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3. • 31 pairs of spinal nerves originating from the spinal cord
• According to the region they are divided into;
– Cervical nerves: 8 pairs
– Thoracic nerves: 12 pairs
– Lumbar nerves: 5 pairs
– Sacral nerves: 5 pairs
– Coccygeal nerve: 1 pair

6. • 12 pairs of cranial nerves originating from the nuclei
present in the brain.
• The nerves are sensory, motor or mixed.

7. • Their names & numbers are as follows;
– Olfactory (I): Sensory
– Optic (II) : Sensory
– Oculomotor (III): Motor
– Trochlear (IV): Motor
– Trigeminal (V): Mixed
– Abducent (VI): Motor
– Facial (VII): Mixed
– Vestibulocochlear (auditory) (VIII): Sensory
– Glossopharyngeal (IX): Mixed
– Vagus (X): Mixed
– Accessory (XI): Motor
– Hypoglossal (XII): Motor

8. • Olfactory nerves:
• Sensory type of nerve
• Originates in the olfactory lobe i.e. root of nose &
terminates in the temporal lobe of cerebrum.
• Associated with sense of smell.
• Optic nerves:
• Sensory type of nerve
• Originates in the retina of eyes & terminates in the occipital
lobe of cerebrum.
• Related with sense of vision

9. • Oculomotor nerves:
• Mixed type of nerve that originates in the mid-brain.
• Efferent (motor) portion: It innervates skeletal muscles
that moves the eyeball & innervates smooth muscles
that constrict pupil.
• Afferent (sensory) portion: It is related to movement of
eyeball & regulating the size of pupil.

10. • Trochlear nerve:
• Mixed type of nerve & originates in midbrain
• Smallest of the 12 cranial nerves
• Motor portion: Related to movement of eyeball
• Sensory portion: Carries information from eye to
midbrain

11. • Trigeminal nerve:
• Mixed type of nerve
• Largest among all the cranial nerves
• Motor portion: Originates from pons & innervates the
muscles of mastication (skeletal chewing muscles)
• Motor function: Chewing

12. • Sensory portion consists of 3 branches;
• Ophthalmic nerve: Contains nerves from eyelids, eyeball,
lacrimal glands, nasal cavity, nose & forehead.
• Maxillary nerve: Contains nerve from the mucosa of
nose, pharynx, teeth, upper lip & lower eyelid.
• Mandibular nerve: Contains nerve from tongue, teeth,
skin, mandible & cheek.
• Sensory function: Conveys impulses for touch, pain &
temperature.

13. • Abducens nerve:
• Mixed type of nerve & originates in the pons
• Motor portion: Innervates the skeletal muscles that
moves eyeball.
• Sensory portion: It is related to movement of eyeball &
muscles sense (proprioception)
• Motor function: Movement of eyeball
• Sensory function: Proprioception (body's ability to sense
movement, action & location)

14. • Facial nerve:
• Mixed type of nerve
• Motor nerve: Originates from pons & innervates skeletal
muscle of face, nose, palate, lacrimal & salivary gland.
• Sensory nerve: Transmits information from taste buds in
the tongue & mouth.
• Motor function: Facial expression
• Sensory function: Taste & Proprioception

15. • Vestibulocochlear nerve:
• Sensory type of nerve
• It consists of two nerves,
• Vestibular nerve: Arises from semicircular canals of inner
ear & conveys impulses to the cerebellum.
• They are associated with maintenance of posture &
balance.
• Cochlear nerve: Originates in the spiral organ of the
inner ear & conveys impulses to the hearing area of
cerebrum.
• It is responsible for hearing.

16. • Glossopharyngeal nerve:
• Mixed type of nerve
• Motor nerves: Originate from medulla oblongata &
innervate the tongue & pharynx.
• Motor function: Movement of pharynx during
swallowing & speech
• Sensory nerves: Originate from salivary glands &
terminates in medulla oblongata
• Sensory function: Taste, touch, pain & temperature
sensations, monitoring of blood pressure

17. • Vagus nerve:
• Mixed type of nerve
• Motor fibers: Originates in the medulla & innervates the
smooth muscles of pharynx, larynx, trachea, heart
esophagus, stomach, intestine, pancreas, gall bladder,
bile duct, spleen, kidney, ureter, blood vessels in thoracic
& abdominal cavities.
• Motor function: Swallowing, coughing & voice
production.
• Sensory fibers: Convey impulses from same organs to
brain.
• Sensory function: Taste, touch, pain, temperature
regulation & monitoring of blood pressure.

