SlideShare a Scribd company logo
1 of 85
Download to read offline
Biswash Sapkota (M.Pharm) (B.Pharm)
Lecturer, Madan Bhandari Academy of
Health Sciences
Central Nervous system
CNS PART
 It consist of brain and spinal cord
 They are completely covered by layers called
meninges:
 The meninges has 3 layers:
1. Dura mater (outer): falx cerebri and tentorium
cerebelli
2. Arachnoids mater (middle): CSF
3. Pia mater (inner ) : connective tissues
containing blood vessels
• In between the Dura and arachnoid layer there is
a space called sub-dural space.
• The space between arachnoid and pia mater is
known as subarachnoid space and this contains
The brain and its parts
 The human brain
enables a person,
function intellectually,
express personality
and mood and interact
with environment .
 Is the part of CNS that
lies inside cranial
cavity .
 Has a average weight
1.5kg
 Received 15-20% of
total cardiac output.
 The brain is divided into different parts:
1. Forebrain(Telencephlon): it consist of cerebrum,
limbic system and some ganglia formed by
largest portion of brain.
2. Midbrain (Mesencephalon) : it includes corpora
quadrigemina and cerebral peduncles
3. Hindbrain ( Metencephalon): it includes pons,
cerebellum and medulla oblongata
The cerebrum
 This is the largest part of brain
 It is divided by a deep cleft, the longitudinal cerebral
fissure into right and left cerebral hemisphere each
containing one of the lateral ventricles
 Deep within the brain the hemisphere are connected
by a mass of white matter called corpus callosum.
 The falx cerebri is formed by dura mater.
 The surficial part of cerebrum is composed of nerve
cell called grey matter and the deeper layers is called
white matter.
 The cerebrum has many infoldings or furrows of
varying depth .
 The exposed area of folds are the gyri or
convolutions and they are separated by sulci or
fissures.
 These convolutions greatly increase surface area
of cerebrum
 For descriptive purpose each hemisphere of
cerebrum is divided into lobes which take the
names of the bones of cranium under which they
lie:
o Frontal lobe
o Parietal lobe
o Temporal lobe
 Within the brain there are 4 irregular shaped
cavities called ventricles which are called
ventricles which are filled with CSF
 Two lateral ventricles: Septum lucidum separate
each lateral ventricles . Connected to third
ventricle by interventricular foramen.
 3rd ventricles : communicate with 4th ventricle by
cerebral aqueduct
 4th ventricles : Diamond shaped , below 3rd
ventricle and between cerebellum and pons .
Communicate with subarachnoid space by
foramina in its roof.
Functions of cerebrum
 Mental activity involved in memory, intelligence,
sense of responsibility, thinking, reasoning, moral
sense and learning are attributed to higher
centers.
 Sensory perception, including the perception of
pain, temperature, touch, sight, hearing, taste and
smell
 Initiation and control of skeletal muscle
contraction
Basal nuclei :
 These are the areas of grey matter, lying deep
within the cerebral hemisphere, with connections
to cerebral cortex and thalamus
 The basal nuclei form the part of extrapyramidal
tracts and are thought to be involved in initiating
muscle tone in slow and coordinated activities .
 If control is inadequate or absent, movements are
jerky and uncoordinated .
Thalamus :
 The thalamus consists of two masses of nerve
cells and fibres situated within the cerebral
hemisphere just below the corpus callosum, one
on each side of third ventricle.
 Sensory input from skin, viscera and special
sense organ is transmitted to thalamus where
there is basic recognition .
 It is thought to be involved in the processing of
some emotions and complex reflexes.
 The thalamus relays and redistributes impulses
from parts of brain to cerebral cortex.
Hypothalamus :
 It is composed of number of groups of nerve cells
 It is situated Infront of thalamus just above pituitary
gland
 It is linked to posterior lobe of pituitary gland by nerve
fiber and to anterior lobe by a complex system of
blood vessels.
 Through these connections hypothalamus control the
output of hormones from gland
 It balance thirst and water balance
 Regulates body temperature
 Sexual behaviors, emotional reactions
 Biological clocks and circadian rhythms .
Midbrain (mesencephalon)
 It lies in between cerebrum and pons
 It connects forebrain to hindbrain
 It consist of nuclei and nerve fibres which
connect the cerebrum with lower parts of brain
and with spinal cord.
 The pineal body ( pineal organ, or pineal body,
endocrine gland found in vertebrates that is the
source of melatonin, a hormone derived from
tryptophan that plays a central role in the
regulation of circadian rhythm) lies in the midbrain
Pons
 The pons is situated Infront of cerebellum below
the midbrain and above the medulla oblongata.
 It contains the nerve fibres that form the bridge
between two hemisphere of cerebellum and fibre
passing to the higher levels of brain and spinal
cord.
 It contains the nuclei in pons that act as relay
stations and some are associated with cranial
nerves.
Medulla oblongata
 It extends from pons above to spinal cord below
 It lies within the cranial cavity
 It is 2.5cm long and lies and lies just above
foramen magnum.
 It contains the vital centers:
 cardiac centre control the rate and force of
cardiac contraction
 Respiratory centres control rate and depth of
respiration
 Vasomotor centre control blood pressure
 Reflex centers of vomiting, coughning, sneezing
and swallowing
Cerebellum
 Situated posterior to the pons and medulla and
just below cerebrum .
 Has two hemispheres, separated by a narrow
medial strip called vermis.
 It has important role in controlling muscle tone
and coordination of muscle movement so it is
concerned with maintenance of equilibrium and
balance of body.
 It controls same side of body.
 Damage to the cerebellum results in clumsy
uncoordinated muscular movement and inability
to carry out smooth, steady and precise
movement .
Spinal cord
 It is the elongated, cylindrical part of CNS
 It is suspended in vertebral canal, covered by
meninges
 Extended from C1 to lower boarder of L1
vertebrae.
 It is 45cm long, 1.25cm wide and wt 30g
 It acts as the communication between the brain
and rest of the body parts through the various
nerve tracts .
 It has outer white mater and inner grey mater
 Central canal is present inside the cord
 The cord gives origin for spinal nerves
Functions of spinal cord
 Reflex function
 The brain communication functions
Reflex Action
 When you touch a hot object or when a pin pricks
your finger, what is your immediate reaction? Of
course, you remove your hand away from the
source of pain, either the hot object or the pin. In
situations like these, your reactions are always
immediate, involuntary and sudden. They happen
without much of a thinking process. In scientific
terms, this action is called the reflex action.
 The whole mechanism of reflex action occurs in
such a fashion that there is no conscious control
of the brain. Stimulation occurs through the
peripheral nervous system and the response to
this peripheral nerve stimulation is involuntary. In
a reflex action, the spinal cord along with the
brain stem is responsible for the reflex
movements.
A few examples of reflex action are:
 When light acts as a stimulus, the pupil of the eye
changes in size.
 Sudden jerky withdrawal of hand or leg when
pricked by a pin.
 Coughing or sneezing, because of irritants in the
nasal passages.
 Knees jerk in response to a blow or someone
stamping the leg.
 The sudden removal of the hand from a sharp
object.
 Sudden blinking when an insect comes very near
to the eyes.
 The whole process of reflex action involves some
important components. They are receptor organs,
sensory neurons, nerve center, associated neurons,
motor neurons and effector neurons.
 The receptor organs perceive the stimuli. They are
situated on the sense organs. The afferent neurons or
the sensory neurons carry the stimuli from receptors
to the spinal cord. The ganglion of the spinal cord has
the sensory neurons.
 The spinal cord is the nerve center, where synaptic
connections are formed. The associated neurons are
present in the spinal cord. The ventral horn of spinal
cord has the motor neurons. Effector organs are the
glands and muscles that behave in response to the
stimuli.
Reflex Arc
 The neural pathway that controls the reflexes occurs
