The facial colliculus is an elevation on the floor of the fourth ventricle and is not formed by the facial nucleus, but by the fibers of the facial nerve arching backwards around the abducent nucleus before turning forwards once more in the caudal pons.
A lesion involving the facial colliculus is, therefore, likely to result in facial colliculus syndrome by involving:
- abducens nerve (CN VI) nucleus
- facial nerve (CN VII) fibers at the genu
- medial longitudinal fasciculus
The facial colliculus may be symmetrically absent in horizontal gaze palsy with progressive scoliosis, giving a tent shape to the floor of the fourth ventricle.