Sheath of schwann cell containing cytoplasm and nucleus that encloses myelin is called

Neurilemma

Explanation:

Schwann cells are the neuroglia that produces myelin sheaths. There is a formation of multiple layers of the glial plasma membrane around axons. The cytoplasm and nucleus of Schwann cells from the outermost layer while the inner part has multiple layers of the Schwann cell membrane. The outer nucleated cytoplasmic layer of the Schwann cell that encloses the myelin sheath is called neurolemma. It is found only around axons in the PNS. Its function is to serve in the regeneration of injured axons by the formation of a regeneration tube.