The board of trustees shall designate a medical board to be composed of three (3) physicians not eligible to participate in the retirement system. If required, other physicians may be employed to report on special cases. The medical board shall arrange for and pass upon all medical examinations required under the provisions of this chapter, and shall investigate all essential statements and certificates by or on behalf of a member in connection with an application for disability retirement, and shall report in writing to the board of trustees its conclusion and recommendations upon all the matters referred to it. Compensation for services of the members of the medical board shall be determined by the board of trustees.