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Neurological Assessment and Monitoring 419

TABLE 16.2 Neuroglia, their location and role as supporting nervous tissue

Type Location Main Function
Astrocytes CNS: The largest and most numerous ● Astrocytes are considered as important as
neuroglial cells in the brain and spinal the neuron in communication and brain
cord. regulation.
● They regulate communication, extracellular
ionic and chemical environments between
neurons.
● They respond to injury and have an
important role in cerebral oedema.

Ependymal cells CNS: Line the ventricular system of the ● Transport of CSF and brain homeostasis.
brain and central cord of the spinal ● Phagocytotic defence against pathogens.
canal. ● Store glycogen for brain tissue.

Microglia CNS: Located within the brain ● Wander between the peripheral immune
parenchyma behind the blood–brain system and the CNS as a defence to
barrier. infection.
● Displace synaptic input in injured neurons.

Oligodendrocytes CNS: Spiral around an axon to form a ● Responsible for the formation of myelin
multilayered lipoprotein coat in both sheaths surrounding axons.
the white and grey matter in the brain ● Oligodendrocytes wrap themselves around
and spinal cord. numerous axons at once.
PNS: Schwann cells are the supporting ● Schwann cells wrap themselves around
cells of the PNS. peripheral nerve axon.
● Unlike oligodendrocytes, a single Schwann
cell makes up a single segment of an axon’s
myelin sheath.

CSF = cerebral spinal fluid; CNS = central nervous system; PNS = peripheral nervous system.

information from the body and the delivery of motor The majority of the remaining cortical area is known as
commands. These occur in specific areas of the brain and the association cortex, where the processing of extensive
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can be mapped. Topographically, the cerebral cortex is and sophisticated neural information is performed. The
divided into areas of specialised functions, including the association areas are also sites of long-term memory, and
primary sensory areas for vision (occipital cortex), they control human functions such as language acqui-
hearing (temporal cortex), somatic sensation (postcen- sition, speech, musical ability, mathematical ability,
tral gyrus), and primary motor area (precentral gyrus). complex motor skills, abstract thought, symbolic thought,
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As shown in Figure 16.5, these well-defined areas com- and other cognitive functions. Association areas intercon-
prise only a small fraction of the surface of the cerebral nect and integrate information from the primary sensory
cortex. and motor areas via intra-hemispheric connections. The