It is important to read this question carefully, as it asks for the cells that form myelin sheaths around axons outside of the central nervous system. In essence, it is asking about the peripheral nervous system.

Schwann cells and oligodendrocytes both form myelin sheaths (a white, fatty substance) around axons, which act as electrical insulation and increase the speed of action potential conduction. Schwann cells perform this function for neurons in the peripheral nervous system (outside of the central nervous system), while oligodendrocytes myelinate neurons in the central nervous system.

Schwann cells insulate peripheral axons with myelin. Oligodendrocytes serve a similar purpose, but do so in the central nervous system, and not the peripheral system.

Schwann cells are used to myelinate single axons in the peripheral nervous system. Oligodendrocytes are the counterpart of Schwann cells that exist in the central nervous system, but are capable of myelinating multiple axons at once.

To answer this question, we must select an answer that is part of the peripheral nervous system. Grey matter and white matter only exist in the central nervous system (brain and spinal cord) and can be eliminated. Broca's area is located in the frontal lobe of the cerebrum and will contain oligodendrocytes instead of Schwann cells. The optic nerve and trigeminal nerve are two of the cranial nerves, C2 and CV respectively. The optic nerve is the only cranial nerve to be myelinated by oligodendrocytes. The trigeminal nerve will be myelinated by Schwann cells.

Schwann cells are responsible for producing myelin in the peripheral nervous system. These cells surround the axons with myelin sheaths, which increases the rate of signal transmission on axons. 

Oligodendrocytes are responsible for myelinating axons in the central nervous system. Dendrites are not myelinated.

Oligodendrocytes are cells that insulate axons in the central nervous system. They are capable of producing the myelin sheathes for several surrounding cells and are the counterparts of the Schwann cells, which are located in the peripheral nervous system. The central nervous system includes the brain and spinal cord. Oligodendrocytes are responsible for producing the white matter of the central nervous system. The frontal lobe is a region of the cerebrum and will contain myelin. The spinal cord contains distinct white matter and grey matter regions. Wernicke's area is located in the temporal lobe of the cerebrum, and will contain oligodendrocytes. The pons is located in the hindbrain, or brainstem, and will and will also contain oligodendrocytes.

The meninges are the layers of connective tissue that surround the central nervous system. They are made primarily of collagen and do not contain nerve fibers. Oligodendrocytes will not be found in the meninges.

Both oligodendrocytes and Schwann cells are responsible for myelinating axons in order to increase the transmission rate of signals between neurons. The primary difference is their location. Oligodendrocytes myelinate the central nervous system, while Schwann cells myelinate the peripheral nervous system. Oligodendrocytes are also capable of myelinating multiple axons, while Schwann cells can only myelinate one axon per cell.

Oligodendrocytes and Schwann cells both create myelin sheaths for axons, however, oligodendrocytes function in the central nervous system and Schwann cells function in the peripheral nervous system.

Myelin sheathes function in insulating the neuron, and allows for much faster propogation of the action potential due to saltatory conduction. Loss of the myelin sheath would slow conduction of signals down the neural axon.

Pain perception is conducted to free nerve endings known as nociceptors, which are not myelinated.

There are two types of cells responsible for the myelination of axons throughout the nervous system. Oligodendrocytes myelinate the axons of neurons in the central nervous system. Schwann cells myelinate neurons in the peripheral nervous system. This question is referring to a nerve in the elbow, which would be in the peripheral nervous system.

Astrocytes are a type of glial cell primarily found in the blood-brain barrier. Dendritic cells play a role in the adaptive immune response, and are not considered part of the nervous system.

Ependymal cells, which line cerebral cavities and the central canal, produce cerebrospinal fluid (CSF). CSF is a colorless liquid that protects the brain and spinal cord against injury.

Microglia protect the central nervous system from microbes and debris of injured cells. Astrocytes, located in the central nervous system, provide structural support for neurons in addition to many other tasks involving nutrient and ion regulation. Oligodrendrocytes produce the myelin sheath around the axons of the central nervous system. Satellite cells are not found in the central nervous system, and therefore cannot produce CSF.