Nervous system (a student reviewer)

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Review for Battery Exam
DOMINGO,JERARD LLOYD B. BSN1a

HOUSE RULES:
1. Cellphone- silent mode
2. Walang maingay
3. Walang tayo ng tayo
4. Bawal ang Mobile Legends
5. Makinig mabuti kasi may quiz
pagkatapos ng discussion.
6. BAWAL sabihin sa ibang kaklase na
nagrereview PARA MANGUNA
TAYO SA BATTERY.

Review of the
Anatomy and
Physiology
of the
Nervous system
Jerard Lloyd B. Domingo, Student Nurse
President Ramon Magsaysay State University
College of Nursing
BSN 1A

What is the
nervous
system?
The communication system, that receives
signals from any part of the body and send
commands to the different areas of the
body.

Nervous System
The nervous system is the master controlling
and communicating system of the body.
Every thought, action, and emotion reflects its
activity. Its signaling device, or means of
communicating with body cells, is electrical
impulses, which are rapid and specific and
cause almost immediate responses.

Functions of the NS
1. Receiving sensory input (RSI)
2. Integrating information (II)
3. Controlling Glands and Muscles
(CGAM)
4. Maintaining HOMEOSTASIS (MH)
5. Establishing and Maintaining
MentalActivity ( EMMA)

1. Receiving Sensory Input (RSI)
• Sensory input ay ang mga Internal (sa loob)
and external (sa labas) na stimuli (something
that arouses action or activity)
• Example ng internal and external stimuli ay ang
5 senses (smell, touch, hearing, taste, vision)
• Other form of stimuli are body position, pain,
and temperature. Other stimuli such as blood
pH (power of hydrogen), blood gases and BP
are processed at SUBCONSCIOUS LEVEL.

2. INTEGRATING INFORMATION
• The brain and spinal chord are
the MAJOR ORGANS na
nagpaprocess ng information o
sensory input at nag iinitiate ng
responses para mastore as
memory at maignore kasi hindi
sya ganun ka relevant.

3. CONTROLLING MUSCLES
AND GLANDS
 The major systems that control
the movements of muscles and
glands such as skeletal muscles
(voluntary), cardiac muscle
(involuntary), smooth muscle, and
many glands.

4. MAINTAINING HOMEOSTASIS
• the ability of the body to maintain homeostasis
depends on the ability of the nervous system to
detect, interpret and respond to changes in
internal and external conditions. Nervous
system can stimulate (excite) or inhibit (slow
down) the activities of other systems to
maintain normal environment inside and outside
of the body. The nervous system does not
work alone to regulate and maintain body
homeostasis; the endocrine system is a
second important regulating system.

5. Establishing and Maintaining
Mental Activity
• The brain is the center of mental
activity like processing
information, storage of memory,
consciousness, and thinking.

Divisions of the Nervous System
The nervous system consists of two divisions: the
central nervous system containing the brain and
spinal cord, and the peripheral nervous system
which is a network of nerves and neural tissues
branching out throughout the body.
Central nervous system (CNS). The CNS consists of
the brain and spinal cord, which occupy the dorsal body
cavity and act as the integrating and command centers
of the nervous system
Peripheral nervous system (PNS). The PNS, the part
of the nervous system outside the CNS, consists mainly
of the nerves that extend from the brain and spinal cord.

The PNS is the communication link with the
CNS and other body parts.
1. Sensory division. The sensory, or afferent
division, consists of nerves (composed of
nerve fibers) that convey impulses to the CNS
from sensory receptors located in various
parts of the body.
1.1 Somatic sensory fibers. Sensory fibers
delivering impulses from the skin, skeletal
muscles, and joints are called somatic sensory
fibers.
1.2 Visceral sensory fibers. Those that
transmit impulses from the visceral organs are
called visceral sensory fibers.

2. Motor division. The motor, or efferent
division carries impulses from the CNS to
effector organs, the muscles and glands; the
motor division has two subdivisions:
the somatic nervous system and
the autonomic nervous system.
2.1 Somatic nervous system. The somatic
nervous system allows us to consciously,
or voluntarily, control our skeletal muscles.
2.2 Autonomic nervous system. The
autonomic nervous system regulates events
that are automatic, or involuntary; this
subdivision, commonly called involuntary
nervous system, has two parts: the
sympathetic and parasympathetic, which
typically bring about opposite effects.

