axial  
adjective  specialized uk/ˈæk.si.əl/ us/ˈæk.si.əl/
  (OF LINE)     
  mathematics 轴的;轴线的
relating to or around a real or imaginary straight line going through the centre of an object that is spinning, or a line that divides a symmetrical shape into two equal halves
   (IN THE BODY)       
 anatomy (身体)中心线的
relating to an imaginary line through the centre of the body
  anatomy 枢椎的,第二颈椎的
relating to the axis (= the second of the small bones in the neck that form the spine and support the skull)