – eg. Rotator cuff
What are factors affecting joint stability?
- Joint shape e.g. hip vs shoulder
- Ligaments
- Tendons
- Cartilage (e.g. glenoid labrum)
What is the difference between the shoulder and hip stability with joint articulation?
Shoulder: mismatch shallow socket
Hip: complete fit deep socket
What is the difference between the shoulder and hip stability with joint capsule?
Shoulder: weak
Hip: strong
What is the difference between the shoulder and hip stability with ligaments?
Shoulder: lacks strong ligaments
Hip: strong network of ligaments
What is the difference between the shoulder and hip stability with muscles?
Shoulder: rotator cuff dependent
Hip: supported by muscles
What is the difference between the shoulder and hip stability with suability?
Shoulder: unstable
Hip: stable
What is the difference between the shoulder and hip stability with joint mobility?
Shoulder: extremely mobile
Hip: less mobile