Enteric Nervous System
• Has both sensory and motor neurons
contained in the whole digestive tract.
• can function without the input from the
CNS and PNS. But it is normally controlled
by the ANS.
• Enteric Neurons- are sensory motor and
interneurons; they receive input from the
CNS but can also function independently.

Cells of the Nervous System
• Neurons
- are the nerve
cells, recieves
stimuli, conducts
action potentials,
and transmit
signals to other
neurons or
effector organs.

Neurons cannot perform
MITOSIS because it has no
centrosome. Therefore
neurons cannot reproduce.

Soma or cell body
• The cell body integrates synaptic input and
determines the message to be transmitted
to other cells by the axon, but that is not its
only function. It contains a single nucleus as
the source of information for GENE
EXPRESSION. Extensive Endoplasmic
Reticulum, Golgi apparatus, and
mitochondria (ORGANELLES), surround
the nucleus.

Dendrites and Axons
Dendrites (Trees)
-Receive and carry information and transmit it to
the cell body.
Axon
 Thin, cylindrical process arising from the axon
hillock. (kung saan ang axon ay lumayo ng
bahagya sa cell body).
 CONDUCTS ACTION POTENTIAL towards
the CNS and away from the CNS.
• Contain vesicles of neurotransmitter.

Other terms to consider
• Axon Hillock – the area where the axon
leaves the cell body.
• Collateral axon- formed when an axon
became branched.
• Myelin Sheath- it surrounds axons and a
highly specialized insulating material. It
prevents almost all ion movements across the
cell membrane.
• Nodes of Ranvier – gaps between myelin
sheaths.

Classification of Neurons by
Functional Role
• Motor Neurons - Control effector
organs and muscle fibers.
• Sensory Neurons - Receive sensory
stimuli from internal or external
environment; Relay them to CNS.

Categories of Neurons
1. Multipolar Neurons – have many dendrite
and a single axon. Mostly all of the neurons
in the CNS and nearly all motor neurons are
multipolar.
2. Bipolar Neurons- have two processes.
Have one dendrite and one axon. It is
located in some sensory organs (retina of
the eye and nasal cavity).
3. Pseudo-unipolar neurons – have a
single process extending from the cell
body.
This process divides into two processes. One
for the CNS and one for the PNS.

A single
process is
connected
to the cell
body.

Glial Cells
• Or neuroglia (Nerve Glue)
• Are the supportive cells of the CNS and
PNS.
• Does not conduct AP/NI.
• they are more numerous than neurons
because they retain the ability to divide.
• Enhances neuron function and maintain
normal conditions within nervous tissue.

1. Astrocytes
(Highly Branched Cell)
1. Major supporting cells of the PNS.
2. Can stimulate and inhibit the signalling
activity of neurons. (REGULATES)
3. Participate in the endothelium of blood
vessels to form a permeability barrier or
the BBB (Blood Brain Barrier) between
the blood and the CNS. (BBB)

4. Helps in neural tissue repair.
5. Helps limit the damage to neural tissue ;
however the repair process may form a
scar that blocks the regeneration of
damaged axons.
SO THEREFORE, NEURONS DOES NOT
REPRODUCE, MULTIPLY OR DIVIDE.
BUT THEY CAN REGENERATE.

Ependymal cells
(Epithelial like)
• Line the fluid filled cavities (ventricles or
canals) in the CNS.
• Some EC produces CSF (Cerebrospinal
Fluid) and others with cilia on the surface.
*cilia helps the CSF to move and flow
through the CNS.
*CSF - bathes the brain and spinal chord. It
protects the CNS because it provides a
protective cushion around the CNS.

• Ependymal cells has a specialized structures
called the CHOROID PLEXUSES which
produces the CSF.
• Hydrocephalus – accumulation of CSF in
the ventricles due to the blockage of the
opening of the 4th ventricle. This
increases pressure and dilates ventricles
causing it to become enlarged.
• T: drainage tube or “Shunt” to lessen the
high internal pressure.

3. Microglia
(small mobile cells)
• They are the immune cells of the CNS.
• They help to remove cell debris and
remove bacteria. (become phagocytic in
response to inflammation).
• They protect the CNS from infection.

4. Oligodendrocytes
(cells with processes that can
surround different axons)
• Insulating material that surrounds an axon.
It is the CNS Myelin sheaths.
• PNS
1. Schwann cells - Insulating material that
surrounds an axon. It is the PNS Myelin
sheaths.

