Bone types

There are five bone types involved in the human movement system: long, short, flat, irregular, sesamoid and. The following concern us most: long, short and sesamoid.

Long:

• Long, cylindrical shaft with irregular or widened ends.
• Consist primarily of composit bone for strength and stiffness.
• Such bones include the femur, humerus and metacarpals. The epiphysis, or end of the long bones, is the primary site for bone growth.
• Until its epiphyseal plate fuses in adulthood, it is vulnerable to injury. This is why weight-bearing exercise can be dangerous for children, however on the flip side it does allow children to develop stronger healthier bones.

Short:

• Appear somewhat cubical in shape being similar in length and width.
• Consist primarily of spongy bone to maximise shock absorption such as in jogging, jumping or punching.
• These include the small bones of the wrists (carpals) and upper foot (tarsals).

Sesamoid:

• Small, and often round, they are found embedded in joint capsules or where a tendon passes over a joint where there is considerable friction or tension.
• They help improve leverage as well as protecting the joint from damage. The most notable being the patella, or "knee-cap".

Types of bones in the body (click to enlarge). Image from Wikipedia.

Articles within this series

• Breakdown of the skeletal system
• Bone remodelling
• Bone types
• Surface markings

Lyle Richardson,
Gym Pal - Your friend in the world of fitness