Mo. Rev. Stat. § 472.020
The probate division of the circuit court may hear and determine all matters pertaining to probate business, to granting letters testamentary and of administration, the appointment of guardians and conservators of minors and incapacitated and disabled persons, settling the accounts of personal representatives and conservators, and the sale or leasing of lands by personal representatives and conservators, including jurisdiction of the construction of wills as an incident to the administration of estates, of the determination of heirship, of the administration of testamentary and inter vivos trusts, of disability and incapacity proceedings as provided by law and of such other probate business as may be prescribed by law.
§ 472.020, RSMo
RSMo 1939 § 2437, A.L. 1955 p. 385 § 3, A.L. 1978 H.B. 1634, A.L. 1983 S.B. 44 & 45