Organizations of Nervous Tissue
• Nervous tissue varies in colour due to the location and
arrangement of the parts of neurons and glial cells.
• The Gray Matter - consists of groups of neuron cell
bodies and their dendrites, where there is a very little
myelin.
CNS
1. CORTEX – gray matter on the
surface of the brain.
2. NUCLEI - gray matter on the
deeper part of the brain.
PNS
1. GANGLION – cluster of neuron
cell bodies at PNS.

White Matter
• Consists of bundles of parallel axons with
myelin sheaths which are whitish in
colour.
CNS
1. NERVE TRACTS OR
CONDUCTION PATHWAYS
- Propagate action potentials from
one area of the CNS to another.
PNS
1. BUNDLES OF AXONS ANSD
ASSOCIATED CONNECTIVE
TISSUE THAT FORM NERVES.

Gray Matter vs. Matter
Gray matter
• Cortex
• Nuclei
• Ganglion
• GRAYISH IN COLOR.
CONSISTS OF NEURON
CELL BODY AND
DENDRITES WITH
VERY LITTLE MYELIN.
White matter
• Nerve Tracts or
Conduction Pathways
• Nerves
• WHITISH IN COLOUR
CONSISTS OF BUNDLES
OF PARALLEL AXONS
WIHT MYELIN SHEATHS.
White

Physiology of
Action Potentials
Makinig, mag
concentrate, at
magfocus.

• Cell membrane - is composed of a
phospholipid bilayer and has many
transmembrane proteins, including different
types of channel proteins that serve as ion
channels.
♠ NA+ main extracellular cation
♠ K+ main intracellular cation
• it is a semi permeable membrane which only
allows specific ions to enter the cell.
• CM is impermeable to negatively charged
particles like protein therefore protein is
isolated inside the cell membrane.

• Concentration Gradient – difference in
the concentration of a solute and a solvent
between two points divided by the
distance between two points.
Example; When K+ moves down to its
concentration gradient, it means that K+
moves from an area of higher
concentration to an area of a lower
concentration. (DIFFUSION)

Open Ion Channels (OIC)
• Daanan ng ions papasok sa Cell
Membrane. ( Cell Membrane is a semi
permeable)
• Leak channels – always open
• Voltage Gated channels - opened by
change in membrane potential.
• Chemically Gated channels- opened by
neurotransmitters.

Important Terms
1. Action Potential –constituted by the
repolarization and depolarization of the cell
membrane.
2. Muscle and nerve cells are excitable cells.
Meaning the RMP may be changed to produce an
action potential.
3. RMP – Resting Membrane potential
4. Sodium-Potassium Pump (Na+K+ Pump)
5. Depolarization- change in charge inside the cell
as the sodium enters the cell.
6. Repolarization- change in charge outside the cell
as the K+ goes outside the cell.

Resting Membrane Potential is
Generated by:
1. Greater concentration of potassium (K+)
inside the cell membrane.
2. Greater concentration of of sodium (Na+)
outside the cell membrane.
3. Greater permeability of cell membrane to
K+ than Na+ because K+ is 50-100 times
more permeable because leak channels
of K+ are more numerous than Na+.

1. Stimulus is applied to a muscle cell or
nerve cell.
2. The stimulus activates the release of
neurotransmitters that will open
chemically generated channels.
3. Sodium will briefly enter (local current)
the cell to depolarize the inside charge
of the cell resulting in a change in local
potential.
4. Change in local potential causes AP
conduction.

Open Ion Channels (OIC)
• Daanan ng ions papasok sa Cell Membrane.
• 2 types of OIC
1. Leak channels – always open in RMP
2. Gated channels
i. Voltage Gated channel – opened when there’s a
change in potential inside the cell membrane.
ii. Chemically Gated channels – opened by
neurotransmitters.

Leak Channels
• Always open.
• Ions leak across the membrane down to
their concentration gradient.
• during RMP, ions diffuse through leak
channels.
• Proteins are isolated inside the cell
membrane because it is not permeable to
the negatively charged proteins.

• There are more K+ leak channels than
Na+ leak channels.
• During RMP, leak channels are only open
and gated channels are closed.
• Sodium potassium pump- driven by ATP
(Adenosine Triphosphate) Hydrolysis. It
maintains the balance inside and outside
the cell.

