var ImgAbierta = new Image();
ImgAbierta.src = "img/open.gif";
var ImgCerrada = new Image();
ImgCerrada.src = "img/closed.gif";

function MostrarRama(rama){
	var objRama = document.getElementById(rama).style;
	if(objRama.display == "block")
		objRama.display = "none";
	else
		objRama.display = "block";
}