This is because of complete decussation
of the optic nerve fibers at the optic chiasm and then again between the pretectal nucleus and the parasympathetic nucleus of cranial nerve III.
The lack of peduncular decussation
often results in a superior vermian cleft.
Motor fiber decussation
may extend from obex to C1, and a high lesion in this LST can cause contralateral leg weakness (34).
Two sutures intersected the outside of the wound (just decussation
without the knot).
During development, decreased melanin synthesis in the retinal pigment epithelium results in foveal hypoplasia and dysregulation of adjacent retinal ganglion cells, and consequently, misrouted decussation
of the nerve fibres connecting the retina to the brain at the optic chiasm.
1) This appearance is a result of absence or hypoplasia of the cerebellar vermis, lack of normal dorsal decussation
and consequent enlargement of the superior cerebellar peduncles which follow a more horizontal course as they extend perpendicularly to the brainstem between the midbrain and the cerebellum.