Action Potentials
• An action potential is defined as an abrupt spike of
depolarization and re-polarization. This is a result of the
opening/closing of ion channels that are found only in the
axon. The cell is sitting at a resting potential of about -70 mV,
when a stimulus occurs; this stimulus may be in the form of a
electrical impulse, or a synapse with another neuron. Once the
stimulus has occurred, the ion channels open, and the polarity of
the cell changes; causing it to rise to a positive value of about 30
mV; this is depolarization.
• Once this occurs, the ion channels respond, and potassium is
allowed into the cell, this causes the cellular polarity to drop,
(repolarization) and finally, once it has past the resting potential,
it will hyperpolarize to the resting potential. The action potential
is what gives rise to synapses; and is the building block of
learning and memory.

AP CONDUCTION
1. Stimulus is applied to a muscle cell or
nerve cell hat will activate the release of
neurotransmitter that will open the CGC.
2. Na+ will briefly enter (local current) the
cell to depolarize the inside
concentration.
*Depolarize- change in membrane potential.

Strong AP Weak AP
Sodium enters the cell so that the
LP will reach the TV. The
treshhold depolarization causes
the Voltage gated channels to
open that will cause a massive
600 – fold permeability to
sodium.
Gated channels close again and
the local potential disappears
without being conducted in the
cell membrane.
• Mayroong Brief reversal of charge kaya may
depolarization at repolarization kaya may naproduce na
action potentials.
• Sodium gated channels will close, and potassium
channels will open and may nangyayaring
HYPERPOLARIZATION .

Conduction of AP

Values in Millivolts (mV)
• -70 mV the resting membrane potential.
• +30 mV the final depolarization stage
• -90 mV the Hyperpolarization Stage.
• -55 mV the Treshhold value
• 0 mV Depolarization beginning

POINTS
• NO TRESHHOLD VALUE, NO AP.
• TRESHHOLD VALUE IS MOST OFTEN
REACH AT AXON HILLOCK.
• THE AMOUNT OF CHARGE REVERSAL
IS ALWAYS THE SAME.
• NEURAL SIGNALLING IS BASED ON
THE NUMBER OF CONDUCTED AP.
• AP IS CONSTITUTED BY REPO AND
DEPO.

Resting Membrane Potential
• is the point of equilibrium at which the tendency of
K+ (potassium) to move down (Diffusion) its
concentration gradient out of the cell is balanced
with the negative charge within the cell, which tends
to attract K+ back into the cell.
• is set by the activity of leak channels.
• All gated channels are closed. (VGC and CGC)
• Resting membrane potential describes the steady
state of the cell, which is a dynamic process
that is balanced by ion leakage and ion
pumping. Without any outside influence, it will not
change. To get an electrical signal started, the
membrane potential has to change.

Myelinated Axon Unmyelinated axons
1. Faster conduction of Action
Potentials
1. Slow conduction of Action
Potentials.
Saltatory Conduction
(saltatore – “to leap”)
Continuous Conduction
-AP is generated faster because AP
tends to jump from one Node of
Ranvier to the next Node because the
Myelin Sheath allows the local current
to flow through the surrounding
extracellular fluid.
-AP tends to jump from one node to
the next.
-AP is generated by the whole axon.
- slower AP conduction because AP in
one part of the Cell Membrane
Stimulates local currents in adjacent
part of the CM.

Factors Affecting the Speed of AP
1. MYELINATION (mas maraming myelin
mas mabilis)
2. AXON DIAMETER ( mas mahaba, mas
matagal)
*Autonomic Medium Diameter Neurons conduct
AP at 2-15 m/s.
* Autonomic Large Diameter Neurons conduct AP
at 15-120 m/s.

The Synapse
• Junction where the axon of one neuron
interacts with another neuron or with cells
of the effector organ.
Example: Neuromuscular Junction is the
junction of a neuron and a skeletal muscle
fiber.

Parts of the Synapse
1. Pre-synaptic Terminal – end of a Pre synaptic
axon.
2. Post-synaptic Membrane - membrane of the Post-
Synaptic Membrane.
3. Synaptic Cleft – located at the space between the
Pre-synaptic terminal and the Post-synaptic
Membrane.

