A Doctor of Chiropractic, for all legal purposes, shall be considered an expert in his field and, when properly qualified, may testify in a court of law as to:
(1) The etiology, diagnosis, prognosis, and disability, including anatomical, neurological, physiological, and pathological considerations within the scope of chiropractic, as defined in G.S. 90-151; and
(2) The physiological dynamics of contiguous spinal structures which can cause neurological disturbances, the chiropractic procedure preparatory to, and complementary to the correction thereof, by an adjustment of the articulations of the vertebral column and other articulations.