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.
Robert Reich, a professor of Public Policy at the University of California-Berkeley and former Secretary of Labor, has suggested the middle class be defined as households making 50 percent higher and lower than the median, which would mean the average middle class annual income is $25,500 to $76,500.f you're in the middle of the middle, however â not lower or upper-middle class â that would be an income range between $39,764 and $64,582, says Aaron Pacitti, an assistant professor of economics at Siena College in Loudonville, N.Y.