Introduction to the Skeletal System

Topics Covered

Functions of the skeletal system

Types of bone tissue

Composition of bone

Bone morphology

Bone features

Functions of the Skeletal System

·      Support body’s soft tissues and internal organs

·      Stores materials like calcium.

·      Blood cells are produced in bone marrow

Types of Bone Tissue

·      Compact bone or dense bone (Linked to figure 6.12- Diagram of Compact Bone)

·      Spongy bone or cancellous tissue (Linked to figure 6.13- Diagram of Spongy Bone)

Composition of Bone

·      Organic Material

o   30%

o   Cells and collagenous fibers

o   Gives bone a degree of flexibility

·      Inorganic material

o   70%

o   Hydroxyapatite

§  hydroxyapatite (HA), is a naturally occurring mineral form of calcium apatite. Commonly found in bone and teeth so for that reason it is used a lot in filler to replace amputated bone or as a coating to promote bone growth into prosthetic implants.

o   Enables bone to support the weight of the body without sagging

Bone Morphology (Linked to figure 6.7- Anatomy of a long Bone)

·      Periosteum –Tough, fibrous membrane containing 2 layers (location of nerve and blood vessels; anchoring point for tendons and ligaments).

o   Outer fibrous layer

o   Inner cellular layer that produces osteoblasts

·      Osteoblast – bone forming cells (Linked to figure 6.11- Bone Cells)

o   Originate from stem cells and form bone from collagen fibers and calcium salts.

·      Osteoclast – bone dissolving cells (Linked to figure 6.11- Bone Cells)

o   Remove calcium/minerals by acid phosphatase and HCl

·      Osteocytes – former osteoblasts that have become trapped in the matrix they deposited (Linked to figure 6.11- Bone Cells)

o   Mature bone cells that help to reshape the bone after stress.

·      Epiphyses

o   Spongy bone present at the proximal and distal ends of a long bone

o   Enlarged to provide added surface area for the attachment of tendons

o   Covered with a layer of hyaline cartilage (articular cartilage) that helps reduce friction at the joint

·      Diaphysis

o   Shaft of the long bone

o   Compact bone

o   Marrow cavity – space inside

Bone Features (Linked to figure 6.10- Bone Features)

·      Each bone has certain anatomical features on the surface called bone markings or surface markings

·      Head – rounded articular projection supported on the neck of the bone

·      Neck – a constriction below the head

·      Tubercle – a relatively small bump on a bone

·      Tuberosity – a relatively large bump on a bone

·      Fossa (cavity) – a shallow depression in a bone

·      Groove – an elongated depression

·      Trochanter – a very large projection

·      Condyle – an irregular, smooth surface that articulates with another bone

o   Purpose: articulation

·      Epicondyle – a projection above a condyle

o   Purpose: muscle attachment

·      Process – a projection from the surface of the bone

·      Spine – a pointed process

·      Crest – prominent ridge

·      Foramen – Round passageway for blood vessels or nerves

·      Canal – Passageway through substance of bone

·      Fissure – Elongated cleft

·      Sinus – Chamber within bone usually filled with air

·      Facet – Small flat, articular surface