Question

a) what type of rib does the arrow point to? b) which bones does it articulate with? human thoracic cage with arrow pointing to the last bottom rib. floating rib, thoracic vertebra false rib, thoracic vertebra and costal cartilage of rib above true rib, thoracic vertebra and sternum

Explanation:

A. Floating ribs are the last two pairs of ribs (11th and 12th) that do not attach anteriorly to the sternum or costal cartilages of other ribs. The arrow points to the last bottom rib which is a floating rib.
B. Floating ribs articulate only with the thoracic vertebrae posteriorly.

Answer:

A. Floating rib
B. Thoracic vertebra