Physiology of Inhibition and
Stimulatiion

1. AP reaches the Pre - Synaptic Terminal
2. Voltage Gated Channels of Calcium open
and there is an influx of calcium inside the
cell.
3. The influx causes the release of
neurotransmitters or exocystosis
(movement out of the cells by vesicles)
from the Post Synaptic Terminal.
4. The Neurotransmitters binds with the
membrane receptors that will cause the
Chemically Gated Channels of Sodium,
Chlorine, and Potassium to open or close on
the Post Synaptic Membrane.

5. The specific ion channel willl either stay
closed or opened, depending on the type of
neurotransmitter on the Pre Synaptic
Terminal or the membrane receptor on the
Post Synaptic Membrane.
6. The Responses may become Stimulation or
Inhibition depending on the type of AP and
Neurotransmitter being released.
*When sodium channels open, Post Synaptic
cell will be depolarized. Meaning na there’s
an Local Potential that will reach a
Treshhold Value that will cause stimulation.

When Potassium and Chlorine channels are
open, the Pre-Synaptic Terminal becomes
more NEGATIVE OR REPOLARIZED
caused by hyperpolarization , that’s why
an Action potential is inhibited.
There’s no Treshhold Value reached kaya
there’s an inhibition.

Neurotransmitters
INTRODUCTION
• Neurotransmitters are chemical
messengers that transmit signals from a
neuron to a target cell across a synapse.
• Target cell may be a neuron or some other
kind of cell like a muscle or gland cell.
• Necessary for rapid communication in
synapse.
• Neurotransmitters are packaged into synaptic
vesicles - presynaptic side of a synapse.

TYPES OF
NEUROTRANSMITTERS
EXCITATORY INHIBITORY BOTH
1. Norepinephrine 1. GABA (Gamma
Amino Butyric Acid)
1. Acetylcholine
2. Glycine 2. Dopamine
3. Serotonin (generally
inhibitory)
4. Endorphins
(endogenous morphine)
MNEMONIC:EGG SAND

1. ACETYLCHOLINE (ACh)
• Released at CNS, ANS Synapses and
Neuromuscular junctions.
• It is an excitatory and inhibitory neurotransmitter.
• Used by the Autonomic Nervous System, such as
smooth muscles of the heart, as an inhibitory
neurotransmitter.
• Responsible for stimulation of muscles, including
the muscles of the gastro-intestinal system.
• Used everywhere in the brain.
• Low levels of Ach leads to Alzheimer's Disease.
• Reduction of acetylcholine receptors leads to
Myasthenia Gravis (weakness of skeletal
muscles). DOMINGO,JERARD LLOYD B. BSN1a

2. NOREPINEPHRINE
 Excitatory Neurotransmitter released at selected CNS
and ANS synapses.
 Cocaine and ampethamines increase the release of NE
and blocks the reuptake of NE, resulting in
overstimulation of post synaptic neurons.
 NE increases the amount of oxygen to your brain to
allow you to think clearer and faster, NE increases your
heart rate to allow more blood to rush to your muscles
when you need them, and NE also shuts down
metabolic processes for the time of the stressful event
so blood and energy that would normally go to the
digestive organs can focus on other parts of the body.
 Scientists refer to this event as ‘Fight or Flight’.
 Fight or flight is when our body uses NE to prepare us to
stay and work through the stressful situation (fight) or run
from it (flight).

3. SEROTONIN
• A General Inhibitory Neurotransmitter released
in the CNS synapses.
• It is involved in mood, anxiety and sleep induction.
• Schizophrenic Patients has an elevated serotonin
levels.
• Drugs that blocks serotonin such as Prozac are use
to treat depression and anxiety disorders.
• Too little serotonin has been shown to lead to
• depression, anger control etc.

4. DOPAMINE
• An excitatory and Inhibitory NT.
• Released at selected CNS synapses and
ANS synapses.
• Associated with reward mechanisms in brain.
• Generally involved in regulatory motor
activity, in mood, motivation and attention.
• Schizophrenics have too much dopamine.
• Patients with Parkinson's Disease have too
little dopamine. (depression of voluntary
motor control)

5. GABA (Gamma Amino Butyric
Acid)
• It is an inhibitory NT
• Released at the CNS Synapses
• GABA is the most important inhibitory
neurotransmitter.
• Present in high concentrations in the CNS,
preventing the brain from becoming
overexcited.
• If GABA is lacking in certain parts of the
brain, epilepsy results.
*epilepsy – excessive discharge of neurons.

