I've noted some details, let me explain:

---

1. [CSS Selectors][1]. jQuery allows you to use them too:

    $("[id^='content-wrap']") --> will select all elements which id starts with 'content-wrap'

---

2. [Substring][2] is an available method of JavaScript:

    var number = "navItem15".substring(7);
    // will return what is after position 7.. 
    // resulting the number "15"

---

3. To start your menu with the first position. [This is][3] the best way:

    (function(){
        $("#navItem1").trigger("click");
    })();
    // using this approach, you won't need copy your code into a function as you did
    // this approach triggers the "click" event in the first menu automatically

---

Well, hope you got it!

Nice coding!


  [1]: http://www.w3schools.com/cssref/css_selectors.asp
  [2]: https://developer.mozilla.org/pt-BR/docs/Web/JavaScript/Reference/Global_Objects/String/substring
  [3]: http://jsfiddle.net/VQtwa/22/