through the reflex arc. It acts on an impulse even
before it reaches the brain. There are some stimuli
that require an automatic, instantaneous response
without the need of conscious thought. The following
diagram shows the reflex arc pathway.
 The receptor here is the sense organ that senses
danger. The sensory neurons pick up signals from the
sensory organ and send them through other neurons
which are interconnected. It is then received by the
relay neuron which is present in the spinal cord.
Immediately, the spinal cord sends back signals to the
muscle through the motor neuron. The muscles
attached to the sense organ move the organ away
from danger. In reflex actions, the signals do not
travel up to the brain.
Neuro Humoral Transmission in CNS
 Neurohumoral transmission implies that nerves
transmit their message across synapses and
neuroeffector junctions by the release of humoral
(chemical) messengers.
Steps
 1. Impulse conduction The resting
transmembrane potential (70 mV negative inside)
is established by high K+ permeability of axonal
membrane and high axoplasmic concentration of
this ion coupled with low Na+ permeability and its
active extrusion from the neurone. Stimulation or
arrival of an electrical impulse causes a sudden
increase in Na+ conductance → depolarization
and overshoot (reverse polarization: inside
becoming 20 mV positive); K+ ions then move out
in the direction of their concentration gradient and
repolarization occurs. Ionic distribution is
normalized during the refractory period by the
activation of Na+ K+ pump. The action potential
(AP) thus generated sets up local circuit currents
which activate ionic channels at the next excitable
II. Transmitter release The transmitter (excitatory or
inhibitory) is stored in prejunctional nerve endings within
‘synaptic vesicles’ . Nerve impulse promotes fusion of
vesicular and axonal membranes through Ca2+ entry
which fluidizes membranes. All contents of the vesicle
(transmitter, enzymes and other proteins) are extruded
(exocytosis) in the junctional cleft.
The release process can be modulated by the
transmitter itself and by other agents through activation
of specific receptors located on the prejunctional
membrane, e.g. noradrenaline (NA) release is inhibited
by NA (α2 receptor), dopamine, adenosine,
prostaglandins and enkephalins while isoprenaline (β2
receptor) and angiotensin (AT1 receptor) increase NA
release. Similarly, α2 and muscarinic agonists inhibit
acetylcholine (ACh) release at autonomic neuroeffector
sites (but not in ganglia and skeletal muscles).
III. Transmitter action on postjunctional
membrane The released transmitter combines with
specific receptors on the postjunctional membrane
and depending on its nature induces an excitatory
postsynaptic potential (EPSP) or an inhibitory
postsynaptic potential (IPSP).
IV. Postjunctional activity A suprathreshold EPSP
generates a propagated postjunctional AP which results
in nerve impulse (in neurone), contraction (in muscle) or
secretion (in gland). An IPSP stabilizes the
postjunctional membrane and resists depolarizing
stimuli.
V. Termination of transmitter action Following its
combination with the receptor, the transmitter is either
locally degraded (e.g. ACh) or is taken back into the
prejunctional neurone by active uptake or diffuses away
(e.g. NA, GABA). Specific carrier proteins like
norepinephrine transporter (NET), dopamine transporter
(DAT), serotonin transporter (SERT) are expressed on
the axonal membrane for this purpose. The rate of
termination of transmitter action governs the rate at
which responses can be transmitted across a junction
(1 to 1000/sec).
Write about GREY and WHITE
MATER????
Cranial Nerves and their
functions
 The peripheral nervous system is made up of all
the nerves and nerves centers of the outlying or
peripheral part of body
 Any part of the nervous system not contained in
the CNS is a component of peripheral nervous
system. Or when they exist out from the CNS .
The main subdivision are cranial and spinal
nerve.
 The PNS consist of
 12 pairs of cranial nerve
 31 pairs of spinal nerves
 There are 12 pairs of cranial nerves originating
from the brain
 1st and 2nd cranial nerves arise from cerebrum
 3rd and 4th arise from midbrain
 5th and 6th arise from pons and
 9th -12th arise from medulla
 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 nerves : The olfactory nerve transmits
sensory information to your brain regarding smells
that you encounter.
When you inhale aromatic molecules, they dissolve
in a moist lining at the roof of your nasal cavity,
called the olfactory epithelium. This stimulates
receptors that generate nerve impulses that move
to your olfactory bulb. Your olfactory bulb is an oval-
shaped structure that contains specialized groups
of nerve cells.
From the olfactory bulb, nerves pass into your
olfactory tract, which is located below the frontal
lobe of your brain. Nerve signals are then sent to
areas of your brain concerned with memory and
recognition of smells.
II. Optic nerve : The optic nerve is the sensory nerve
that involves vision.
When light enters your eye, it comes into contact with
special receptors in your retina called rods and cones.
Rods are found in large numbers and are highly
sensitive to light. They’re more specialized for black and
white or night vision.
Cones are present in smaller numbers. They have a
lower light sensitivity than rods and are more involved
with color vision.
The information received by your rods and cones is
transmitted from your retina to your optic nerve. Once
inside your skull, both of your optic nerves meet to form
something called the optic chiasm. At the optic chiasm,
nerve fibers from half of each retina form two separate
optic tracts.
Through each optic tract, the nerve impulses eventually
reach your visual cortex, which then processes the
information. Your visual cortex is located in the back
part of your brain.
III. Oculomotor nerve
The oculomotor nerve has two different motor
functions: muscle function and pupil response.
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.
This nerve originates in the front part of your
midbrain, which is a part of your brainstem. It moves
forward from that area until it reaches the area of
your eye sockets.
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.
It emerges from the back part of your midbrain. Like
your oculomotor nerve, it moves forward until it
reaches your eye sockets, where it stimulates the
superior oblique muscle.
Iv . Trigeminal nerve : The trigeminal nerve is the largest of
your cranial nerves and has both sensory and motor functions.
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.
The trigeminal nerve originates from a group of nuclei —
which is a collection of nerve cells — in the midbrain and
medulla regions of your brainstem. Eventually, these nuclei
form a separate sensory root and motor root.
The sensory root of your trigeminal nerve branches into the
ophthalmic, maxillary, and mandibular divisions. The motor
root of your trigeminal nerve passes below the sensory root
and is only distributed into the mandibular division.
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.
This nerve, also called the abducent nerve, starts in
the pons region of your brainstem. It eventually
enters your eye socket, where it controls the lateral
rectus muscle.
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 glands
 communicating sensations from the outer parts of
your ear
 Your facial nerve has a very complex path. It
originates in the pons area of your brainstem, where it
has both a motor and sensory root. Eventually, the
two nerves fuse together to form the facial nerve.
 Both within and outside of your skull, the facial nerve
branches further into smaller nerve fibers that
stimulate muscles and glands or provide sensory
information.
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.
 The cochlear and vestibular portions of your
vestibulocochlear nerve originate in separate areas of the
brain.
 The cochlear portion starts in an area of your brain called
the inferior cerebellar peduncle. The vestibular portion
begins in your pons and medulla. Both portions combine to
form the vestibulocochlear nerve.
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 stylopharyngeus
The glossopharyngeal nerve originates in a part of
your brainstem called the medulla oblongata. It
