Individual appeals are heard by three-judge panels. According to 2009 statistics (the most recent available as of January 2011), there were 181 active seats allocated to the thirteen US Court of...
It depends on which court of appeals you are talking about. Typically, a panel of 3-5 judges hear appeals, but some states have more, and sometimes the court hears an appeal en banc.
In the US Court of Appeals Circuit Courts, a panel typically consists of three judges. On occasion, cases are heard "en banc," meaning most or all of the judges for the Circuit are present. The...