Wormian Bones

Description

Examples of the Wormian bones (marked by asterisks) located within the lambdoid suture of the human skull. Oc: occipital bone, Lp: left parietal bone, Rp: right parietal bone

Superior view of the skull cap showing the Wormian bones in the sagittal suture and os inca bone; Ss: sagittal suture; Wb: Wormian bone; Ls: lambdoid suture; Ib: inca bone; Lda: lambda; Pb: parietal bone

Name

• Wormian Bones
• Wormian Bone
• Intrasutural Bones
• Sutural bones
• Intrasutural Bones
• Accessory Sutural Bones
• Accessory Cranial Ossicles
• Cranial Sutural Ossicles
• Fontanelle Bones
• Ossa Wormiana
• Supernumerary Cranial Bones

General

• Name given to additional small bones or bone islands sometimes found between cranial sutures
• Most commonly this is in relation to the lambdoid suture
• Literature is not clear, some refer to as abnormal only if greater than 10 in number

Epidemiology

• Widely variable
• Ranges from 10% in caucasians, 40% in Indian, 80% in Chinese
• In general, males are more frequently affected than females

Location

• Lambdoid Suture: most common
• Lambda
• Pterion: up to 12% of former anterolateral fontanelle
• Sagittal/Coronal sutures: uncommon

History

• Named after Ole Worm (Olaus Wormius), a Danish physician from the late 16th/ early 17th century

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See Also

• Accessory Bones Main
• HEENT Anatomy Main

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