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.
Middle Class Income for a Family. The annual average income for a middle class family of four is approximately $70, 354. This is based on a 2006 report by the U.S. Census for a family of four.This figure is in the middle of the range of incomes for this section of the population. The median income during this time for all households was $48,561.lthough many households feel that they are middle class, a 2011 Census report shows that 46.2 million people live in poverty. In the 2000s, the middle class took a hit. From 2000 to 2010, income levels for those in the middle class decreased by 7 percent.