Skeletal Systems and Bones Flashcards
The skeletal framework of the body is separated into:
- Axial Skeleton (skull, vertebral column, ribs, and sternum)
- Appendicular skeleton => limbs and limb girdles
Mention the function of the skeletal system.
- Supports the body and the muscles
- Protect and encloses visceral organs
- Helps in movement
- Blood formation in bone marrow
- Stores minerals and salts like calcium, phosphorus
- Removes foreign and toxic heavy metals
Mention the types of bone shapes.
- Long: arm and leg bones – tubular
- Short: carpal, tarsal bones – cuboidal (slight movement – sliding)
- Flat: cranial bones, sternum
- Irregular – vertebrae, bones of face
- Other: pneumatic, sesamoid, accessory
The adult human body has ______ bones.
206
Describe the features of a long bone.
- Periosteum: outer fibrous covering - articular cartilage at joint
- Compact Bone: 3/4 of weight
- Spongy Bone: 1/4 of weight
- Medullary Cavity:
- Encircled by endosteum
- Contains bone marrow (red/yellow)
- Epiphysis
- Diaphysis
- Epiphyseal Plate: separates epiphysis and diaphysis
- Made up of cartilage - degrades
- Located in the metaphysis
- Nutrient Foramen: opening for nutrient vessel
Mention the types of bones based on their shape.
- Long: arm and leg bones – tubular
- Short: carpal, tarsal bones – cuboidal (slight movement – sliding)
- Flat: cranial bones, sternum
- Irregular – vertebrae, bones of face
- Other: pneumatic, sesamoid, accessory
- Note: there are 206 bones in adult body
Describe the feature of flat bones.
- External and internal layer of compact bone
- Middle layer: spongy bone => no marrow cavity but long-life depository of red bone marrow
- Spongy bone called diploe: contains air-filled bubbles called trabeculae
Describe the composition of bones.
- Cells
- Osteoblasts: bone producing
- Osteoclast: bone dissolving cells
- ECM:
- 2/3 inorganic: mineralised ground substance
- 85% hydroxyapatite (calcium phosphate)
- 10% calcium carbonate
- Other
- 1/3 organic: collagen fibres, protein, carbohydrate molecules
- Combination provides strength and resilience
- Minerals resist compression; collagen resists tension
- 2/3 inorganic: mineralised ground substance
Trabecular/Spongy bone are good at resisting _________ (arranged vertically).
Cortical/Compact bone - good at resisting _________
static forces
dynamic forces
Describe the type of cartilages.
Cartilage are precursors of most bones - mostly avascular and aneural
- Hyaline:
- On articular surfaces
- Parallel collagen fibres
- Glossy appearance
- Fibro
- Forms discs, meniscus, labrum
- Dense, irregular collagen fibres
- Elastic
- Elastic collagen fibres
- External ear, parts of larynx
Describe the process of intramembranous bone formation
Intramembranous bones are usually flat bones of the skull, clavicle, or mandible. It has a fibrous tissue precursor
- Mesenchyme condenses into a sheet of soft tissue => network of soft trabeculae
- Osteoblasts gather on the trabeculae to form osteoid tissue (uncalcified bone)
- Osteoclasts remodel the centre to contain marrow spaces & osteoblasts remodel the surface to form compact bone
- Mesenchyme at the surface give rise to the periosteum
Describe the process of endochondral ossification at primary centres.
Endochondral bone: any bone that develops in and replaces cartilage, usually in long bones.
It has a hyaline cartilage precursor
- Bone first appears in the middle of the shaft
- Cartilage, progressively replaced by bone, extending towards the ends (epiphyses)
- Bone simultaneously formed in periosteal and endosteal layers, to remodel the medullary cavity
- Note: most other bones have primary centres of ossification and bone is laid down in a similar manner
- Note:
- Diaphysis forms the shaft
- Epiphysis forms the ends
- Metaphysis forms part of the diaphysis adjacent to epiphysis at each end – site of remodelling and high metabolic activity
Describe the role of the nutrient artery.
- Invades primary centre – bringing osteogenic cells
- Through the nutrient foramen
- Major artery supplying long bone
- Canal of nutrient foramen directed away from growing end
Describe the process of the secondary centre of ossification.
- Appear at the epiphysis
- Epiphyseal arteries and osteogenic cell invade epiphysis
- Deposit osteoblast, erode the cartilage in the epiphysis
- Epiphyseal growth plate (disk)
- Continued longitudinal growth occurs at the epiphyseal growth plate - mesenchyme
- When fully developed, the only remaining cartilage is the articular cartilage at the ends of the bone – epiphyseal line
- Clinical Significance
- Indicate bone growth
- If damaged, may interrupt growth at site
Compare between pressure and traction epiphysis.
- “Pressure epiphysis” – associated with joints
- “Traction epiphysis” associated with attachments of tendons or ligaments
Mention the neurovascular supply of the bone.
- Nutrient
- Periosteal
- Metaphyseal
- Epiphyseal
- Note:
- When epiphysis growth is still ongoing, the epiphyseal arteries are “end arteries” – no connection with other arteries in the bones
- When the metaphyseal cartilage degrades, the arteries may anastomose with the entire bone artery system
- Bone receives abundant sensory and pain nerve fibres
- Lymph vessels accompany blood vessels
Describe the type of fractures
- Associated with tearing and stripping of periosteum
- Note: Bone will try to heal directly after fracture à that’s why broken bones need to be corrected
