This muscle, although not important functionally, is important from a surgical point of view.  The medial borders on the anterior aspect of the vertebral body allow the surgeon to determine where the midline is.  It is much more reliable than other local landmarks.

Pre-vertebral Fascia
This is a plane of surgical importance.  It is attached to the base of the skull and extends over the pre-vertebral muscles (longus capitis, rectus capitis and longus colli) to attach distally at T4, just beyond the longus colli muscle.  This forms a plane down which infections can tract.  Thus cervical infections can give rise to mediastinal abscesses.