1. The Skeletal System
HLTAP301A

2. Skeletal System Consists of bones, joints, cartilage and ligaments
Bone tissue is living and active

3. Functions of the skeletal system
Gives body shape and support
Bones provide an internal framework
Support and anchor soft tissue
Provide points of attachment for skeletal muscles
Protects internal organs
Bones protect soft body organs
Cranial bones / brain
Vertebrae / spinal cord
Rib cage / organs of the thorax
Provides movement and leverage
Muscles attach to bone
When they contract they pull on bones and produce movement

4. Functions of the skeletal system
Mineral homeostasis
Bones release minerals into blood to maintain mineral balance
Calcium must be present in blood for nervous system to transmit messages, muscles to contract and for blood to clot
Blood cell production
Red bone marrow produces red and white blood cells and platelets
Storage
Lipids are stored in yellow bone marrow for energy
Mineral storage
Calcium
Phosporous

5. Structure of skeletal system
Bone is living tissue with a blood supply
Productive factory and store house
Hardest connective tissue
Known as osseous tissue
206 bones

6. Bone tissue Compact bone Hard and dense
Forms shaft of bone and outer surfaces of other bone
Haversian canals are where osteocytes are arranged in circles around blood vessels and surrounded by protein fibres, calcium and other minerals

7. Bone tissue
Cancellous bone tissue is hard but less dense than compact bone
Honey comb appearance
Contains red bone marrow and produces blood cells
Found in ends of long bones and middle of short flat and irregular bones

8. Bone tissue
Yellow marrow is mainly found in centre of long bones and is mainly made of fat
The name of the membrane covering the bone is periosteum
Inner layer contains cells called osteoblasts that are essential for bone formation

9. Bones of the skeleton Two parts to the skeletal system Axial skeleton
Upright central part of the body
Consists of skull, vertebrae, ribs and sternum
Appendicular skeleton
bones of lower and upper limbs, shoulders and pelvic girdle

11. Classification of bones
Long bones
Shaft with head at both ends
Mostly compact bone
Femur
Tibia
Fibula
Humerus
Ulna
Radius

12. Classification of bones
Short bones
Roughly cubed shaped ends
No cavity
Wrist
Ankle

13. Classification of bones
Flat bones
Thin flattened and usually curved
Two thin layers of compact bone with layer of cancellous in between
Skull
Ribs
Sternum

14. Classification of bones
Irregular bones
Have 2 or more different shapes
Vertebrae
Hip
Some facial bones

15. Did you know?
When you hit your elbow and get a sharp pain associated with the “ funny” bone that you are actually hitting the ulnar nerve
This nerve is unprotected and lies over the distal end of the humerus
Probably called funny because it is associated with the humerus

16. Joints (articulations)
Point of contact where 2 or more bones meet
Provide flexibility to the skeleton
Help together by ligaments

17. Ligaments
Bundles of dense, fibrous tissue forming rope like structures
Contain a few elastic fibres enabling limited stretching and great strength
Function is to attach bone to bone providing stability to joints and limit the range of movement

18. Cartilage
Firm smooth slightly flexible tissues forming pads in some joints
Vertebrae
Knee
Covers ends of bones with smooth lining
Between ribs and sternum
Main function is to keep bones aligned

19. Classification of joints
Immovable joints (synarthroses)
Mainly axial skeleton
Suture lines in bones of skull
Slightly movable joints (amphiarthroses)
Between vertebrae or symphysis pubis
Freely moveable (diarthroses)
Variety of shapes
Mainly in limbs
Allow several types of movement

20. Classification of joints
Structural
Fibrous bones
Held together by fibrous connective tissue
Teeth in sockets
Cartilagenous
Bones help together by cartilage
Synovial
All joints of limbs between ends of bones

21. Synovial joints All synovial joints have common characteristics
Articular cartilage (hyaline)
Covers the ends of bones forming the joint
Fibrous articular capsule
Capsule of fibrous connective tissue
Lined with synovial membrane
Secretes synovial fluid
Encloses joint surfaces

22. Synovial joints All synovial joints have common characteristics
Joint cavity contains sinovial fluid
Lubricates the bones in the joint
Enclosed by articular capsule
Supporting ligaments
Reinforcing the fibrous capsule
Stabilise the joint

23. Synovial joints Examples Ball and socket (hip) Hinge (elbow)
Saddle (thumb)
Ellipsoid (wrist)
Pivot (neck)
Gliding (vertebrae)

25. Disorders Arthritis – inflammation of a joint
Bursitis – inflammation of bursae – small sac of fibrous tissue containing synovial fluid which reduces friction
Cancer – commonly myeloma
Dislocation – displacement
Osteomyelitis – inflammation of bone with infection
Osteoporosis – porous bone