6. GLYCINE
• An inhibitory NT
• Released at CNS synapses
• Glycine's inhibitory activity acts on the
motor neurons of the ventral horn of the spinal
cord and the brainstem. Under normal
circumstances, glycine provides inhibition
of muscle tone that balances the excitation of
muscle tone provided by other neurotransmitters.

7. ENDORPHINS
• An inhibitory NT
• Released at Descending Pain Pathways
• The opiates morphine and heroin bind to
endorphin receptors on Pre Synaptic Axon and
reduce pain by blocking the release of a
neurotransmitter.
• Stress and pain are the two most common factors
leading to the release of endorphins. Endorphins
interact with the opiate receptors in the brain to
reduce our perception of pain and act similarly
to drug s such as morphine and codeine.

TYPES OF
NEUROTRANSMITTERS
EXCITATORY INHIBITORY BOTH
1. Norepinephrine 1. GABA (Gamma
Amino Butyric Acid)
1. Acetylcholine
2. Glycine 2. Dopamine
3. Serotonin (generally
inhibitory)
4. Endorphins
(endogenous morphine)

Spinal Cord Reflexes
• Reflex – is an involuntary reaction or quick
reaction, in response to a stimulus applied to
the periphery and transmitted to the CNS.
• Reflex Arc – a neuronal pathway (daanan)
by which a reflex occurs. It is the basic
functional unit of the nervous system
because it is the smallest and simplest way
capable of receiving a stimulus and yielding a
response.

2 types of Reflexes
1. Stretch reflex - simpest form of reflex.
Also known as the knee jerk reflex or
patellar reflex. It occurs when the
Quadriceps Femoris muscle is stretched.
2. Withdrawal Reflex – or flexor reflex.
It removes a body part from a painful
stimulus.

Knee jerk reflex

Withdrawal Reflex

5 Basic components of Reflex Arc
1. Sensory Receptor
2. Sensory Neuron
3. Interneurons ( neurons between two
connecting neurons)
4. Motor Neuron
5. Effector Organ

Neuronal Pathways
1. Converging Pathway - two or more
neurons synapse with the same post
synaptic neuron.
- allows information to be transmitted in a
converging or one neuronal pathway.
2. Diverging Pathway – axon from one neuron
divides and synapses with more than one other
post synaptic neuron.
- It allows information to be transmitted in one
neuronal pathway to diverge into two or more
pathways.

Summations
• Within the PNS and the CNS Synapses, it
takes more than a single Action Potential to
have an effect.
• That’s why many Pre-synaptic Action
Potentials are needed in the process called
summation.
• Summation of signals in neuronal pathways
allows integration of multiple subtreshhold
local potentials. (Sama samang treshhold
value to trigger an AP).

Summation
1. Spatial Summation – when a Local
Potentials originate from DIFFERENT
LOCATIONS.
Ex: potentials originated from the Sensory
neurons and descending pathways
converged to produce an AP to an EO.
1. Temporal Summation – when local
potentials overlap in time.
Ex: A single input that fires rapidly which allows
the resting local potentials to overlap briefly.

Summation
• SS and TS can lead to stimulation or
inhibition depending on the type of
signal.
• Depending on the integration of
multiple inputs determine where the
Pre-synaptic terminal will fire an AP.

The CNS and PNS
• Brain – housed in the braincase (skull)
• Spinal chord - housed in the spinal
column (vertebral column)
• PNS – nerves and ganglia outside the
CNS .
• The PNS collects information from
numerous sources both in and out on the
surface of the body and relays it in the
CNS by means of sensory neurons.

• Motor neurons in the PNS relay
information from the CNS to muscle and
glands, in and out and maintains
homeostasis.
• Nerves of the PNS is divided into 2
groups.
1. 12 pairs of Cranial Nerves
2. 31 pairs of Spinal Nerves

Spinal Cord
• Extends from the foramen magnum at the
base of the skull and to the 2nd Lumbar
vertebra.
• The inferior end of the spinal cord and a
spinal nerves exiting there resembles a “
Horse’s Tail or collectively called the
“Cauda Equina”.
• Consists cervical spinal nerve, thoracic spinal
nerve, lumbar spinal nerve, sacral spinal
nerve and coccyx spinal nerve.

