Vertebral column

The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate, in which the notochord (a flexible rod of uniform composition) found in all chordates has been replaced by a segmented series of bones (vertebrae) separated by intervertebral discs. The vertebral column houses the spinal canal, a cavity that encloses and protects the spinal cord.

The number of vertebrae differ between species. Here are different vertebral formulae (note that all mammals have seven cervical vertebrae):

• Dogs: C7 T13 L7 S3 Cd20

• Cats: C7 T13 L7 S3 Ca18-23

• Horses: C7 T18 L6 S5 Cd15-21

• Bovine: C7 T13 L6 S5 Cd18-20

• Ovine: C7 T13 L6-7 S4 Cd16-20

• Pigs: C7 T14-15 L6 S4 Cd20-23