Pleural cavity: the cavity in the thorax that contains the lungs. Source: WordNet 2.1. Pleural cavity: cavity within the thoracic cavity consisting of the space between the parietal and visceral pleura; normally contains a capillary layer of serous fluid that lubricates the pleural surfaces.
Middle Class Average Income Range: $36,000 â $57,657. On a narrow view, a middle class family is said to have a mean average household income of $46,829 on a yearly basis. The numbers reflected on the 2010 Census showed that middle class average yearly income range from $36,000 â $57,657. Such figures fall on the third quintile.
This would make the middle class income range $25,117 to $100,466. MIT economist Frank Levy believes that those in the middle class have enough money to afford the basic building blocks of a good life, including a house, a car and money to pay necessary bills.