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Peripheral Nervous System

• Cranial Nerves , Autonomic
nervous System ( sympathetic ,
Parasympathetic systems )
Peripheral Nervous System
Group Members
• Rida Sabih
• Mehwish Ali
• Zaira Kanwal
• Iqra Rasool
What is peripheral nervous System (PNS) ?
▪ encompasses nerves outside the brain and spinal cord
▪ signals from the brain and spinal cord are relayed to the periphery by motor nerves, to
tell the body to move or to conduct resting functions (like breathing, salivating and
▪ Nerves of PNS are divided into three types :
1. Sensory Nerves
2. Motor Nerves
3. Mixed nerves ( Both sensory and motor Neurons)
Based on
the type
▪ Types of nerves in PNS based on the direction of information flow :
1. Afferent Nerves :
-Bring information towards Central Nervous System
-They are sensory neurons and have the role of receiving sensory input
- Brings information to the CNS about the state of the internal organs (homeostatis )
2. Efferent Nerves :
- Moves away from Central Nervous System .
- Takes signals from the CNS to the organs.
▪ These nerves , collectively form the Somatic Nervous System , which is considered a part of the
PNS like Autonomic Nervous System.
▪ There are 43 segments of nerves in the human body. With each segment, there is a pair of sensory
and motor nerves. In the body, 31 segments of nerves are in the spinal cord and 12 are in the brain
▪ Besides these, thousands of association nerves are also present in the body.
▪ Thus the somatic nervous system consists of two parts:
 Spinal nerves: They are peripheral nerves that carry sensory information into and motor commands
out of the spinal cord.
 Cranial nerves: They are the nerve fibers that carry information into and out of the brain stem.
They include smell, vision, eye, eye muscles, mouth, taste, ear, neck, shoulders, and tongue.
 Function :
▪ The somatic nervous system controls all voluntary muscular systems within the body, and the
process of voluntary reflex arcs.
What are cranial nerves and what is their function ?
▪ cranial nerves are pairs of nerves that connect your brain to different parts of your head,
neck, and trunk.
▪ There are 12 of them, each named for their function or structure.
▪ Each nerve also has a corresponding Roman numeral between I and XII. This is based off
their location from front to back. For example, your olfactory nerve is closest to the front
of your head, so it’s designated as I.
▪ Their functions are usually categorized as being either sensory or motor. Sensory nerves
are involved with your senses, such as smell, hearing, and touch. Motor nerves control the
movement and function of muscles or glands.
▪ I. Olfactory nerve
▪ The olfactory nerve transmits sensory information to your brain regarding smells that
you encounter.
▪ II. Optic nerve
▪ The optic nerve is the sensory nerve that involves vision
▪ III. Oculomotor nerve
▪ The oculomotor nerve has two different motor functions: muscle function and pupil
▪ Muscle function. Your oculomotor nerve provides motor function to four of the six
muscles around your eyes. These muscles help your eyes move and focus on objects.
▪ Pupil response. It also helps to control the size of your pupil as it responds to light
▪ IV. Trochlear nerve
▪ The trochlear nerve controls your superior oblique muscle. This is the muscle that’s
responsible for downward, outward, and inward eye movements.
▪ V. Trigeminal nerve
▪ The trigeminal nerve is the largest of your cranial nerves and has both sensory and motor
▪ The trigeminal nerve has three divisions, which are:
▪ Ophthalmic. The ophthalmic division sends sensory information from the upper part of
your face, including your forehead, scalp, and upper eyelids.
▪ Maxillary. This division communicates sensory information from the middle part of your
face, including your cheeks, upper lip, and nasal cavity.
▪ Mandibular. The mandibular division has both a sensory and a motor function. It sends
sensory information from your ears, lower lip, and chin. It also controls the movement of
muscles within your jaw and ear
▪ VI. Abducens nerve
▪ The abducens nerve controls another muscle that’s associated with eye movement, called
the lateral rectus muscle. This muscle is involved in outward eye movement. For
example, you would use it to look to the side.
▪ VII. Facial nerve
▪ The facial nerve provides both sensory and motor functions, including:
▪ moving muscles used for facial expressions as well as some muscles in your jaw
▪ providing a sense of taste for most of your tongue
▪ supplying glands in your head or neck area, such as salivary glands and tear-producing
▪ communicating sensations from the outer parts of your ear
▪ VIII. Vestibulocochlear nerve
▪ Your vestibulocochlear nerve has sensory functions involving hearing and balance. It
consists of two parts, the cochlear portion and vestibular portion:
▪ Cochlear portion. Specialized cells within your ear detect vibrations from sound based
off of the sound’s loudness and pitch. This generates nerve impulses that are transmitted
to the cochlear nerve.
▪ Vestibular portion. Another set of special cells in this portion can track both linear and
rotational movements of your head. This information is transmitted to the vestibular nerve
and used to adjust your balance and equilibrium.
▪ IX. Glossopharyngeal nerve
▪ The glossopharyngeal nerve has both motor and sensory functions, including:
▪ sending sensory information from your sinuses, the back of your throat, parts of your
inner ear, and the back part of your tongue
▪ providing a sense of taste for the back part of your tongue
▪ stimulating voluntary movement of a muscle in the back of your throat called the
▪ X. Vagus nerve
▪ The vagus nerve is a very diverse nerve. It has both sensory and motor functions,
 communicating sensation information from your ear canal and parts of your throat
 sending sensory information from organs in your chest and trunk, such as your heart
and intestines
 allowing motor control of muscles in your throat
 stimulating the muscles of organs in your chest and trunk, including those that move
food through your digestive tract (peristalsis)
 providing a sense of taste near the root of your tongue
▪ XI. Accessory nerve
▪ Your accessory nerve is a motor nerve that controls the muscles in your neck. These
muscles allow you to rotate, flex, and extend your neck and shoulders.