18. • Accessory nerve:
• Motor type of nerve.
• It originates from medulla oblongata & innervates the
muscles of pharynx & skeletal muscle of neck.
• Motor function: Swallowing & movement of head &
shoulders.

19. • Hypoglossal nerve:
• Motor type of nerve
• It originates in the medulla & innervates the muscle of
tongue.
• Motor function: Movement of tongue during speech &
swallowing.

20. • The peripheral nervous system consists of somatic
nervous system (SNS) and autonomic nervous system
(ANS).
• Somatic nervous system consists of sensory neuron &
motor neuron.
• Sensory neurons convey message from periphery to the
CNS.
• These include sensations of pain, temperature, taste,
smell, hearing & vision, etc.
• Motor neurons conveys information from brain to
periphery.

21. • The autonomic nervous system which controls the
autonomic function of the body i.e. initiates in the brain.
• The effects of autonomic activity are rapid and effector
organs are;
• Smooth muscle i.e. changes in bronchioles & blood
vessels diameter.
• Cardiac muscle i.e. changes in rate & force of the
heartbeat.
• Glands i.e. increase or decrease in GIT secretions.

22. • Consists of 2 types of neurons
– Autonomic sensory neuron
– Autonomic motor neuron
• Autonomic sensory neuron (afferent):
• These neurons are associated with sensory receptors
located in blood vessels, visceral organs & muscles.
• Autonomic motor neuron (efferent):
• These neurons regulates visceral activities by either
increase or decrease ongoing activities in the effector
tissues (cardiac muscle, smooth muscles or glands)

23. • E.g. Change in pupil diameter, dilation or constriction of
blood vessels, adjusting the heart rate & force of
contraction.
• The autonomic nervous system is separated into two
divisions.
– Sympathetic (Thoracolumbar outflow) division
– Parasympathetic (Carniosacral outflow) division
• Two divisions have both structural & functional
differences.
• They normally work in opposite manner.
• Each division has two motor neurons, autonomic ganglia
and effector organs.

24. • These are;
– Pre-ganglionic neurons
– Post-ganglionic neurons
• The autonomic ganglion is the collection of cell bodies
outside the CNS.
• The motor neurons which lies before the ganglion is
called as preganglionic neuron.
• The myelinated axon is called as preganglionic fiber.
• The motor neuron which lies after the ganglion and
terminates in the effector organ called as postganglionic
neuron.
• The myelinated axon is called as postganglionic fibers.

28. • It is called as thoracolumbar division.
• It consists of two types of autonomic ganglia.
– Sympathetic trunk ganglia
– Prevertebral ganglia
• Sympathetic trunk ganglia:
• These ganglia lie in a vertical row on either side of
vertebral column.
• These lies close to spinal cord & therefore the
preganglionic fibers are short.

29. • Prevertebral ganglia:
• These are 3 types of ganglion;
– Coeliac ganglion
– Superior mesenteric ganglion
– Inferior mesenteric ganglion
• These are the ganglion situated close to the abdominal
cavity.

31. • The preganglionic nerve fibers are shorter.
• The postganglionic nerve fibers are longer.
• The preganglionic neurotransmitter is acetylcholine.
• Most of the postganglionic nerve fibers are adrenergic.
• The targeted receptors are mostly adrenergic.
• Distributed throughout the body.

32. • It is called as craniosacral division.
• It contains parasympathetic ganglia.
• The parasympathetic ganglia are dispersed.
• The ganglia are near or within the wall of the effector
organs.
• The preganglionic nerve fibers are large.
• The post ganglionic nerve fibers are shorter.

33. • The preganglionic nerve fibers are acetylcholine.
• Most of the postganglionic nerve fibers are cholinergic.
• The targeted receptors are mostly cholinergic.
• The distribution is limited, particularly to heart, viscera of
thorax, abdomen & pelvis.