According to About.com, the odontoid process serves as a pivot point for the skull and first cervical vertebrae, which allows the head and neck to rotate. The odontoid process is a projection that grows off the front portion of the second cervical vertebrae, which is also called the axis.
About.com explains that the odontoid process protrudes through a gap in the first cervical vertebrae. The first cervical vertebra, or atlas, is shaped differently than the other vertebrae in the neck. In contrast to the other vertebrae, the atlas does not have a vertebral body. Instead, the atlas has an opening that accepts the odontoid process. This arrangement allows the head and neck to rotate further than would be possible with typical vertebral joints.
Often, people hear about the odontoid process, which is also called the dens, in association with a diagnosis of a broken neck. According to Radiopaedia.org, there are three different types of fractures that occur in the odontoid process. Type I fractures occur at the tip of the odontoid process, while type II fractures occur at the base of the projection. In type III fractures, the break occurs below the start of the odontoid process, freeing the dens and a portion of the axis.
According to Wikipedia, the joint between the atlas and axis is a non-weight-bearing joint. However, during hangings, the odontoid process often fractures. The process may then strike the medulla oblongata, causing rapid death.