Sure it is. There are roads that cross. Avenida 4 de Julio in Panama City is one. The Centennial Bridge on the Via Puente Centenario near Paraiso is another.
Panama canal is passable. However the Darien Gap to the south is not survivable for 99% of people.
People who were extremely physically fit and professionally equipped have gone through on foot. However, these days the narcocartels control the jungle and I dont think anyone even attempts it.