▪ XII. Hypoglossal nerve
▪ Your hypoglossal nerve is the 12th cranial nerve which is responsible for the
movement of most of the muscles in your tongue.
The Autonomic Nervous System (ANS)
Autonomic means
It is concerned with regulation of
Cardiac Muscles
The ANS consist of two anatomically seperate systems
 Few exception organs of the body are innervated by both of these subdivisions.
 Each organ has a different effect.
Sympathetic Division
• Speeds the heart rate
• Slows it down.
Sympathetic Nervous System
▪ The sympathetic nervous system (SNS) is one of the
two divisions of the autonomic nervous system.
▪ Sympathetic nervous system is responsible for
“flight and fight response” and works contrary to
parasympathetic nervous system.
Anatomy of sympathetic Nervous System
▪ The sympathetic nervous system is composed of
many pathways that perform a variety of functions
on various organ systems.
▪ These nerves originate from lumbar and thoracic
region of spinal cord. The cell bodies of sympathetic
motor neurons are located in the gray matter of the
thoracic and lumbar regions of the spinal cord.
Functions of sympathetic Nervous system
▪ The SNS is best known for mediating the neuronal and
hormonal stress response commonly known as the fight-orflight response, also known as sympatho-adrenal
(sympathetic and adrenal glands physiological connection)
response of the body.
▪ The fight-or-flight response was first described by Walter
Bradford Cannon.
▪ His theory states that animals react to threats with a general
discharge of the sympathetic nervous system, priming the
animal for fighting or fleeing.
▪ The sympathetic division is most involved in activities associated with
expenditure of energy from reserves that are stored in the body.
▪ For example, when an organism is excited or feel threat the
sympathetic nervous system increases blood flow to skeletal muscles,
stimulates the secretion of epinephrine.
▪ The sympathetic nervous system is considered to be as most efficient
quickly responding system that prepares body for immediate action.
▪ The sympathetic nervous system is controlled by two stress
releasing hormones adrenaline and nor adrenaline which execute
following functions:
▪ Diverts blood flow away
and skin via vasoconstriction.
▪ Blood flow to skeletal muscles and the lungs is enhanced.
▪ Dilates bronchioles of the lung through circulating epinephrine
which allows for greater oxygen exchange.
▪ Increases heart rate.
▪ Dilates pupils allowing more light to enter the eye and
enhances far vision.
▪ Constricts all the intestinal sphincters and the urinary
▪ Inhibits peristalsis.
▪ Stimulates orgasm.
Physical indications of flight and fight response
Pathological issues of sympathetic Nervous System
▪ Urinary problems, such as difficulty starting urination, incontinence
▪ Sexual difficulties
▪ Difficulty digesting food, such as feeling full after a few bites of food, loss of appetite,
diarrhea, constipation, abdominal bloating, nausea, vomiting, difficulty swallowing and
heartburn, all due to changes in digestive function.
▪ Inability to recognize low blood sugar (hypoglycemia).
▪ Sweating abnormalities, such as sweating too much or too little.
▪ Sluggish pupil reaction, making it difficult to adjust from light to dark and seeing well when
driving at night.
▪ Dizziness.
Parasympathetic Nervous System
sends signals to and from different body parts via nerves.
Rest and digest.
Actions include digesting food, excreting waste, crying, salivating, or
becoming sexually aroused.
fight or flight.
Location in the Brain
Parasympathetic nerves begin in the medulla of the brain and at the middle area of the
spinal column, which contains the spinal cord. One of the nerves in the medulla is the
vague nerve, which is a part of the body that helps control the heart, lungs, and digestion
organs. The brain and spinal cord are important structures in the nervous system;
together, they make up the central nervous system (CNS). The nerves of the PSNS that
originate in the brain are called cranial nerves. Ganglia, or groups of nerve cell bodies,
are extensions of the nerves of the PSNS, and are found near or in the organs of the body
in order for signals to be sent to their target areas.
Functions of the Parasympathetic Nervous System
• It regulates bodily actions that happen without conscious thought.
• The PSNS works in conjunction with the SNS in order to maintain homeostasis in the body. For
example, during a fight or flight response, the SNS increases heart rate and blood pressure.
Afterward, the PSNS works to slow the heart rate down and lower blood pressure.
• It also starts up bodily processes that were temporarily put on hold when the SNS was activated,
such as digestion. During periods of rest, the body can devote energy to processes that are not
directly involved with fighting or fleeing.
▪ The PSNS and SNS regulate many parts of the body glands such as the salivary
glands and adrenal glands (which produce epinephrine, also called adrenaline, during
fight or flight).
▪ During a period of fight or flight, the pupils dilate to allow us to see more clearly and
make faster decisions. During rest and digest, the PSNS causes the pupils to
▪ The PSNS also causes increased digestion of food to occur, increased saliva and
mucous production, and increased secretion of urine from the kidneys.
Activating the Parasympathetic Nervous System to
Decrease Anxiety
Spend time in nature.
Get a massage.
Practice meditation.
Deep abdominal breathing from the diaphragm.
Repetitive prayer.
Play with animals or children.
Do something you enjoy, such as a favorite hobby.
End Of Topic