THE THORACIC CAGE

The thoracic cage (rib cage) is the skeleton of the thoracic wall. It is formed by the 12 thoracic vertebrae, 12 pairs of ribs and associated costal cartilages and the sternum.
The thoracic cage takes the form of a domed bird cage with the horizontal bars formed by ribs and costal cartilages.

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It is supported by the vertical sternum or breastbone (anteriorly) and the 12 thoracic vertebrae (posteriorly).
The thoracic cage can also be described as an osteocartilaginous cage formed by the sternum, 12 pairs of ribs and costal cartilages, 12 thoracic vertebrae and the intervertebral (IV) discs interposed between them.

The thoracic cage, like skeletal tissue in most parts of the body, serves to support the thorax.
It also has several functions, such as:

1. protecting vital thoracic and abdominal internal organs from external forces
2. resisting the negative internal pressures generated by the elastic recoil of the lungs and respiration-induced movements
3. providing attachment for and supporting the weight of the upper limbs
4. providing the anchoring attachment (origin) of many of the muscles that move and maintain the position of the upper limbs relative to the trunk and also support for the shoulder girdle (clavicle and scapula).

Hemopoiesis: Red bone marrow of ribs, sternum and center of thoracic vertebrae (make red blood cells, white blood cells and platelets)
Uses intercostal muscles to lift and depress the thorax during breathing
Together with the skin and associated fascia and muscles, the rib cage makes up the thoracic wall and provides attachments for the muscles of the neck, thorax, upper abdomen, and back.