Feb 8, 2011 - Throw me a Bone Here! - Extra Bones?

Reminder - The Histology Comprehensive Test is this Friday 2/11. It will be run as a practical exam.

Wormian Bones & Accessory Bones

http://upload.wikimedia.org/wikipedia/commons/9/93/Wormian_bones.jpg

Wormian bones are a subset of the small intrasutural bones that lie between the cranial sutures formed by the bones of the skull vault. The title Wormian bones is given to abnormal intrasutural bones that are typically found around the lambdoid suture.
Erroneously, these bones are named after the person who was supposed to have first described them:

• Ole Worm (1624-1639): professor of Anatomy at Copenhagen, Denmark

http://radiopaedia.org/articles/wormian-bones

Accessory Bones

The image above shows a common form of often problematic accessory bone.

     These are "extra" bones resulting, most often, from altered patterns of ossification. The accessory bones (also called ossicles) occur most often in the hands, wrists and feet. Examples include the os naviculare secundarium, carpal boss, os trigonum, os vesalianum, os intermetatarsale, and os supratrochleare dorsale. These ossicles are generally not considered significant and are believed to represent variations of normal development. It is not uncommon for both the wrists and/or the feet to contain extra small ossicles, that occasionally cause pain. It is important to note that other problems such as avulsions or chip fractures may sometime be misidentified as accessory bones.    http://www.medcyclopaedia.com/library/topics/volume_iii_1/a/accessory_bones.aspx

 Fun Fact: The soft spot(s) on a baby's head called fontanelles are the places that Wormian bones most often
                form due to the pattern of ossification in the baby's head.