The Musculoskeletal System YR 11

Functions of the Skeleton

1. Protection: Protects underlying organs

2. Support : Provides a scaffold to support the weight of the body

3. Movement : Facilitate movement by attachment to muscles

4. Produces: Blood cells are produced in the bone marrow

5. Storage : Stores and releases minerals and fats

Axial Skeleton

• Provides the main support for erect posture and protects the central nervous system as well as organs contained within the thorax

• Skull, Vertebral column, ribs and sternum

Appendicular Skeleton

• Allows for the atriculation of the limbs with the axial skeleton

• Pectoral girdle (shoulders), pelvic girdle (hip), upper and lower limbs

Articulation

Allows varying degrees of movement while staying attached

Diaphysis

• Shaft of bone

• Composed of compact bone

• Hollow

Epiphysis

• Enlarged ending of the bone

• Composed of compact bone on the outside and spongy bone on the inside

• Covered in articular cartilage

Compact Bone

• Dense bone structure

Spongy Bone

• Less dense bone structure

Periosteum

• Dense, white, fibrous outer covering of the bone

• Covers long bone except in locations of articular cartilage

Medullary Canal

• Hollow section of the diaphysis

• Surrounded by compact bone

• Contains yellow bone marrow

Yellow bone marrow

Fat storage site

Red bone marrow

• Located in the space in spongy bone

• Site of blood cell reproduction

Articular Cartilage

• On epiphysis where bone articulates with another bone

Why is bone alive

• It is made of living cells : Osteoblasts, Osteoclasts, Osteocytes that continuously build and repair bone tissue

• It contains blood vessels that deliver nutrients and remove waste

What tissue type is bone?

• Connective tissue as cells are suspended within a non-living matrix

• The matrix is made of : inorganic salts of calcium and phosphate which increases the strength and rigidity hence making it the hardest connective tissue

Function of Osteoclasts

Reabsorb bone

Function of Osteoblasts

Forms the bone matrix

Function of Osteocytes

Maintain bone tissue

Osteons

Microscopic unit that make up bone marrow

Central Canal

• Contains blood capillaries, nerves and lymph vessels

• Runs through the centre of each osteon

Lamellae

• Concentric layers of bone matrix that are surrounded by the central canal that is made of collagen and fibres and calcium phosphate

Lacuna

Small spaces in the lamellae which each contain an osteocyte

Canaliculi

Tiny canals that run between lacunae allowing communication between osteocytes.

Where is spongy bone located

Epiphysis

Trabeculae

Bony plates found within the spongy bone

Structure of spongy bone

Within the lacuna of trabeculae, osteocytes are located. In the space between the trabeculae red bone marrow is located. It is here where red blood cells are produced.