eventually extends into your neck and throat region.
X. Vagus nerve:
The vagus nerve is a very diverse nerve. It has both
sensory and motor functions, including:
 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
Out of all of the cranial nerves, the vagus nerve has the
longest pathway. It extends from your head all the way
into your abdomen. It originates in the part of your
brainstem called the medulla.
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.
 It’s divided into two parts: spinal and cranial. The
spinal portion originates in the upper part of your
spinal cord. The cranial part starts in your medulla
oblongata.
 These parts meet briefly before the spinal part of
the nerve moves to supply the muscles of your
neck while the cranial part follows the vagus
nerve
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. It
starts in the medulla oblongata and moves down
into the jaw, where it reaches the tongue
Specialized function of Brain
The main areas of cerebrum associated with
sensory perception and voluntary motor activity are
know but it is unlikely that any area is associated
exclusively with only one function. Except where
specially mentioned, the different areas are active
in both hemispheres.
Motor areas of cerebrum
a. The precentral (motor) areas:
• This lies in frontal lobe immediately anterior to the
central sulcus
• The cell bodies are pyramid cells (Betzs Cell) and
initiate the contraction of skeletal muscles.
• A nerve fiber from a Betzs cells passes downwards to
medulla oblongata and descend to the spinal cord.
• At special point in spinal cord the nerve impulse
crosses a synapse to stimulate second neurone which
terminate at the motor end-plate of muscle fibre.
• The motor area at the right hemisphere of cerebrum
controls voluntary muscle movement on left side of
body and vice versa.
 The neurone with this cell body in
cerebrum is the upper motor
neurone and the other cell body in
the spinal cord is called lower
motor neurone. Damage to either
of these neurons may result in
paralysis.
 The motor area control various
part like head, neck, face and
fingers, feet .
b. The premotor area :
 This lies in the frontal lobes immediately anterior
to the motor area .
 The cells are thought to control the motor area
ensuring and orderly series of movements.
 For example while writing many muscles
contracts but the movement must be coordinated
and carried out in particular sequence. Such
patterns of movement when established is
described as manual dexternity .
 In the lower part just above the lateral sulcus
there is a motor speech area which control the
movement necessary for speech. This is
dominate in left hemisphere.
c. The frontal area:
 This extends anteriorly from the premotor area to
include the remainder of frontal lobe .
 it is large area and is more highly developed in
humans than in other animals.
 This is thought that the communication between
this and other part of cerebrum are responsible
for behavior, character and emotional state of
individual.
Sensory areas of cerebrum
a. Post central (sensory ) area :
• This is the area behind the central sulcus.
• The sensation of pain, temperature, pressure and
touch, knowledge of muscular movement and
position of joint are received.
• The sensory area of right hemisphere receives
the impulses from left side of the body and vice
versa .
• The large area of face is consistent with the
extensive sensory nerve supply by the three
branches of trigeminal nerves.
b. The parietal area:
 This lies behind the post central area and
includes the greater part of parietal lobe of
cerebrum .
 The function of this part is to gain and acquire the
particular knowledge of the objects.
 This is thought that the object can be recognized
by the touch alone because of the knowledge
from the past experience retained in this area.
c. The sensory speech area :
 This is situated in the lower part of parietal lobe
and extends upto temporal lobe.
 It is here the spoken words is perceived
 It is dominated in the left hemisphere in the right
handed people and vice versa.
d. The auditory area :
 This lies immediately below lateral sulcus within
the temporal lobe .
 The cell receive and interpret impulses
transmitted from the inner ear by cochlear
(auditory) part of vestibulocochlear nerves (8th
cranial nerve ) .
e. The olfactory (smell) area :
 This lies deep within the temporal lobe where
impulses from nose via the olfactory nerve (1st
cranial nerves) are received and perceived.
f. The taste area :
 This is thought to lie just above the lateral sulcus
in the deep layers of sensory area.
 This is the area where impulses from special
nerve ending in the taste buds in tongue and in
the lining of cheeks, palatae and pharynx are
perceived as taste.
g. The visual area :
 This lies behind the parietal and occipital sulcus
and include greater part of occipital lobe.
 The optic nerves pass from the eye to this area
which receives and interprets the impulses as
visual impressions.
Other areas of cerebrum are also
1. Basal nuclei
2. Thalamus
3. Hypothalamus
PYRAMIDAL TRACTS
INCLUDES:
1.Corticospinal tract
2.Corticobulbar tract
* These are aggregations of upper motor neuron.
*nerve fibres travel from Cerebral cortex and
terminate either in brain stem(corticobulbar) or
spinal cord(corticospinal).
*Transmit moter impulses that control motor
functions of body.
Pyramidal Tract
CORTICOBULBAR TRACT
• Conduct impulses from the brain to the cranial
nerves.
• Fibres from the ventral motor cortex travel with
corticospinal tract through the internal capsule.
• The UMNs synapse directly with the LMNs
located in the motor cranial nerve nuclei:-
NAMELY- Oculomotor,
TROCHLEAR, TRIGEMINAL, ABDUCENS, FACIAL and
ACCESSORY and in the nucleus ambiguus to the
HYPOGLOSSAL, VAGUS AND ACCESSORY NERVES
CORTICOSPINAL TRACT
• It originate from PYRAMIDAL CELLS in layer V
of the cerebral cotex.
• PRIMARY MOTOR CORTEX
• SUPPLEMENTARY MOTOR AREA
• PREMOTOR CORTEX
• SOMATOSENSORY CORTEX
• PARIETAL LOBE
• CINGULATE GYRUS
• The cells have their bodies in cerebral cotex
and AXONS form the bulk of the pyramidal
tracts.
• The nerve axons travel from the cortex
through the cerebral peduncle and into the
brainstem and anterior medulla.
• Here they form two prominences called
PYRAMIDS OF THE MEDULLA.
• The axons that cross over move to outer part
of the medulla and form the LATERAL
CORTICOSPINAL TRACT.
• Whereas the fibres that remain form the
ANTERIOR CORTICOSPINAL TRACT.
• About 80% of axons cross over and form LCS
TRACT. 20% do not cross AND form ACS
TRACT.
• Termination in spinal cord: mostly laminae
3-7, few in ventral horn and laminae 1-2;
mostly innervating interneurons, although
some innervation of alpha motor neurons
• Neurotransmitter: glutamate and/or
aspartate
FUNCTIONS
CORTICOBULBAR TRACT-
-SWALLOWING
-PHONATION
-MOVEMENTS OF THE TONGUE
-FACIAL EXPRESSION
CORTIOSPINAL TRACT-
-INVOLVED MOVEMENT OF MUSCLES OF BODY.
CLINICAL SEGNIFICANCE
• Damage to the Corticospinal Tracts
• The pyramidal tracts are susceptible to damage, because they extend
almost the whole length of the central nervous system. As mentioned
previously, they particularly vulnerable as they pass through the internal
capsule – a common site of cerebrovascular accidents (CVA).
• If there is only a unilateral lesion of the left or right corticospinal tract,
symptoms will appear on the contralateral side of the body. The cardinal
signs of an upper motor neurone lesion are:
• Hypertonia – an increased muscle tone
• Hyperreflexia – increased muscle reflexes
• Clonus – involuntary, rhythmic muscle contractions
• Babinski sign – extension of the hallux in response to blunt stimulation of
the sole of the foot
• Muscle weakness
• Damage to the Corticobulbar Tracts
• Due to the bilateral nature of the majority of the
corticobulbar tracts, a unilateral lesion usually results in
mild muscle weakness. However, not all the cranial nerves
receive bilateral input, and so there are a few exceptions:
• Hypoglossal nerve – a lesion to the upper motor neurones
for CN XII will result in spastic paralysis of the contralateral
side of the genioglossus. This will result in the deviation of
the tongue to the contralateral side.
• Facial nerve – a lesion to the upper motor neurones for CN
VII will result in spastic paralysis of the muscles in the
contralateral lower quadrant of the face.
CSF ??????
Thank YOU

