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

Spongy bone is located in the inner layer of the epiphysis and consists of trabeculae. In the spacings between the tabeculae, red bone marrow is located. The function of spongy bone is to produce red blood cells.

Structure of compact bone

Compact bone forms the diaphysis and makes the outerlayer of epiphysis. It is composed of osteons and its function is to provide strenght and protection.

Why is bone connective tissue?

Bone is composed of cells suspended within a non living matrix. The matrix is made of inorganic salts like calicum and phosphate.

What type of tissue is cartilage?

Connective tissue

Composition of the cartilage matrix

Collagen fibres embedded in chondrin

Function of collagen

Provides flexibility

Function of chondrin

Provides strength

Role of chondroblasts

Produce the matrix

Role of Chondrocytes

Mature cartilage of cells trapped in the lacunae and maintains the matrix

How does cartilage remove waste and take in nutrients

The perichondrium contains blood vessels for cartilage. It is a fibrous membrane that covers external surfaces. All nutrients and waste must diffuse through the matrix. Diffusion is a slow process, so chondrocytes have a slow rate of metabolism and cell division and therefore will heal slowly

Hyaline Cartilage

Structure:

• Closely packed collagen fibres

• Very fine and undistinguishable under a microscope

Location

• Rings of trachea and bronchi

• ribs

• end of long bone (articular cartilage)

Suitability to function

• provides strength and flexibility

• smooth surface reduces friction in joints

Smooth cartilage

Structure:

• collagen fibres loosely packed

• elastic fibres present

Location

• ear

Suitability to function:

• provides flexibility and support / elasticity

Fibrocartilage

Structure:

• parralel bundles of thick collagen fibres giving coarse appearance

• Fibres not as compact as hyaline thus can be slightly compressed

Location

• Between vertebral disks of spinal column

• meniscus of knee

• pubic symphysis

Suitability to function:

• withstand high pressure

• support body weight

Joint

The point where bones come together

Ligaments

The structure that connects bone to bone

Tendons

The structure that connects bone to muscle

Examples and degree of movement of Fibrous Joint

• no movement

• held in place by fibrous connective tissue

• Strong and difficult to damage

Structures of the skull

Examples and degree of movement of Cartilaginous Joints

• little movement

• held in place by cartilage

Pubic symphysis, adjacent vertebrae

Examples and degree of movement of Synovial Joints

• generally large range of movement

• limited by ligaments, tendons, muscles and bone around the joint

Ball and socket (hip and shoulder), hinge (elbow and knee)