L3 PT YMCA Awards at The Park Centre

Bones Revision Questions

Five different types (shapes) of bones, give an example of each:

1

2

3

4

5

Three different types of joint, give an example of each:

1

2

3

Bone formation questions:

What are osteocytes?

What are osteoblasts?

What are osteoclasts?

Why are youngsters’ bones more flexible?

Where is marrow stored within the bone?

What is the bone deterioration disease that sometimes affects elderly people, why does this happen?

Bone and Joint Information

Bones have five shapes:

Long – femur, radius, ulna

Short – tarsals, carpals

Flat – skull, ileum

Irregular - vertebra

Sesamoid – patella, foot

Bone formation starts in the womb and is controlled by endocrine, physical and biological processes. Young bone is formed of mainly cartilage, which is a soft elastic connective tissue. Normal bone forms around the template of this cartilage, this is known as ossification.

Osteoblasts secrete a substance called osteoid which hardened by mineral salts. As the cartilage cells die more osteoblasts take their place. Ossification continues until there is only a thin strip of cartilage remaining, this is what we know as the epiphyseal plate, where further growth can occur. This continues for around 20 years.

Bone is constantly being remodelled throughout life. In younger years more osteoblasts are laid down. Osteoclasts are cells that help to break down the calcium in bone so that it can be reabsorbed into the blood stream.

The osteoclasts break down bone in the epiphysis; if this continues the bone will become weak at that point and more prone to fracture. A bone that is put under constant stress, such as weight and load bearing will have more osteoblasts activity to build and strengthen the epiphysis.

Bones are remodelled at different rates depending on their usage, the femur because of its activity is effectively replaced roughly every six months.

  • Osteocytes are mature bone cells that give the bone its hardness and density.
  • Diaphysis has compact (cortical) bone, medullary cavity(canal). The medullary cavity in the middle of the bone is filled with bone marrow, where blood cells are made.
  • Epiphysis has spongy (cancellous) bone and articular cartilage.
  • Epiphyseal (growth) plates lie in between the diaphysis and epiphysis.
  • Periosteum covers the bone like cling film, and contains blood vessels and nerves.
  • Bones act as reservoir for calcium and phosphorous.

Joints:

Moveable (synovial) – knee, shoulder

Joint capsule, ligaments, articular cartilage, joint cavity, synovial membrane, synovial fluid (sacs),

Partly moveable (cartilaginous) - spine

Immoveable (fibrous) – skull

Synovial Joints

Hinge (one plane) – knee, elbow, phalanges

Pivot (multi plane, rotation) – Atlas/Axis, Radius/ulna

Condyloid (multi plane) – Wrist, knuckles (metacarpal/phalanges)

Saddle (two planes) – thumb

Ball and socket (all directions, less stable) – Shoulder joint, Hip

Gliding/Plane one plane, limited range) – AC joint, carpals, tarsals