More Related Content

What's hot

Central Nervous System, The Autonomic Nervous System
Central Nervous System, The Autonomic Nervous SystemCentral Nervous System, The Autonomic Nervous System
Central Nervous System, The Autonomic Nervous Systemcarmencrivii
 
Vegetative (autonomic) system
Vegetative (autonomic) systemVegetative (autonomic) system
Vegetative (autonomic) systemAmanda Hess
 
Introduction to nervous system, Divisions of Nervous System, Nervous System P...
Introduction to nervous system, Divisions of Nervous System, Nervous System P...Introduction to nervous system, Divisions of Nervous System, Nervous System P...
Introduction to nervous system, Divisions of Nervous System, Nervous System P...Shaista Jabeen
 
Nervous System
Nervous SystemNervous System
Nervous Systemitutor
 
Peripheral nerve system
Peripheral nerve systemPeripheral nerve system
Peripheral nerve systemAmen Ullah
 
Anatomy of autonomic nervous system
Anatomy of autonomic nervous systemAnatomy of autonomic nervous system
Anatomy of autonomic nervous systemMBBS IMS MSU
 
Classification of Nervous System
Classification of Nervous SystemClassification of Nervous System
Classification of Nervous SystemSalmaAsghar4
 
NERVOUS SYSTEM and it's division
NERVOUS SYSTEM and it's divisionNERVOUS SYSTEM and it's division
NERVOUS SYSTEM and it's divisionSyeda Maryam
 
Autonomic nervous system
Autonomic nervous systemAutonomic nervous system
Autonomic nervous systemEman Abdallah
 

What's hot (20)

Nervous system
Nervous systemNervous system
Nervous system
 
Central Nervous System, The Autonomic Nervous System
Central Nervous System, The Autonomic Nervous SystemCentral Nervous System, The Autonomic Nervous System
Central Nervous System, The Autonomic Nervous System
 
Nervous system
Nervous systemNervous system
Nervous system
 
Vegetative (autonomic) system
Vegetative (autonomic) systemVegetative (autonomic) system
Vegetative (autonomic) system
 
Nervous system
Nervous systemNervous system
Nervous system
 
Introduction to nervous system, Divisions of Nervous System, Nervous System P...
Introduction to nervous system, Divisions of Nervous System, Nervous System P...Introduction to nervous system, Divisions of Nervous System, Nervous System P...
Introduction to nervous system, Divisions of Nervous System, Nervous System P...
 
CNS (Central Nervous System)
CNS (Central Nervous System)CNS (Central Nervous System)
CNS (Central Nervous System)
 
Unit 1 nervous system
Unit 1 nervous systemUnit 1 nervous system
Unit 1 nervous system
 
Nervous System
Nervous SystemNervous System
Nervous System
 
1. Physiology
1. Physiology1. Physiology
1. Physiology
 
Peripheral nerve system
Peripheral nerve systemPeripheral nerve system
Peripheral nerve system
 
Anatomy of autonomic nervous system
Anatomy of autonomic nervous systemAnatomy of autonomic nervous system
Anatomy of autonomic nervous system
 
Classification of Nervous System
Classification of Nervous SystemClassification of Nervous System
Classification of Nervous System
 
Pns
PnsPns
Pns
 
Nervous system
Nervous systemNervous system
Nervous system
 
NERVOUS SYSTEM and it's division
NERVOUS SYSTEM and it's divisionNERVOUS SYSTEM and it's division
NERVOUS SYSTEM and it's division
 
Autonomic nervous system
Autonomic nervous systemAutonomic nervous system
Autonomic nervous system
 
Nervous system
Nervous systemNervous system
Nervous system
 
Nerve
NerveNerve
Nerve
 
Pns 7-
Pns 7-Pns 7-
Pns 7-
 

Similar to Unit 2 central nervous system

Similar to Unit 2 central nervous system (20)

Ingles expo
Ingles expoIngles expo
Ingles expo
 
Coordination 1
Coordination  1Coordination  1
Coordination 1
 
Nervous system
Nervous systemNervous system
Nervous system
 
CNS AND PNS NURSING .pptx1-1.pptx
CNS AND PNS NURSING .pptx1-1.pptxCNS AND PNS NURSING .pptx1-1.pptx
CNS AND PNS NURSING .pptx1-1.pptx
 
Neurological Basis Of Behavior Presentation.pptx
Neurological Basis Of Behavior Presentation.pptxNeurological Basis Of Behavior Presentation.pptx
Neurological Basis Of Behavior Presentation.pptx
 
control and coordination class 10 NCERT pdf notes
control and coordination class 10 NCERT pdf notescontrol and coordination class 10 NCERT pdf notes
control and coordination class 10 NCERT pdf notes
 
HUMAN BRAIN.pptx
HUMAN BRAIN.pptxHUMAN BRAIN.pptx
HUMAN BRAIN.pptx
 
Lecture 7 physiology of the nervous system
Lecture 7 physiology of the nervous systemLecture 7 physiology of the nervous system
Lecture 7 physiology of the nervous system
 
Psychology
PsychologyPsychology
Psychology
 
Neural control
Neural  control Neural  control
Neural control
 
Nervous system
Nervous systemNervous system
Nervous system
 
The nervous system
The nervous systemThe nervous system
The nervous system
 
CNS
CNSCNS
CNS
 
Anatomy of ns
Anatomy of nsAnatomy of ns
Anatomy of ns
 
Control and coordination
Control and coordinationControl and coordination
Control and coordination
 
Nervous system
Nervous systemNervous system
Nervous system
 
Nervous system ppt.pptx
Nervous system ppt.pptxNervous system ppt.pptx
Nervous system ppt.pptx
 
Ch50
Ch50Ch50
Ch50
 
Nervous system and coordination brian & friends para 4to
Nervous system and coordination brian & friends para 4toNervous system and coordination brian & friends para 4to
Nervous system and coordination brian & friends para 4to
 
Nervoussystem
NervoussystemNervoussystem
Nervoussystem
 

More from Biswash Sapkota

Cpcsea guidelines for laboratory animal facility
Cpcsea guidelines for laboratory animal facilityCpcsea guidelines for laboratory animal facility
Cpcsea guidelines for laboratory animal facilityBiswash Sapkota
 
Unt 1 respiratory system
Unt 1 respiratory systemUnt 1 respiratory system
Unt 1 respiratory systemBiswash Sapkota
 
Current trends in pharmacy profession
Current trends in pharmacy professionCurrent trends in pharmacy profession
Current trends in pharmacy professionBiswash Sapkota
 
Pharmacological screening of analgesic activity
Pharmacological screening of analgesic activityPharmacological screening of analgesic activity
Pharmacological screening of analgesic activityBiswash Sapkota
 
Wilcoxon signed rank test
Wilcoxon signed rank testWilcoxon signed rank test
Wilcoxon signed rank testBiswash Sapkota
 

More from Biswash Sapkota (11)

Financial literacy
Financial literacyFinancial literacy
Financial literacy
 
Share market basic
Share market basicShare market basic
Share market basic
 
Cpcsea guidelines for laboratory animal facility
Cpcsea guidelines for laboratory animal facilityCpcsea guidelines for laboratory animal facility
Cpcsea guidelines for laboratory animal facility
 
Silver nano particles
Silver nano particlesSilver nano particles
Silver nano particles
 
Unit 4 urinary system
Unit 4 urinary systemUnit 4 urinary system
Unit 4 urinary system
 
Unt 1 respiratory system
Unt 1 respiratory systemUnt 1 respiratory system
Unt 1 respiratory system
 
Current trends in pharmacy profession
Current trends in pharmacy professionCurrent trends in pharmacy profession
Current trends in pharmacy profession
 
Pharmacological screening of analgesic activity
Pharmacological screening of analgesic activityPharmacological screening of analgesic activity
Pharmacological screening of analgesic activity
 
X ray crystallography
X ray crystallographyX ray crystallography
X ray crystallography
 
Wilcoxon signed rank test
Wilcoxon signed rank testWilcoxon signed rank test
Wilcoxon signed rank test
 
Swine flu
Swine fluSwine flu
Swine flu
 

Recently uploaded

Music Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara Rajendran
Music Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara RajendranMusic Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara Rajendran
Music Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara RajendranTara Rajendran
 
Apiculture Chapter 1. Introduction 2.ppt
Apiculture Chapter 1. Introduction 2.pptApiculture Chapter 1. Introduction 2.ppt
Apiculture Chapter 1. Introduction 2.pptkedirjemalharun
 