Cross-Sectional Anatomy
of the
Spinal Cord

Spinal Cord
• Cross section of the Spinal Cord
- reveals that the spinal cord consists of a
superficial white matter and deep portion
gray matter.
 White matter – myelinated axons
 Gray matter- unmyelinated axons

White Matter of the Spinal Cord
• Dorsal Column
• Ventral Column
• Lateral Column
*each column has an Ascending and Descending
Tracts.
Ascending Tracts – consists of axons that conduct
AP towards the brain.
Descending Tracts – consists of axons that conduct
AP away from the brain.

Regions in the Grey Matter
(H shaped center)
1. Grey commissure - cross bar of the H
2. Central canal –fluid filled center in the
center of spinal cord. (CSF)
3. Anterior (ventral) horns
4. Posterior (dorsal) horns
5.Lateral (intermediate) horns

SPINAL NERVES
• Arise from numerous rootlets along the
dorsal and ventral surface of the Spinal
Cord.
• When Ventral Rootlets combine, it will
form the Ventral roots.
• When Dorsal Rootlets combine, it will
form the Dorsal roots.
• When the ventral root and dorsal root
combine, it will form the spinal nerves.

The Dorsal Root contains the
ganglion (gray matter of the PNS)
contains the cell bodies of
Pseudo-unipolar sensory neurons.

SPINAL NERVES
• The cell body of psuedo-unipolar neurons
are in the dorsal root ganglion. The axons of
the pseudo-unipolar neurons originate from
the periphery to the body.
• They pass through the spinal nerves and
dorsal roots of the posterior horn of the gray
matter.
• In the posterior horn, the axons either
synapse with interneurons or pass into the
White matter and ascend or descend to the
Spinal cord.

Grey Matter of the Spinal Cord
• Posterior Horn – contains Sensory Neurons
(PU Neurons)
• Lateral and Anterior Horns of the Spinal Cord
Grey Matter contains the cell body of motor
neurons that regulates the activities of muscles
and glands.
• Anterior horn – contains the somatic motor
neurons.
• Lateral horn – contains the Autonomic neurons.
Mnemonic: SAAL

1.Dorsal Roots (afferent) – contains sensory
neurons.
2. Ventral Roots (efferent) – contains the
motor neurons.
Mnemonic: DSVM

Gray Matter and Spinal Roots

Tracts of the CNS
• Ascending Tracts (Afferent)
- consists of axons that conduct Action
Potentials towards the brain.
• Descending Tracts (Efferent)
- consists of axons that conducts Action
Potential away from the brain.

Spinal Nerves
• Each spinal nerve connects to the spinal
cord via two medial roots.
• Each root forms a series of rootlets that
attach to the spinal cord .
• Ventral roots arise from the anterior horn
and contain motor (efferent) fibers
• Dorsal roots arise from sensory neurons
in the dorsal root ganglion and contain
sensory (afferent) fibers.

Spinal Nerves
• Arise along the spinal cord and the union
of the ventral and dorsal roots.
• They contain axons both sensory and
somatic motor neurons or also called as
“MIXED NERVES".
• Also contains parasympathetic and
sympathetic axons.

Spinal Nerves
• Thirty-one pairs of mixed nerves arise from the
spinal cord and supply all parts of the body except
the head.
• They are named according to their point of issue
– 8 cervical (C1-C8)
– 12 thoracic (T1-T12)
– 5 lumbar (L1-L5)
– 5 sacral (S1-S5)
– 1 coccygeal (C0)

Spinal Nerve
Spinal nerves:
1. 8 pairs of cervical spinal nerves
2. 12 pairs of thoracic spinal nerves
3. 5 pairs of lumbar spinal nerves.
4. 5 pairs of sacral spinal nerves
5. 1 pair of coccyx spinal nerves.

Spinal Nerve
• Cervical and thoracic spinal nerves arise and leave at
corresponding vertebra .
• Because the spinal cord are shorter than vertebra column, nerve
that arise from lumbar, sacral and coccyx region of spinal cord
do not leave the vertebra column at the same level where they
exit the cord.
• The root of these spinal nerves angle inferiorly in the vertebral
canal from the end of spinal cord like wisps of hair.

