The human vertebrae are divided into differentiated groups. The seven most superior of them are the vertebrae called the cervical vertebrae. The first cervical vertebra is the atlas. The second vertebra is called the axis.

Inferior to the cervical vertebrae are twelve thoracic vertebrae. There is one rib connected to each thoracic vertebrae, making 12 pairs of ribs. Most of the rib pairs come together ventrally and join a flat bone called the sternum.

The first pairs or ribs are short. All seven pairs join the sternum directly and are sometimes called the «true ribs». Pairs 8, 9, 10 are «false ribs». The eleventh and twelfth pairs of ribs are the «floating ribs».

Inferior to the thoracic vertebrae are five lumbar vertebrae. The lumbar vertebrae are the largest and the heaviest of the spinal column. Inferior to the lumbar vertebrae are five sacral vertebrae forming a strong bone in adults. The most inferior group of vertebrae are four small vertebrae forming together the соссуx.

The vertebral column is not made up of bone alone. It also has cartilages.

skeleton – скелет

make up – составлять

weight – вес

trunk – туловище

vertebrae – позвоночник

thoracic cavity – грудная клетка

pelvic – тазовый

cervical – шейный

atlas – 1 шейный позвонок

sternum – грудина

mainly – главным образом

axis – ось

spinal column – позвоночник

inferior – нижний

rib – ребро

pair – пара

sacral – сакральный

соссуx – копчик

floating – плавающий

forming – формирующий

cartilage – хрящ

lumbar – поясничный

adult – взрослый

11. Muscles

Muscles are the active part of the motor apparatus; their contraction produces various movements.