History and Development of Pharmacovigilence.pdf
History and Development of Pharmacovigilence.pdfHistory and Development of Pharmacovigilence.pdf
History and Development of Pharmacovigilence.pdfSasikiranMarri
 
PERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptx
PERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptxPERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptx
PERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptxdrashraf369
 
Nutrition of OCD for my Nutritional Neuroscience Class
Nutrition of OCD for my Nutritional Neuroscience ClassNutrition of OCD for my Nutritional Neuroscience Class
Nutrition of OCD for my Nutritional Neuroscience Classmanuelazg2001
 
Primary headache and facial pain. (2024)
Primary headache and facial pain. (2024)Primary headache and facial pain. (2024)
Primary headache and facial pain. (2024)Mohamed Rizk Khodair
 
MedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdf
MedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdfMedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdf
MedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdfSasikiranMarri
 
Tans femoral Amputee : Prosthetics Knee Joints.pptx
Tans femoral Amputee : Prosthetics Knee Joints.pptxTans femoral Amputee : Prosthetics Knee Joints.pptx
Tans femoral Amputee : Prosthetics Knee Joints.pptxKezaiah S
 
Measurement of Radiation and Dosimetric Procedure.pptx
Measurement of Radiation and Dosimetric Procedure.pptxMeasurement of Radiation and Dosimetric Procedure.pptx
Measurement of Radiation and Dosimetric Procedure.pptxDr. Dheeraj Kumar
 
epilepsy and status epilepticus for undergraduate.pptx
epilepsy and status epilepticus  for undergraduate.pptxepilepsy and status epilepticus  for undergraduate.pptx
epilepsy and status epilepticus for undergraduate.pptxMohamed Rizk Khodair
 
CEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand University
CEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand UniversityCEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand University
CEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand UniversityHarshChauhan475104
 
Wessex Health Partners Wessex Integrated Care, Population Health, Research & ...
Wessex Health Partners Wessex Integrated Care, Population Health, Research & ...Wessex Health Partners Wessex Integrated Care, Population Health, Research & ...
Wessex Health Partners Wessex Integrated Care, Population Health, Research & ...Wessex Health Partners
 
Glomerular Filtration and determinants of glomerular filtration .pptx
Glomerular Filtration and  determinants of glomerular filtration .pptxGlomerular Filtration and  determinants of glomerular filtration .pptx
Glomerular Filtration and determinants of glomerular filtration .pptxDr.Nusrat Tariq
 
97111 47426 Call Girls In Delhi MUNIRKAA
97111 47426 Call Girls In Delhi MUNIRKAA97111 47426 Call Girls In Delhi MUNIRKAA
97111 47426 Call Girls In Delhi MUNIRKAAjennyeacort
 
low cost antibiotic cement nail for infected non union.pptx
low cost antibiotic cement nail for infected non union.pptxlow cost antibiotic cement nail for infected non union.pptx
low cost antibiotic cement nail for infected non union.pptxdrashraf369
 
maternal mortality and its causes and how to reduce maternal mortality
maternal mortality and its causes and how to reduce maternal mortalitymaternal mortality and its causes and how to reduce maternal mortality
maternal mortality and its causes and how to reduce maternal mortalityhardikdabas3
 
Basic principles involved in the traditional systems of medicine PDF.pdf
Basic principles involved in the traditional systems of medicine PDF.pdfBasic principles involved in the traditional systems of medicine PDF.pdf
Basic principles involved in the traditional systems of medicine PDF.pdfDivya Kanojiya
 
Giftedness: Understanding Everyday Neurobiology for Self-Knowledge
Giftedness: Understanding Everyday Neurobiology for Self-KnowledgeGiftedness: Understanding Everyday Neurobiology for Self-Knowledge
Giftedness: Understanding Everyday Neurobiology for Self-Knowledgeassessoriafabianodea
 
ANTI-DIABETICS DRUGS - PTEROCARPUS AND GYMNEMA
ANTI-DIABETICS DRUGS - PTEROCARPUS AND GYMNEMAANTI-DIABETICS DRUGS - PTEROCARPUS AND GYMNEMA
ANTI-DIABETICS DRUGS - PTEROCARPUS AND GYMNEMADivya Kanojiya
 
Case Report Peripartum Cardiomyopathy.pptx
Case Report Peripartum Cardiomyopathy.pptxCase Report Peripartum Cardiomyopathy.pptx
Case Report Peripartum Cardiomyopathy.pptxNiranjan Chavan
 

Recently uploaded (20)

Music Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara Rajendran
Music Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara RajendranMusic Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara Rajendran
Music Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara Rajendran
 
Apiculture Chapter 1. Introduction 2.ppt
Apiculture Chapter 1. Introduction 2.pptApiculture Chapter 1. Introduction 2.ppt
Apiculture Chapter 1. Introduction 2.ppt
 
History and Development of Pharmacovigilence.pdf
History and Development of Pharmacovigilence.pdfHistory and Development of Pharmacovigilence.pdf
History and Development of Pharmacovigilence.pdf
 
PERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptx
PERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptxPERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptx
PERFECT BUT PAINFUL TKR -ROLE OF SYNOVECTOMY.pptx
 
Nutrition of OCD for my Nutritional Neuroscience Class
Nutrition of OCD for my Nutritional Neuroscience ClassNutrition of OCD for my Nutritional Neuroscience Class
Nutrition of OCD for my Nutritional Neuroscience Class
 
Primary headache and facial pain. (2024)
Primary headache and facial pain. (2024)Primary headache and facial pain. (2024)
Primary headache and facial pain. (2024)
 
MedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdf
MedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdfMedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdf
MedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdf
 
Tans femoral Amputee : Prosthetics Knee Joints.pptx
Tans femoral Amputee : Prosthetics Knee Joints.pptxTans femoral Amputee : Prosthetics Knee Joints.pptx
Tans femoral Amputee : Prosthetics Knee Joints.pptx
 
Measurement of Radiation and Dosimetric Procedure.pptx
Measurement of Radiation and Dosimetric Procedure.pptxMeasurement of Radiation and Dosimetric Procedure.pptx
Measurement of Radiation and Dosimetric Procedure.pptx
 
epilepsy and status epilepticus for undergraduate.pptx
epilepsy and status epilepticus  for undergraduate.pptxepilepsy and status epilepticus  for undergraduate.pptx
epilepsy and status epilepticus for undergraduate.pptx
 
CEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand University
CEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand UniversityCEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand University
CEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand University
 
Wessex Health Partners Wessex Integrated Care, Population Health, Research & ...
Wessex Health Partners Wessex Integrated Care, Population Health, Research & ...Wessex Health Partners Wessex Integrated Care, Population Health, Research & ...
Wessex Health Partners Wessex Integrated Care, Population Health, Research & ...
 
