Types of Bones (Bone Types)
Types of Bones or 'Bone Types' can be classified according to the shape of the bone. The shape of bones reflect their functions. When describing specific bones it can be useful to start by stating the type of bone in terms of its shape,
e.g. "the scapula is a large flat triangular bone".
The main 5 types of bone (in terms of bone shape) are listed in the following table together with brief descriptions and examples of each. First remember the list of types of bones:
- Long Bones
- Short Bones
- Flat Bones
- Irregular Bones
- Sesamoid Bones
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Bone types |
(Classified by shape) |
|
Description |
Example(s) |
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. |
|
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). |
|
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.
- 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). |
|
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.
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|
|
Extra bone type |
(Classified by location) |
|
Meaning / Description |
Example(s) |
(6.) |
Sutural Bones |
Sutural
bones are very small bones located
specifically within the sutural joints between the cranial bones. They are classified
by their location - hence the name of this type of bone - rather
than by their shape. The number of sutural
bones varies considerably
because different people have different numbers of sutural bones |
All sutural
bones are un-named
bones.
|
|
Note: This table lists the main 5 types of bones but the important thing is to learn about the different types of bones (not the numbers).
Some questions may ask for only 4 types of bones and some texts include 6 types of bones including sutural bones. |
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This is the end of this page about bone markings and the features on bones. Information about the structure and functions of bones, the 206 human bones, cranial and facial bones, bones of the feet and hands and skeletal disorders are also included.
