Bicarbonate is a base and critical to neutralizing the acid coming into the small intestine from the stomach. The mechanism underlying bicarbonate secretion is essentially the same as for acid secretion parietal cells and is dependent on the enzyme carbonic anhydrase.
The vertebral column (also known as the backbone or the spine), is a column of approximately 33 small bones, called vertebrae. The column runs from the cranium to the apex of the coccyx, on the posterior aspect of the body. It contains and protects the spinal cord.
A craniovertebral joint is exactly what it sounds like: a joint that permits movement between the vertebral column and the skull. The ligaments in the spine support and reinforce the joints between the vertebrae. The atlas and axis in particular work with the ligaments to move the neck. The atlas and the occipital bone form the atlanto-occipital joint, which allows neck flexion. When you nod your head as if to say yes, that is neck flexion. The atlas and axis form the atlanto-axial joint, which allows head rotation.