Glomerular Filtration and determinants of glomerular filtration .pptx
Glomerular Filtration and  determinants of glomerular filtration .pptxGlomerular Filtration and  determinants of glomerular filtration .pptx
Glomerular Filtration and determinants of glomerular filtration .pptx
 
97111 47426 Call Girls In Delhi MUNIRKAA
97111 47426 Call Girls In Delhi MUNIRKAA97111 47426 Call Girls In Delhi MUNIRKAA
97111 47426 Call Girls In Delhi MUNIRKAA
 
low cost antibiotic cement nail for infected non union.pptx
low cost antibiotic cement nail for infected non union.pptxlow cost antibiotic cement nail for infected non union.pptx
low cost antibiotic cement nail for infected non union.pptx
 
maternal mortality and its causes and how to reduce maternal mortality
maternal mortality and its causes and how to reduce maternal mortalitymaternal mortality and its causes and how to reduce maternal mortality
maternal mortality and its causes and how to reduce maternal mortality
 
Basic principles involved in the traditional systems of medicine PDF.pdf
Basic principles involved in the traditional systems of medicine PDF.pdfBasic principles involved in the traditional systems of medicine PDF.pdf
Basic principles involved in the traditional systems of medicine PDF.pdf
 
Giftedness: Understanding Everyday Neurobiology for Self-Knowledge
Giftedness: Understanding Everyday Neurobiology for Self-KnowledgeGiftedness: Understanding Everyday Neurobiology for Self-Knowledge
Giftedness: Understanding Everyday Neurobiology for Self-Knowledge
 
ANTI-DIABETICS DRUGS - PTEROCARPUS AND GYMNEMA
ANTI-DIABETICS DRUGS - PTEROCARPUS AND GYMNEMAANTI-DIABETICS DRUGS - PTEROCARPUS AND GYMNEMA
ANTI-DIABETICS DRUGS - PTEROCARPUS AND GYMNEMA
 
Case Report Peripartum Cardiomyopathy.pptx
Case Report Peripartum Cardiomyopathy.pptxCase Report Peripartum Cardiomyopathy.pptx
Case Report Peripartum Cardiomyopathy.pptx
 

