Answer:
Imagine standing and crossing your arms (i.e. so that your right hand touches your left thigh and your left hand touches your right thigh). This would be considered the fiber direction of your External obliques which are the most superficial abdominal muscles. Deep to the external obliques are your internal oblique muscles. Your internal obliques run mostly perpendicular to your external obliques (i.e. opposite direction). The next layer of the abdominal muscles are the transverse abdominals whose fiber direction is parallel (horizontal) to the ground (when standing).
Hope this helps.