[The variations in the origin of cranial nerves III, IV and VI].

In 100 human brains the spot and the mode of emergence of the 3rd, 4th and 6th cranial nerves where investigated. In analogy to spinal nerves a fusion of Fila radicularia to roots and of roots to the complete nerves could be described. For the 3rd nerve 3 types had to be distinguished: in 21% there was only 1 root, in 71% there were 2 roots, one of which emerged from the Sulcus n. oculomotorii and the other from the Crus cerebri and in 8% 2 roots formed a tong embracing the medical part of the Crus cerebri. The number of rootlets of the 4th nerve varied from 1 to 5; most frequently--in 45%--there were 2. The 6th nerve shows 3 types: in 46% 1 root, in 47% 2 roots and in 7% 3 roots.