As the primary axons reach the caudal medulla, they leave their respective fasiculi and enter and synapse on secondary neurons within the nucleus gracilis and the nucleus cuneatus, respectively.

• 一级感觉神经元的轴突会伸延至延髓的尾部，且拥有细长细胞核或楔形细胞核的神经元会分别透过进入或于二级感觉神经元及轴突间形成突触而离开延髓的尾部。