Ullah M
J Anat. 1978 Feb;125(Pt 2):377-86.
The motor fibres of the phrenic nerve arise in the cervical portion of the spinal cord from a group of lower motor neuron cell bodies called the 'phrenic nucleus'. The phrenic nucleus of the rabbit has been located by cutting the right phrenic nerve (phrenicotomy) in the neck and observing retrograde degeneration (chromatolysis) in the cells of the ventral grey horn of the spinal cord 2-4 weeks later. The phrenic nucleus in the rabbit was found to extend from the fourth to the sixth cervical segment. It lay in the caudal half to three fourths of the fourth, the whole of the fifth and the cranial half to two thirds of the sixth segment. The phrenic nucleus in the rabbit is a longitudinal column of cells lying between the ventromedial and the ventrolateral columns of the ventral grey horn of the spinal cord. In the fourth and fifth cervical segments, the phrenic nucleus of the rabbit is dorso-medial to the ventrolateral column and dorsolateral to the ventromedial column. In the sixth segment it is dorsomedial to the ventrolateral column but lateral to the ventromedial column. The total number of chromatolysed cells found in the right phrenic nucleus (after right phrenicotomy in the neck) varied between 1496 and 1754. The chromatolysed cells had a peculiar and characteristic orientation in that in a frontal section they appeared longer than broad with their long axes almost parallel ti the longitudinal axis of the spinal cord.
膈神经的运动纤维起源于脊髓颈部一群称为“膈核”的下运动神经元细胞体。通过在颈部切断兔的右侧膈神经（膈神经切断术），并在2 - 4周后观察脊髓腹侧灰质角细胞中的逆行性变性（染色质溶解），确定了兔的膈核位置。发现兔的膈核从第四颈椎节段延伸至第六颈椎节段。它位于第四颈椎节段尾侧的一半至四分之三、整个第五颈椎节段以及第六颈椎节段头侧的一半至三分之二处。兔的膈核是位于脊髓腹侧灰质角腹内侧柱和腹外侧柱之间的一列纵向细胞。在第四和第五颈椎节段，兔的膈核位于腹外侧柱的背内侧和腹内侧柱的背外侧。在第六颈椎节段，它位于腹外侧柱的背内侧但在腹内侧柱的外侧。在右侧膈核（颈部右侧膈神经切断术后）中发现的染色质溶解细胞总数在1496至1754个之间。染色质溶解细胞具有独特的特征性取向，即在额状切面上，它们看起来长大于宽，其长轴几乎与脊髓的纵轴平行。
