PHP多维数组，仅通过1个foreach循环获取指定数据

I have two-dimensional array $id[][] and i'm accessing data by using two foreach loops

    foreach ($id as $index=>$val)
{

    foreach ($val as $ind=>$id_val)
{
...

}

}

but how to do that without first foreach, so looping process would start and end on specified index, for example $id[1]["and now looping with foreach second dimension"]. Number of records on second dimension may differ.

How to achieve that, like in other programming languages with just simply putting index of 1st dimension and beginning loopiing on second only ?