Unit 2 central nervous system

  • 1. Biswash Sapkota (M.Pharm) (B.Pharm) Lecturer, Madan Bhandari Academy of Health Sciences Central Nervous system
  • 2.
  • 3. CNS PART  It consist of brain and spinal cord  They are completely covered by layers called meninges:  The meninges has 3 layers: 1. Dura mater (outer): falx cerebri and tentorium cerebelli 2. Arachnoids mater (middle): CSF 3. Pia mater (inner ) : connective tissues containing blood vessels • In between the Dura and arachnoid layer there is a space called sub-dural space. • The space between arachnoid and pia mater is known as subarachnoid space and this contains
  • 4.
  • 5. The brain and its parts  The human brain enables a person, function intellectually, express personality and mood and interact with environment .  Is the part of CNS that lies inside cranial cavity .  Has a average weight 1.5kg  Received 15-20% of total cardiac output.
  • 6.
  • 7.  The brain is divided into different parts: 1. Forebrain(Telencephlon): it consist of cerebrum, limbic system and some ganglia formed by largest portion of brain. 2. Midbrain (Mesencephalon) : it includes corpora quadrigemina and cerebral peduncles 3. Hindbrain ( Metencephalon): it includes pons, cerebellum and medulla oblongata
  • 8.
  • 10.  This is the largest part of brain  It is divided by a deep cleft, the longitudinal cerebral fissure into right and left cerebral hemisphere each containing one of the lateral ventricles  Deep within the brain the hemisphere are connected by a mass of white matter called corpus callosum.  The falx cerebri is formed by dura mater.  The surficial part of cerebrum is composed of nerve cell called grey matter and the deeper layers is called white matter.  The cerebrum has many infoldings or furrows of varying depth .
  • 11.  The exposed area of folds are the gyri or convolutions and they are separated by sulci or fissures.  These convolutions greatly increase surface area of cerebrum  For descriptive purpose each hemisphere of cerebrum is divided into lobes which take the names of the bones of cranium under which they lie: o Frontal lobe o Parietal lobe o Temporal lobe
  • 12.
  • 13.
  • 14.  Within the brain there are 4 irregular shaped cavities called ventricles which are called ventricles which are filled with CSF  Two lateral ventricles: Septum lucidum separate each lateral ventricles . Connected to third ventricle by interventricular foramen.  3rd ventricles : communicate with 4th ventricle by cerebral aqueduct  4th ventricles : Diamond shaped , below 3rd ventricle and between cerebellum and pons . Communicate with subarachnoid space by foramina in its roof.
  • 15.
  • 16.
  • 17. Functions of cerebrum  Mental activity involved in memory, intelligence, sense of responsibility, thinking, reasoning, moral sense and learning are attributed to higher centers.  Sensory perception, including the perception of pain, temperature, touch, sight, hearing, taste and smell  Initiation and control of skeletal muscle contraction
  • 18. Basal nuclei :  These are the areas of grey matter, lying deep within the cerebral hemisphere, with connections to cerebral cortex and thalamus  The basal nuclei form the part of extrapyramidal tracts and are thought to be involved in initiating muscle tone in slow and coordinated activities .  If control is inadequate or absent, movements are jerky and uncoordinated .
  • 19. Thalamus :  The thalamus consists of two masses of nerve cells and fibres situated within the cerebral hemisphere just below the corpus callosum, one on each side of third ventricle.  Sensory input from skin, viscera and special sense organ is transmitted to thalamus where there is basic recognition .  It is thought to be involved in the processing of some emotions and complex reflexes.  The thalamus relays and redistributes impulses from parts of brain to cerebral cortex.
  • 20. Hypothalamus :  It is composed of number of groups of nerve cells  It is situated Infront of thalamus just above pituitary gland  It is linked to posterior lobe of pituitary gland by nerve fiber and to anterior lobe by a complex system of blood vessels.  Through these connections hypothalamus control the output of hormones from gland  It balance thirst and water balance  Regulates body temperature  Sexual behaviors, emotional reactions  Biological clocks and circadian rhythms .
  • 21.
  • 22. Midbrain (mesencephalon)  It lies in between cerebrum and pons  It connects forebrain to hindbrain  It consist of nuclei and nerve fibres which connect the cerebrum with lower parts of brain and with spinal cord.  The pineal body ( pineal organ, or pineal body, endocrine gland found in vertebrates that is the source of melatonin, a hormone derived from tryptophan that plays a central role in the regulation of circadian rhythm) lies in the midbrain
  • 23. Pons  The pons is situated Infront of cerebellum below the midbrain and above the medulla oblongata.  It contains the nerve fibres that form the bridge between two hemisphere of cerebellum and fibre passing to the higher levels of brain and spinal cord.  It contains the nuclei in pons that act as relay stations and some are associated with cranial nerves.
  • 24. Medulla oblongata  It extends from pons above to spinal cord below  It lies within the cranial cavity  It is 2.5cm long and lies and lies just above foramen magnum.  It contains the vital centers:  cardiac centre control the rate and force of cardiac contraction  Respiratory centres control rate and depth of respiration  Vasomotor centre control blood pressure  Reflex centers of vomiting, coughning, sneezing and swallowing
  • 25.
  • 26. Cerebellum  Situated posterior to the pons and medulla and just below cerebrum .  Has two hemispheres, separated by a narrow medial strip called vermis.  It has important role in controlling muscle tone and coordination of muscle movement so it is concerned with maintenance of equilibrium and balance of body.  It controls same side of body.  Damage to the cerebellum results in clumsy uncoordinated muscular movement and inability to carry out smooth, steady and precise movement .
  • 27. Spinal cord  It is the elongated, cylindrical part of CNS  It is suspended in vertebral canal, covered by meninges  Extended from C1 to lower boarder of L1 vertebrae.  It is 45cm long, 1.25cm wide and wt 30g  It acts as the communication between the brain and rest of the body parts through the various nerve tracts .  It has outer white mater and inner grey mater  Central canal is present inside the cord  The cord gives origin for spinal nerves
  • 28.
  • 29.
  • 30. Functions of spinal cord  Reflex function  The brain communication functions
  • 31. Reflex Action  When you touch a hot object or when a pin pricks your finger, what is your immediate reaction? Of course, you remove your hand away from the source of pain, either the hot object or the pin. In situations like these, your reactions are always immediate, involuntary and sudden. They happen without much of a thinking process. In scientific terms, this action is called the reflex action.
  • 32.  The whole mechanism of reflex action occurs in such a fashion that there is no conscious control of the brain. Stimulation occurs through the peripheral nervous system and the response to this peripheral nerve stimulation is involuntary. In a reflex action, the spinal cord along with the brain stem is responsible for the reflex movements.
  • 33. A few examples of reflex action are:  When light acts as a stimulus, the pupil of the eye changes in size.  Sudden jerky withdrawal of hand or leg when pricked by a pin.  Coughing or sneezing, because of irritants in the nasal passages.  Knees jerk in response to a blow or someone stamping the leg.  The sudden removal of the hand from a sharp object.  Sudden blinking when an insect comes very near to the eyes.
  • 34.  The whole process of reflex action involves some important components. They are receptor organs, sensory neurons, nerve center, associated neurons, motor neurons and effector neurons.  The receptor organs perceive the stimuli. They are situated on the sense organs. The afferent neurons or the sensory neurons carry the stimuli from receptors to the spinal cord. The ganglion of the spinal cord has the sensory neurons.  The spinal cord is the nerve center, where synaptic connections are formed. The associated neurons are present in the spinal cord. The ventral horn of spinal cord has the motor neurons. Effector organs are the glands and muscles that behave in response to the stimuli.
  • 35. Reflex Arc  The neural pathway that controls the reflexes occurs through the reflex arc. It acts on an impulse even before it reaches the brain. There are some stimuli that require an automatic, instantaneous response without the need of conscious thought. The following diagram shows the reflex arc pathway.  The receptor here is the sense organ that senses danger. The sensory neurons pick up signals from the sensory organ and send them through other neurons which are interconnected. It is then received by the relay neuron which is present in the spinal cord. Immediately, the spinal cord sends back signals to the muscle through the motor neuron. The muscles attached to the sense organ move the organ away from danger. In reflex actions, the signals do not travel up to the brain.
  • 36.
  • 37. Neuro Humoral Transmission in CNS  Neurohumoral transmission implies that nerves transmit their message across synapses and neuroeffector junctions by the release of humoral (chemical) messengers.
  • 38.
  • 39. Steps  1. Impulse conduction The resting transmembrane potential (70 mV negative inside) is established by high K+ permeability of axonal membrane and high axoplasmic concentration of this ion coupled with low Na+ permeability and its active extrusion from the neurone. Stimulation or arrival of an electrical impulse causes a sudden increase in Na+ conductance → depolarization and overshoot (reverse polarization: inside becoming 20 mV positive); K+ ions then move out in the direction of their concentration gradient and repolarization occurs. Ionic distribution is normalized during the refractory period by the activation of Na+ K+ pump. The action potential (AP) thus generated sets up local circuit currents which activate ionic channels at the next excitable
  • 40. II. Transmitter release The transmitter (excitatory or inhibitory) is stored in prejunctional nerve endings within ‘synaptic vesicles’ . Nerve impulse promotes fusion of vesicular and axonal membranes through Ca2+ entry which fluidizes membranes. All contents of the vesicle (transmitter, enzymes and other proteins) are extruded (exocytosis) in the junctional cleft. The release process can be modulated by the transmitter itself and by other agents through activation of specific receptors located on the prejunctional membrane, e.g. noradrenaline (NA) release is inhibited by NA (α2 receptor), dopamine, adenosine, prostaglandins and enkephalins while isoprenaline (β2 receptor) and angiotensin (AT1 receptor) increase NA release. Similarly, α2 and muscarinic agonists inhibit acetylcholine (ACh) release at autonomic neuroeffector sites (but not in ganglia and skeletal muscles).
  • 41. III. Transmitter action on postjunctional membrane The released transmitter combines with specific receptors on the postjunctional membrane and depending on its nature induces an excitatory postsynaptic potential (EPSP) or an inhibitory postsynaptic potential (IPSP).
  • 42. IV. Postjunctional activity A suprathreshold EPSP generates a propagated postjunctional AP which results in nerve impulse (in neurone), contraction (in muscle) or secretion (in gland). An IPSP stabilizes the postjunctional membrane and resists depolarizing stimuli. V. Termination of transmitter action Following its combination with the receptor, the transmitter is either locally degraded (e.g. ACh) or is taken back into the prejunctional neurone by active uptake or diffuses away (e.g. NA, GABA). Specific carrier proteins like norepinephrine transporter (NET), dopamine transporter (DAT), serotonin transporter (SERT) are expressed on the axonal membrane for this purpose. The rate of termination of transmitter action governs the rate at which responses can be transmitted across a junction (1 to 1000/sec).
  • 43. Write about GREY and WHITE MATER????
  • 44. Cranial Nerves and their functions  The peripheral nervous system is made up of all the nerves and nerves centers of the outlying or peripheral part of body  Any part of the nervous system not contained in the CNS is a component of peripheral nervous system. Or when they exist out from the CNS . The main subdivision are cranial and spinal nerve.  The PNS consist of  12 pairs of cranial nerve  31 pairs of spinal nerves
