$(document).ready(function() {
    SetMenu();
});

function SetMenu() {
    var nInfoModel = 84;
    var ModelNavigation = 28;
    var nElementModelNavigation = ($('#contentMenu > ul > li').length) - 1;
    var HeigthMenu = (ModelNavigation * nElementModelNavigation) + nInfoModel;
    $('#contentMenu').css({ 'height': HeigthMenu + 'px' }, 350);
}