Medullated

Medullated refers to the presence of a myelin sheath around a nerve fiber. It is a term used in neuroscience and histology to describe the process of myelination, or the formation of a fatty insulating sheath around the axons of nerve cells. This process is crucial for the proper functioning of the nervous system, as it increases the speed and efficiency of electrical signals along the nerve fibers.

Structure

Medullated nerve fibers are composed of an inner axon, an outer myelin sheath, and a thin layer of cytoplasm called the neurilemma. The myelin sheath is a thick, fatty layer that insulates the axon and increases the speed of nerve impulse transmission. The neurilemma, also known as the sheath of Schwann, is a thin layer of cytoplasm that surrounds the myelin sheath and aids in the regeneration of damaged nerve fibers.

Function

The primary function of medullated nerve fibers is to transmit electrical signals, or nerve impulses, rapidly and efficiently from one part of the body to another. The myelin sheath acts as an insulator, preventing the loss of electrical energy from the axon and increasing the speed of impulse transmission. This is particularly important in the peripheral nervous system, where nerve impulses often have to travel long distances.

Clinical significance

Abnormalities in the myelination process can lead to a variety of neurological disorders. For example, multiple sclerosis is a disease characterized by the loss of myelin in the central nervous system, leading to symptoms such as fatigue, difficulty walking, and problems with coordination. Similarly, Charcot-Marie-Tooth disease is a genetic disorder that affects the myelin sheath in the peripheral nervous system, causing muscle weakness and sensory loss.

See also

• Unmyelinated fiber
• Schwann cell
• Oligodendrocyte
• Ranvier's nodes

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