Composition and Functions:
Divided into two parts (CNS and PNS)
Responsible to perform:
1. receives stimuli from receptors
2. transmits information to effectors that
respond to stimulation.
3. Regulates behavior by integrating
incoming sensory information with stored
4. translating that into action by way of
• Includes billions of nerve cells (NEURONS)
Neuron is the living nerve
cell. It performs the
specific function of the
system. In this instance, is
to transmit nerve
Neuron contains the
CELL BODY - where nucleus and other
organelles are located.
• Dendrite - conduct nerve impulses
toward the cell body.
• Axon - conducts nerve impulses away
from the cell body. It is covered by
tightly packed Schwann cells
containing myelin as insulator
Types as to
1. SENSORY NEURON -
transmit impulses from
sensory receptors of
the sense organ to
nerve center (CNS).
2. MOTOR NEURON -
transmit impulses form
the nerve center to the
effectors (muscles or
3. ADJUSTOR OR
- connects sensory
and motor neurons;
located in nerve
center, also called
• Composed of actively dividing cells
supporting the neurons of the nervous
There are several types of neuroglia based on
1. ASTROCYTES - connect neurons and
2. MICROGLIA - dispose dead cells, bacteria,
3. EPENDYMAL - line the fluid- filled cavities
of CNS for protection.
4. OLIGODENDROCYTES - form the myelin
sheath around the fibers.
5. SCHWANN CELLS and SATELLITE CELLS
• Dorsal & Ventral nerves arises from spinal
• Dorsal roots has GANGLIONS
• Dorsal & ventral roots connect spinal
nerves to spinal cord
• Spinal nerves through ramus
branches of spinal nerves
1. Dorsal ramus - supplies epaxial muscles
and skin, dorsal part
2. Ventral ramus - supplies hypaxial muscles
and skin, ventral part
Functional types of neurons in
• Somatic afferent - sensory from general
cutaneous receptors and proprioreceptors
• Somatic efferent - motor to skeletal muscles
• Visceral afferent - sensory from receptors in
• Visceral efferent - motor to smooth, cardiac
muscles and glands
Cranial nerves are classified in one of three
1) In series with dorsal roots of spinal nerves
join the brainstem at a lateral (not ventral)
level include mixed nerves - sensory and
motor neurons includes nerves 0, V, VII,
IX, X, XI
2) In series with ventral spinal nerves join
the brainstem at the ventral level contain
somatic motor fibers, and supply
branchiometric muscles, (branchiometric
nerves) includes nerves III, IV, VI, XII
3) No counterpart in spinal series because its
nerves serve structures that are peculiar
to the head (nose, eye, ear, lateral line
system)sensory fibers includes nerves I, II,
VII, VIII, IX
• Terminal nerve: part of chemosensory
system, such as for responding to olfactory
pheromones. Absent in cyclostomes, birds,
• Olfactory: runs from the olfactory
epithelium to the olfactory bulb of the
• Optic: runs from the eye to the brain.
Ganglion cells in the retina may cross over
under the brain at the optic chiasma.
• Oculomotor: supplies external ocular
muscles (dorsal rectus, medial rectus,
ventral rectus, ventral oblique). Has ciliary
branch that passes to muscles of the iris
and ciliary muscles.
Cranial Nerves (cont)
• Facial:Serves muscles responsible
for facial expression.
• Statoacoustic or vestibulocochlear
or auditory: serves the inner ear.
The anterior branch serves the
organ of equilibrium, while the
posterior branch is responsible for
equilibrium and hearing.I
• Glossopharyngeal: associated with
pharynx, taste buds and salivary
• Vagus: contains four branches that
supply the branchiometric muscles
of the 4 - 7 visceral arches (or their
• Accessory - spinal accessory nerves
• Hypoglossal: serves hypobranchial
muscles of the throat and tongue
• Trochlear: supplies the
dorsal oblique muscle of
• Trigeminal: has three
(serves the head region),
maxillary (serves the upper
jaw) and mandibular
(serves the lower jaw).
Where the branches
intersect and cell bodies
are found is called the
• Abducens: supplies the
lateral oblique muscle of
Development Structure and Evolution
• Located in vertebral canal,
anatomical beginning is the foramen
magnum of the skull.
• Length varies.
WITH TAIL - it extends to the caudal
end of the vertebral column.
WITHOUT TAIL - it extens to about
the lumbar region of the vertebral
Gray matter - nerve cell bodies.
White matter - nerve cell processes.
• Meninges - membranes which surround
the brain and spinal cord.
Pia mater - innermost membrane
Arachnoid mater – Middle membrane
Dura mater - Outermost layer
• Cerebrospinal Fluid - Is secreted by the
choroid plexi. It protects the brain and
cushions it from the skull.
• Blood-brain barrier - Two epithelia
which controls the flow of solutes from
blood to brain. Prezi :