Skeleton Flashcards
What is the function of the skeleton?
Support Protection Shape Movement / Locomotion Source of materials Supports weight against gravity Reinforced by action of muscles Divided into units for movement Variations dependent on whether bipedal, quadrupedal, swimming, flying.
What are the three parts of the skeleton?
- Axial =
skull, vertebral column
(cervical; lumbar; sacral; coccygeal), ribs & sternum - Appendicular =
bones of the limbs,
includes: pelvic girdle, and pectoral girdles - Visceral = skeleton in soft tissues e.g. bones of the inner ear
os cordis (in ox heart) os penis (in dog, mouse)
What is the skull and what is it made up of?
Skull - protects the brain & major sense organs – Human: 29 head bones • 8 Cranial • 14 Facial • 1 Hyoid bone • 6 Auditory ossicles
What is the vertebrae and what is it made up of?
Vertebral column -protects the spinal chord – Human: 33 • 7 cervical • 12 Thoracic • 5 Lumbar • 5 (fused) Sacrum • 4 (fused) coccyx
What is the thorax and what is it made up of?
Thorax - protects heart & lungs and aids respiratory movements – Human: 24 (12 pairs) • 24 ribs – 14 true – 6 false – 4 floating • Sternum
What are the extremity bones?
Upper extremity bones: – Clavicle – Scapula – Humerus, radius, ulna • 16 Carpal bones • 38 Metacarpus and phalange bones Lower extremity bones: – Hip – Femur, patella, tibia, fibula • 14 Tarsal bones • 38 Metatarsus and phalange bones
What is skeletal tissue?
Includes bone, cartilage, ligaments and tendons
– Functional differences are primarily due to differences in the proportion of ground substance and fibres in the extracellular matrix.
What is bone?
Is a hard connective tissue
Matrix produced by bone cells – osteocytes Becomes impregnated with Ca salts (65-75 % of
the matrix is inorganic) and collagen fibres.
Adapted to withstand forces.
(Ca ≠ compression, collagen ≠ tension)
Low metabolic rate
Highly adaptable, meeting changes as required
What are the two types of bone?
1.Compact (Cortical) – Hard – Cortical – Long bones 2.Cancellous (Trabecular) – Haematopoietic or fatty marrow
What are the five types of bone?
- Long
Connected with large movement Long and cylindrical Appendicular skeleton
Femur, humerus - Short
Smaller, more complex movements Almost cube shaped
Carpals and tarsals - Flat
protect the internal organs
skull (cranium), ribs, scapula, sternum, pelvic girdle. - Irregular
irregular in shape
vertebrae and some facial bones. - Sesamoid
small bones held within tendons
include the patella and pisiform bone of palm
What is the periosteum and what are its layers?
Periosteum Covers most of a long bone (Except regions covered by articular cartilage or ligamentous, tendonous or capsular attachments) – Outer, fibrous layer • Permeated by blood vessels and nerve fibres • Supportive – Inner, osteogenic layer • Appositional growth • Repair
What is the microstructure of bone?
Microstructure
– Cells
– Organic extracellular matrix – Inorganic extracellular matrix
What are osteoprogenitor cells?
Osteoprogenitor cells
– Derived from mesenchyme cells
– Found in the periosteum and endosteum
– Mitosis and differentiation into bone cells (osteogenic potential)
What are osteoblasts?
Osteoblasts – First cells to develop from the osteoprogenitor cells – Cover majority of bone surface – Formation of organic matrix – Osteoid – Abundant ER, ribosomes, Golgi apparatus, mitochondria – High rate of metabolic activity – Produce • Collagen • Proteoglycans • Noncollagenous proteins
What are osteocytes?
Osteocytes
– 10% of osteoblastic population • Enclosed in matrix
• Mature to osteocytes
– Fewer metabolic cellular components
– Cytoplasmic processes into surrounding matrix
– Fill canaliculi
– Intricate transport and communication system
– Flow of mineral ions: extracellular space around osteoblasts => osteocytes => surrounding extracellular space
What are osteoclasts?
Osteoclasts – Originate from blood monocytes – Bone reabsorption – Large, multinucleated cells – Near bone surface – Reside within Howship’s lacunae – Abundant Golgi apparatus, Golgi vesicles and mitrochondria – Ruffled Border – Acid phosphatase and collagenase production – Dissolve minerals – Remove organic matrix
What is the matrix and what is it made up of?
Supporting structure for deposition and crystallisation of inorganic salts • Collagen • Proteoglycan • Glycosaminoglycan • 21% of bone by weight • 71% inorganic • 8% water
What is the inorganic matrix made up of?
Mineral portion – Small crystals – Mainly Ca10(PO4)6(OH)2 Also: – Carbonate – Magnesium – Fluoride – Citrate Hydroxyapatite in close apposition to organic matrix => mechanical strength of bone
What is the Haversian system?
Haversian system/Osteon Fundamental unit of bone:
Haversian canal
Blood vessels
Nerve fibres
Lymphatic channels Lamellae of mineralised bone Lacunae (little hollows)
• Oseocytes
Canaliculi (between lacuna)
What are the compact bones Haversian systems?
Concentric circles built up around a central canal Layers of bone called lamellae
Osteocytes sit in lacunae in the matrix
Interconnections between lacunae and central canal are called canaliculi
What are the four types of bone marrow?
- Red = blood–forming (Erythroctyes)
- Yellow = fatty and not blood-forming but can
be converted in times of stress - White = hard fatty tissue for storage
- Gelatinous = degraded semi-fluid found in senile animals!
What is cartilage and where is it found?
A pre-cursor to bone during embryonic development.
A supporting connective tissue, as is bone.
An important structural component of the skeleton, much softer and more flexible than bone.
Found in various places
– Covers joint surfaces
– Nose
– Pinna
– Ribs
– Bronchialtubes
– Intervertebral discs
Semi-rigid support
Primarily matrix base with fibrous or elastic fibres embedded (can be 60-80% water)
What is cartilage made up of?
Matrix of water,collagen, proteoglycans and elastin fibres
Avascular Aneural
Nutrients to cells via diffusion
Very low metabolic rate. Does not repair
What are the types of cartilage?
Hyaline
Fibro-cartilage
Elastic cartilage
