Irregular Bone

Any bone that is not grouped within the other categories of bone such as long, short, or flat is categorized as an irregular bone. With different shapes and such a wide variety, irregular bones serve several different purposes in the body.
The Vertebra
Other bone types include long bone, short bone, and flat bone.


Because irregular bone is a category used for bones that simply do not fit in the others, irregular bones can be found in diverse places within the body, mostly down the spine.

Irregular bones include:



All irregular bones differ from one another in size and shape while some match each other in function.
The vertebra make up the vertebral column with a front body section that makes up the vertebral body as well as a back section. With a vertebral arch they support seven processes, four articular, two transverse, and one spinous.
A larger triangle bone at the base of the spine known as the sacrum sits between the two hip bones.

Each of the irregular bones are constructed by spongy bone that is coated by a thin layer of compact bone.


  • Protection
  • Skeletal muscle anchors
  • Support


Irregular bones work to protect nervous tissue, such as in the way that vertrbra connected together to make the vertebral column protect the spinal cord. 34 vertbrae, the sacrum, and the coccyx all together construct the vertebral column in order to hold the spinal cord.
spine3-BB.jpg Illu_vertebral_column.jpg


Irregular bones in the throat work to support the trachea as well as the pharynx. With the pharynx in the throat posterior to the mouth where both food and air pass through, irregular bones maintain its shape. The trachea further down only passes air to the bronchial tubes where irregular bones perform the same function.
The Hyoid Bone an example of an irregular bone