The vertebral column consists of a series of bones called vertebrae linked together to form a flexible column with the skull at one end and the tail at the other. Each vertebra consists of a ring of bone with spines (spinous process) protruding dorsally from it. The spinal cord passes through the hole in the middle and muscles attach to the spines making movement of the body possible (see diagram 6.2).
Diagram 6.2 - Cross section of a lumbar vertebre
The shape and size of the vertebrae of mammals vary from the neck to the tail. In the neck there are cervical vertebrae with the two top ones, the atlas and axis, being specialized to support the head and allow it to nod “Yes” and shake “No”. Thoracic vertebrae in the chest region have special surfaces against which the ribs move during breathing. Grazing animals like cows and giraffes that have to support weighty heads on long necks have extra large spines on their cervical and thoracic vertebrae for muscles to attach to. Lumbar vertebrae in the loin region are usually large strong vertebrae with prominent spines for the attachment of the large muscles of the lower back. The sacral vertebrae are usually fused into one solid bone called the sacrum that sits within the pelvic girdle. Finally there are a variable number of small bones in the tail called the coccygeal vertebrae (see diagram 6.3).
Diagram 6.3 - The regions of the vertebral column dik