There are vertebrae in the cervical part of the spine. 2. There are ... vertebrae in the thoracic part of the spine.

1. There are seven vertebrae in the cervical part of the spine. 2. There are twelve vertebrae in the thoracic part of the spine. 3. There are five vertebrae in the lumbar part of the spine. 4. There are  five vertebrae in the sacral part of the spine. In general, the spinal cord consists of thirty three vertebrae. 

Please, note that some nouns in English (especially of Greek and Latin origin) form their plural form not only by adding - s at the end (though this form is also rarely used) but by keeping their original plural form in Greek or Latin. For example: vertebra (singular) -vertebrae (plural), phenomenon (singular) - phenomena (plural)