Accessory Bones of the Spine

Description

Normal anatomy and Os Odontoideum.

Ferguson radiograph in a 35-year-old man. AP radiograph angled cranially at 30° allows better characterization of the transverse processes of L5. LSTVs have been classically described as best imaged by using Ferguson radiographs.

Lateral view X-ray imaging of the cervical spine demonstrating the existence of an ossicle within the nuchal ligament at the level of C5 vertebral spinous process (arrow).

Names

• Accessory bones of the spine
• Ossicles of the spine
• Sesamoid bones of the spine

General

• This page reviews accessory bones of the cervical, thoracic and lumbar spine

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Accessory Bones

Occipital Vertebra

• Rare anatomic variants of the occipital bone
• Paramastoid Process
• Basilar Process
• Prebasioccipital Arch
• Third Condyle

Limbus Vertebra

• Well corticated and unfused secondary ossification center of a vertebral body

Accessory Ossicle of the Anterior Arch of the Atlas

• Normal variant of the anterior arch of Atlas

Oppenheimer Ossicle

• Accessory ossicle associated with the facet joints of the spine, typically lumbar

Os Odontoideum

• Anatomic variant of the odontoid process of the Axis

Persistent Ossiculum Terminale

• Persistent unfused odontoid tip ossification center

Sesamoid Ossicles of the Nuchal Ligament

• Relatively common anatomical variant in which a sesamoid bone is found within the nuchal ligament

Lumbosacral Transitional Vertebrae

• Relatively common anatomic variant in which a vertebral level is lumbarized or sacralized

Epitransverse Process of the Atlas

• Rare anatomic variant of Atlas
• Consists of bony exostosis which extends cranial from the transverse process of atlas to articulate with occiput

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Clinical Significance

• Needs to be updated

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See Also

• Accessory Bones Main
• Radiology Main
• Cervical Spine Anatomy
• Back Anatomy Main

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