1.

Long Bones

'Long bones' are longer than they are wide,

i.e. length > diameter.

They consist of a shaft - which is the main (long) part and variable number of endings (extremities), depending on the joints formed at one or both ends of the long bone.

Long bones are usually somewhat curved - contributing to their mechanical strength.

Femur (leg bone)

Tibia (leg bone)

Fibula (leg bone)

Humerus (arm bone)

Ulna (arm bone)

Radius (arm bone)

2.

Short Bones

'Short bones' can be approximately cube-shaped,

i.e. length is similar to width / depth / diameter.

The most obvious EXAMPLES are the carpal bones (of the hands / wrists) and the tarsal bones (of the feet / ankles).

Scaphoid bone (wrist bone)

Lunate bone (wrist bone)

Hamate bone (wrist bone)

and other wrist bones = carpal bones

Cuboid bone (ankle bone)

First Cuniform bone (ankle bone)

Second Cuniform bone (ankle bone)

and other ankle bones = tarsal bones

3.

FLAT Bones

'Flat bones' have a thin shape and, in some cases, provide mechanical protection to soft tissues beneath or enclosed by the flat bone e.g. CRANIAL bones that protect the brain.

Flat bones also have extensive surfaces for muscle attachments e.g. scapulae (shoulder) bones.

Cranial bones (protecting the brain) e.g.

Frontal bone

Parietal bones

Sternum (protecting organs in the thorax)

Ribs (protecting organs in the thorax)

Scapulae (shoulder blades).

4.

Irregular Bones

'Irregular bones' have complicated shapes that cannot be classified as 'long', 'short' or 'flat'. Their shapes are due to the functions they fulfill within the body e.g. providing major mechanical support for the body yet also protecting the spinal cord (in the case of the vertebrae).

Atlas bone

Axis bone

and other vertebrae

Hyoid bone

Sphenoid bone

Zygomatic bones

and other facial bones.

5.

Sesamoid Bones

'Sesamoid bones' develop in some tendons in locations where there is considerable friction, tension, and physical stress. Typical areas in which they may form include the PALMS of the hands and the soles of the feet. The presence, location and and quantity of sesamoid bones varies considerably from person to person.

Most sesamoid bones are un-named.

Only one type of sesamoid bone is present in all normal HUMAN skeletons so has a name. That is the patella (singular), patellae (plural). Patellae are also called 'kneecaps'. Complete human skeletons include 2 of these, one in each leg.