Odontoid process

Odontoid process (also known as the dens) is a protrusion (process) of the axis (second cervical vertebra) that is held in place by ligaments. It allows the head and the first cervical vertebra to rotate around it. The term "odontoid" comes from the Greek odontoeidēs, meaning "tooth-like", due to the process's tooth-like shape.

Structure

The odontoid process is a bony cylindrical eminence, which rises perpendicularly from the upper surface of the body of the axis. It has a slight constriction or neck, where it joins the main body of the vertebra. The apex is pointed and gives attachment to the apical ligament, which secures the tooth-like process to the occipital bone. The body is large and has a rough anterior surface.

Development

The odontoid process is ossified from two centers; one for the body and one for the odontoid process. The latter appears in the under surface of the process about the seventh week of fetal life, and joins the body about the third year.

Clinical significance

Injury to the odontoid process can be life-threatening because it may cause instability of the cervical spine, leading to spinal cord injury. Fractures of the odontoid process are classified into three types according to the location of the fracture line.

See also

• Axis (anatomy)
• Apical ligament
• Occipital bone

External links

• Anatomy expert
• Wheeless' Textbook of Orthopaedics

Odontoid process Resources
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