(a) The creation of unincorporated islands as described in paragraph (1), (2), or (3) of this subsection shall be prohibited:

(1) Annexation or deannexation which would result in the creation of an unincorporated area with its aggregate external boundaries abutting the annexing municipality;

(2) Annexation or deannexation which would result in the creation of an unincorporated area with its aggregate external boundaries abutting any combination of the annexing municipality and one or more other municipalities; or

(3) Annexation or deannexation which would result in the creation of an unincorporated area to which the county would have no reasonable means of physical access for the provision of services otherwise provided by the county governing authority solely to the unincorporated area of the county.

(b) When requested by resolution of the county governing authority, a municipality is authorized to provide any service or exercise any function within an unincorporated island. Such authority shall be in addition to any other authority of the municipality to provide extraterritorial services or functions. For purposes of this subsection, "unincorporated island" shall have the same meaning as contained in paragraph (3) of Code Section 36-36-90.