Myelin sheath is present around the

Options

A. Non- medullated nerve fibre
B. Medullated nerve fibre
C. Medullated and non-medullated nerve fibres
D. Muscle fibres.

Answer

**Step-by-Step Text Solution:**

1. **Understanding Myelin Sheath**: The myelin sheath is a protective covering that surrounds certain types of nerve fibers, specifically the axons of neurons.

2. **Composition of Myelin Sheath**: The myelin sheath is composed of a modified plasma membrane that is greatly extended and wrapped around the axon in a spiral manner.

3. **Origin of Myelin Sheath**: In the peripheral nervous system (PNS), the myelin sheath is formed by Schwann cells. In the central nervous system (CNS), it is formed by oligodendroglial cells.

4. **Function of Myelin Sheath**: The primary function of the myelin sheath is to insulate the axon, which helps in the rapid transmission of electrical impulses along the nerve fiber.

5. **Conclusion**: Therefore, the myelin sheath is present around the axons of neurons in both the peripheral and central nervous systems.

**Final Answer**: The myelin sheath is present around the axons of neurons.

---