In holoprosencephaly  the hemispheres of the cerebrum or part of it are not aligned on the left and right side but  on the frontal and occipital side of the skull, and  usually remains very small. According to the axial twist hypothesis, this represents an extreme case of Yakovlevian torque, and may occur when the cerebrum does not turn during early embryology. Cephalopagus or janiceps twins are conjoined twins which are born with two faces, one on either side of the head. These twins have two brains and two spinal chords, but these are located on the left and the right side of the body. According to the axial twist hypothesis, the two nervous systems could not turn due to the complex configuration of the body and therefore remained on either side.
In holoprosencephaly , the hemispheres of the cerebrum or part of it are not aligned on the left and right side but only on the frontal and occipital sides of the skull, and the head usually remains very small. According to the axial twist hypothesis, this represents an extreme case of Yakovlevian torque, and may occur when the cerebrum does not turn during early embryology. Cephalopagus or janiceps twins are conjoined twins who are born with two faces, one on either side of the head. These twins have two brains and two spinal chords, but these are located on the left and the right side of the body. According to the axial twist hypothesis, the two nervous systems could not turn due to the complex configuration of the body and therefore remained on either side.
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