The
irregular bones are bones which, from their peculiar form, cannot be grouped as
long bone,
short bone,
flat bone or
sesamoid bone. Irregular bones serve various purposes in the body, such as protection of nervous tissue (such as the
vertebrae protect the
spinal cord), affording multiple anchor points for
skeletal muscle attachment (as with the
sacrum), and maintaining
pharynx and
trachea support, and
tongue attachment (such as the
hyoid bone). They consist of
cancellous tissue enclosed within a thin layer of
compact bone. Irregular bones can also be used for joining all parts of the spinal column together. The spine is the place in the human body where the most irregular bones can be found. There are, in all, 33 irregular bones found here.