  • 45.  There are 12 pairs of cranial nerves originating from the brain  1st and 2nd cranial nerves arise from cerebrum  3rd and 4th arise from midbrain  5th and 6th arise from pons and  9th -12th arise from medulla  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.
  • 46.
  • 47. I. Olfactory nerves : The olfactory nerve transmits sensory information to your brain regarding smells that you encounter. When you inhale aromatic molecules, they dissolve in a moist lining at the roof of your nasal cavity, called the olfactory epithelium. This stimulates receptors that generate nerve impulses that move to your olfactory bulb. Your olfactory bulb is an oval- shaped structure that contains specialized groups of nerve cells. From the olfactory bulb, nerves pass into your olfactory tract, which is located below the frontal lobe of your brain. Nerve signals are then sent to areas of your brain concerned with memory and recognition of smells.
  • 48. II. Optic nerve : The optic nerve is the sensory nerve that involves vision. When light enters your eye, it comes into contact with special receptors in your retina called rods and cones. Rods are found in large numbers and are highly sensitive to light. They’re more specialized for black and white or night vision. Cones are present in smaller numbers. They have a lower light sensitivity than rods and are more involved with color vision. The information received by your rods and cones is transmitted from your retina to your optic nerve. Once inside your skull, both of your optic nerves meet to form something called the optic chiasm. At the optic chiasm, nerve fibers from half of each retina form two separate optic tracts. Through each optic tract, the nerve impulses eventually reach your visual cortex, which then processes the information. Your visual cortex is located in the back part of your brain.
  • 49. III. Oculomotor nerve The oculomotor nerve has two different motor functions: muscle function and pupil response. 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. This nerve originates in the front part of your midbrain, which is a part of your brainstem. It moves forward from that area until it reaches the area of your eye sockets.
  • 50. 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. It emerges from the back part of your midbrain. Like your oculomotor nerve, it moves forward until it reaches your eye sockets, where it stimulates the superior oblique muscle.
  • 51. Iv . Trigeminal nerve : The trigeminal nerve is the largest of your cranial nerves and has both sensory and motor functions. 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. The trigeminal nerve originates from a group of nuclei — which is a collection of nerve cells — in the midbrain and medulla regions of your brainstem. Eventually, these nuclei form a separate sensory root and motor root. The sensory root of your trigeminal nerve branches into the ophthalmic, maxillary, and mandibular divisions. The motor root of your trigeminal nerve passes below the sensory root and is only distributed into the mandibular division.
  • 52. 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. This nerve, also called the abducent nerve, starts in the pons region of your brainstem. It eventually enters your eye socket, where it controls the lateral rectus muscle.
  • 53. 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 glands  communicating sensations from the outer parts of your ear  Your facial nerve has a very complex path. It originates in the pons area of your brainstem, where it has both a motor and sensory root. Eventually, the two nerves fuse together to form the facial nerve.  Both within and outside of your skull, the facial nerve branches further into smaller nerve fibers that stimulate muscles and glands or provide sensory information.
  • 54. 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.  The cochlear and vestibular portions of your vestibulocochlear nerve originate in separate areas of the brain.  The cochlear portion starts in an area of your brain called the inferior cerebellar peduncle. The vestibular portion begins in your pons and medulla. Both portions combine to form the vestibulocochlear nerve.
  • 55. 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 stylopharyngeus The glossopharyngeal nerve originates in a part of your brainstem called the medulla oblongata. It eventually extends into your neck and throat region.
  • 56. X. Vagus nerve: The vagus nerve is a very diverse nerve. It has both sensory and motor functions, including:  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 Out of all of the cranial nerves, the vagus nerve has the longest pathway. It extends from your head all the way into your abdomen. It originates in the part of your brainstem called the medulla.
  • 57. 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.  It’s divided into two parts: spinal and cranial. The spinal portion originates in the upper part of your spinal cord. The cranial part starts in your medulla oblongata.  These parts meet briefly before the spinal part of the nerve moves to supply the muscles of your neck while the cranial part follows the vagus nerve
  • 58. 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. It starts in the medulla oblongata and moves down into the jaw, where it reaches the tongue
  • 59. Specialized function of Brain The main areas of cerebrum associated with sensory perception and voluntary motor activity are know but it is unlikely that any area is associated exclusively with only one function. Except where specially mentioned, the different areas are active in both hemispheres.
  • 60.
  • 61.
  • 62. Motor areas of cerebrum a. The precentral (motor) areas: • This lies in frontal lobe immediately anterior to the central sulcus • The cell bodies are pyramid cells (Betzs Cell) and initiate the contraction of skeletal muscles. • A nerve fiber from a Betzs cells passes downwards to medulla oblongata and descend to the spinal cord. • At special point in spinal cord the nerve impulse crosses a synapse to stimulate second neurone which terminate at the motor end-plate of muscle fibre. • The motor area at the right hemisphere of cerebrum controls voluntary muscle movement on left side of body and vice versa.
  • 63.  The neurone with this cell body in cerebrum is the upper motor neurone and the other cell body in the spinal cord is called lower motor neurone. Damage to either of these neurons may result in paralysis.  The motor area control various part like head, neck, face and fingers, feet .
  • 64. b. The premotor area :  This lies in the frontal lobes immediately anterior to the motor area .  The cells are thought to control the motor area ensuring and orderly series of movements.  For example while writing many muscles contracts but the movement must be coordinated and carried out in particular sequence. Such patterns of movement when established is described as manual dexternity .  In the lower part just above the lateral sulcus there is a motor speech area which control the movement necessary for speech. This is dominate in left hemisphere.
  • 65. c. The frontal area:  This extends anteriorly from the premotor area to include the remainder of frontal lobe .  it is large area and is more highly developed in humans than in other animals.  This is thought that the communication between this and other part of cerebrum are responsible for behavior, character and emotional state of individual.
  • 66. Sensory areas of cerebrum a. Post central (sensory ) area : • This is the area behind the central sulcus. • The sensation of pain, temperature, pressure and touch, knowledge of muscular movement and position of joint are received. • The sensory area of right hemisphere receives the impulses from left side of the body and vice versa . • The large area of face is consistent with the extensive sensory nerve supply by the three branches of trigeminal nerves.
  • 67. b. The parietal area:  This lies behind the post central area and includes the greater part of parietal lobe of cerebrum .  The function of this part is to gain and acquire the particular knowledge of the objects.  This is thought that the object can be recognized by the touch alone because of the knowledge from the past experience retained in this area.
  • 68. c. The sensory speech area :  This is situated in the lower part of parietal lobe and extends upto temporal lobe.  It is here the spoken words is perceived  It is dominated in the left hemisphere in the right handed people and vice versa.
  • 69. d. The auditory area :  This lies immediately below lateral sulcus within the temporal lobe .  The cell receive and interpret impulses transmitted from the inner ear by cochlear (auditory) part of vestibulocochlear nerves (8th cranial nerve ) . e. The olfactory (smell) area :  This lies deep within the temporal lobe where impulses from nose via the olfactory nerve (1st cranial nerves) are received and perceived.
  • 70. f. The taste area :  This is thought to lie just above the lateral sulcus in the deep layers of sensory area.  This is the area where impulses from special nerve ending in the taste buds in tongue and in the lining of cheeks, palatae and pharynx are perceived as taste. g. The visual area :  This lies behind the parietal and occipital sulcus and include greater part of occipital lobe.  The optic nerves pass from the eye to this area which receives and interprets the impulses as visual impressions.
  • 71. Other areas of cerebrum are also 1. Basal nuclei 2. Thalamus 3. Hypothalamus
  • 72. PYRAMIDAL TRACTS INCLUDES: 1.Corticospinal tract 2.Corticobulbar tract * These are aggregations of upper motor neuron. *nerve fibres travel from Cerebral cortex and terminate either in brain stem(corticobulbar) or spinal cord(corticospinal). *Transmit moter impulses that control motor functions of body.
  • 74.
  • 75.
  • 76. CORTICOBULBAR TRACT • Conduct impulses from the brain to the cranial nerves. • Fibres from the ventral motor cortex travel with corticospinal tract through the internal capsule. • The UMNs synapse directly with the LMNs located in the motor cranial nerve nuclei:- NAMELY- Oculomotor, TROCHLEAR, TRIGEMINAL, ABDUCENS, FACIAL and ACCESSORY and in the nucleus ambiguus to the HYPOGLOSSAL, VAGUS AND ACCESSORY NERVES
  • 77. CORTICOSPINAL TRACT • It originate from PYRAMIDAL CELLS in layer V of the cerebral cotex. • PRIMARY MOTOR CORTEX • SUPPLEMENTARY MOTOR AREA • PREMOTOR CORTEX • SOMATOSENSORY CORTEX • PARIETAL LOBE • CINGULATE GYRUS
  • 78. • The cells have their bodies in cerebral cotex and AXONS form the bulk of the pyramidal tracts. • The nerve axons travel from the cortex through the cerebral peduncle and into the brainstem and anterior medulla. • Here they form two prominences called PYRAMIDS OF THE MEDULLA.
  • 79. • The axons that cross over move to outer part of the medulla and form the LATERAL CORTICOSPINAL TRACT. • Whereas the fibres that remain form the ANTERIOR CORTICOSPINAL TRACT. • About 80% of axons cross over and form LCS TRACT. 20% do not cross AND form ACS TRACT.
  • 80. • Termination in spinal cord: mostly laminae 3-7, few in ventral horn and laminae 1-2; mostly innervating interneurons, although some innervation of alpha motor neurons • Neurotransmitter: glutamate and/or aspartate
  • 81. FUNCTIONS CORTICOBULBAR TRACT- -SWALLOWING -PHONATION -MOVEMENTS OF THE TONGUE -FACIAL EXPRESSION CORTIOSPINAL TRACT- -INVOLVED MOVEMENT OF MUSCLES OF BODY.
  • 82. CLINICAL SEGNIFICANCE • Damage to the Corticospinal Tracts • The pyramidal tracts are susceptible to damage, because they extend almost the whole length of the central nervous system. As mentioned previously, they particularly vulnerable as they pass through the internal capsule – a common site of cerebrovascular accidents (CVA). • If there is only a unilateral lesion of the left or right corticospinal tract, symptoms will appear on the contralateral side of the body. The cardinal signs of an upper motor neurone lesion are: • Hypertonia – an increased muscle tone • Hyperreflexia – increased muscle reflexes • Clonus – involuntary, rhythmic muscle contractions • Babinski sign – extension of the hallux in response to blunt stimulation of the sole of the foot • Muscle weakness
  • 83. • Damage to the Corticobulbar Tracts • Due to the bilateral nature of the majority of the corticobulbar tracts, a unilateral lesion usually results in mild muscle weakness. However, not all the cranial nerves receive bilateral input, and so there are a few exceptions: • Hypoglossal nerve – a lesion to the upper motor neurones for CN XII will result in spastic paralysis of the contralateral side of the genioglossus. This will result in the deviation of the tongue to the contralateral side. • Facial nerve – a lesion to the upper motor neurones for CN VII will result in spastic paralysis of the muscles in the contralateral lower quadrant of the face.