Introduction to Bone and Soft tissue Flashcards
What does the musculoskeletal system consist of?
Bone
Muscle
Connective tissue
What are the different types of connective tissue?
Tendon
Ligaments
Cartilage
What is the function of cartilage?
Structural support
Protect tissues
Attachment sites
How many bones in the human skeleton?
206
270 in children
What are the appendicular parts of the skeleton?
Pectoral girdle
Upper and lower limbs
Pelvic girdle
What are the axial parts of the skeleton?
Cranium
Vertebral Column
Rib cage
What are the functions of the skeletal system?
Movement Support Protection of vital organs Calcium storage Haematopoesis
What are the different types of bones?
Flat bone Sutured bone Short bone Irregular bone Sesamoid bone Long bone
What is an osteogenic cell?
Bone ‘stem cell’
What is an osteocyte?
‘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 do you find osteocytes?
Embedded in matrix
Where do you find osteoclasts?
Bone surfaces and at sites of old, injured or unneeded bone
Where do you find osteogenic cells?
Deep layers of periosteum
Where do you find osteoblasts?
Growing portions of bone, including periosteum and endost
What is a osteon?
Repeated structural unit
Where you find the 4 types of bone cells
What composes the bone matrix?
Organic: Collagen and ground substance
Inorganic: Calcium hydroxyapatite
and osteocalcium phosphate
What is ground substance made of?
Proteoglycans
Glycoproteins
Cytokine and Growth factors
What are the main features of immature bones?
First bone that is produced
Laid down in a ‘woven’ manner – relatively weak
Mineralised and replaced by mature bone
What are the main features of mature bone?
Mineralised woven bone
Lamellar (layer) structure – relatively strong
What are the two types mature bone?
Cortical
Cancellous
What are the main features of cortical bone?
‘Compact’ – dense
Suitable for weight bearing
What are the main features of cancellous bone?
‘Spongy’ – honeycomb structure
Not suitable for weight-bearing
What is the growth plate called?
Physis
What is intramembraneous
ossification?
Forms flat bones of skull, clavicle and mandible
Bone development from fibrous membranes
Mesenchymal cell template
How does intramembranous ossification occur?
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
What is endochondral ossification?
Development of long bone from a hyaline cartilage model
Takes longer than intramembranous ossification
Primary ossification center - diaphysis
Secondary ossification center – epiphysis
What are the steps of endochondral ossification?
Bone collar formation Cavitation Periosteal bud invasion Diaphysis elongation Epiphyseal 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
How does appositional growth occur?
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 are the main features of collagen?
Most abundant protein in the human body.
Molecule is a long, rigid structure
Three polypeptides (referred to as α chains) are wound around one another
Rope-like triple helix
Crimping of fibres
Non elastic behavior
Fibre component of connective tissue
What is collagen made up of?
Amino acid
Collagen molecules
Collagen fibrils
Collagen fibrils
Where is type I collagen?
Dermis, tendon, ligaments and bone
Where is type II collagen?
Cartilage, vitreous body, nucleus pulposus
Where is type III collagen?
Skin, vessel wall, reticular fibre of most tissue (lungs, liver, spleen etc.)
What are the main features of tendons?
Attaches skeletal muscle to bone
Transmit muscle force to bone
Made of collagen fibres
Stiff and Strong
Structure: Collagen fibers arranged in bundles
What is the microstructure of tendons?
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 tendons?
Transmit muscle forces
Elastic energy storage / recoil
PG resists compressive stresses
What are the main functions of ligaments?
Connect bone to bone to stabilise joint
Enable proprioception
What is the structure of ligaments?
Have functional subunits that tighten or loosen depending on joint position
is not densely innervated or vascularised
Contain some blood vessels and nerves in outer covering (epiligament)
Contain proprioceptors
Transmit pain signals via type C fibers
What do ligaments 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 is the function of cartilage?
Acts as shock absorber to reduce friction
Covers and protects long bones at joints
Structural component of ribs & IV discs
What is cartilage made up of?
Made up of chondrocytes – produce large amounts of collagenous ECM, ground substance
Avascular
What are the three types of cartilage?
Elastic
Hyaline
Fibrocartilage
What are the three types of joints?
Fibrous
Cartilaginous
Synovial
Give examples of fibrous joints?
Sutures
Syndesmosis
Interosseous membrane
Give examples of cartilaginous joints
Synchondroses
Symphyses
Give examples of synovial joints
Plane Hinge Condyloid Pivot Saddle Ball and socket
What are the main features of synovial joints?
Most common type of joint
Most mobile type of joint
Joint capsule: Articular capsule (Outer) – keeps bones together structurally Synovial membrane (Inner) - contains synovial fluid
Synovial fluid reduces friction during movement
What are the role of ligaments in joint stability?
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 factors affect joint stability
Joint shape e.g. hip vs shoulder
Ligaments
Tendons
Cartilage (e.g. glenoid labrum)
What is the middle shaft of a long bone known as?
Diaphysis
What are the different parts of the bone?
Epiphysis
Physis
Metaphysis
Diaphysis
What is the periosteum?
Connective tissue covering
What is the outer cortex?
Compact bone
Cancellous bone
What are bone scans used for?
Multiple fratures and Infection