Spinal Nerve

Spinal Nerve
• These root of this nerve, collectively called cauda equina.
• Typical spinal nerve has 2 connection to spinal cord;
posterior / dorsal and anterior/ ventral root.
• Posterior and anterior root unite to form spinal nerve at
intervertebral foramina.
• Since posterior root contain sensory axons and anterior
root contain motor axons, spinal nerves is classified as a
mixed nerve.
• Posterior root contain posterior root ganglion which cell
bodies of sensory neuron is located.

Dermatome
• Dermatome - is the area of skin innervated by
the cutaneous branches of a single spinal
nerve.
• C1 has no specific cutaneous distributions.
• Although there are 31 pairs of spinal nerves in
humans, there are only 30 dermatomes. The
dorsal ramus of the C1 spinal nerve usually has
no sensory root; hence the first dermatome
corresponds to C2. The sensory innervation of
the front of the head comes from the trigeminal
nerve that supplies a large area of face and
scalp, and is contiguous with the cutaneous
area of C2.

DERMATOME

Spinal Nerves
Cervical spinal nerves
• 8 Pairs
• 1st pair emerge between atlas and occipital
bone.
• The remaining emerge from the vertebral column
through intervertebral foramina.
• Spinal nerves C1 – C7 exits the vertebral canal
above their corresponding vertebra.
• Spinal nerve C8 exits vertebral canal between C7
and T1.

Cervical Spinal Nerves

Thoracic Spinal Nerve
• 12 pairs
• Exits the vertebral canal below their
corresponding vertebra.
• Emerge from thoracic vertebra
• Continuous to form intercostals nerves.

Spinal Nerves
Lumbar Spinal Nerve
• 5 pairs
• Emerge from lumbar vertebra.
• Exits the vertebral canal below their
corresponding vertebra.

Sacral and Coccyx Spinal Nerve
Sacral and Coccyx Spinal Nerve
• 5 pairs
• From the spinal cord, the root of the sacral
spinal nerve enter the sacral canal (part of the
vertebral canal).
• Sacral nerves (S1-S4) exits the vertebral canal
via 4 pairs of anterior and posterior sacral
foramen.
• Spinal nerves S5 and Co1 exits from sacral
hiatus.

Distribution of Spinal Nerve
Branches
• From the root, after passing the intervetebral foramen,
a spinal nerve divide into several branches.
• Theses branches are call rami (ramus) ; posterior
(dorsal) ramus and anterior (ventral) ramus.
• Posterior (dorsal) ramus serve the deep muscles and
skin of the posterior surface of the trunk.
• Anterior (ventral) ramus serve muscles and structure
of the upper and lower limbs and the skin of the lateral
and anterior surface of the trunk.

Plexus
• Plexus (braids) – neurons or several spinal
neve come together and intermingle
(combine).
• Spinal nerves T2-T11 does not join a
plexus, but they extend around the thorax,
between the ribs, giving off branches to
muscle and skin.
• Intercostal nerves supply muscles of the ribs,
anterolateral thorax, and abdominal wall
• Small coccygeal plexus – supplies motor
innervation to the muscles of the pelvic floor
and sensory cutaneous innervation of the
skin over the coccyx.

Plexus
1. Cervical Plexus (C1-C4)
• The cervical plexus is formed by ventral
rami of C1-C4.
• Innervates several muscles attached to the
hyoid bone, skin of the neck, and posterior
portion of the neck.
1.1 Phrenic Nerve – innervates the
diaphragm
- responsible for the contraction of the
diaphragm or our ability to breathe.

2. Brachial Plexus
• Originates from C5-T1
• 5 major nerves - ARMUM
• Supplies the upper limb and shoulder.
1. Axillary nerves – innervates two shoulder
muscles and skin over the part of the
shoulder.
2. Radial nerve – innervates all the muscles in
the posterior arm and forearm as well as skin
over the posterior surface of the arm, forearm
and hand.

Radial Nerve
• “Crutch Paralysis” – when a person uses
crutches improperly so that the weight of the
body is borne in the axilla and upper arm
rather than by the hands. The top of the
crutch can compress the radial nerve against
the humerus.
Compression of the Radial Nerve can cause
dysfunction of the Radial nerve, resulting in the
paralysis of the posterior arm and forearm muscles
and loss of sensation over the back of the forearm
and hand.

3. Musculocutaneous
• Pertains to muscle and skin
• Nerve innervates the anterior muscles of
the arm and the skin over the radial
surface of the forearm.

4. Ulnar Nerve
• Innervates two anterior forearm muscles
and most of the intrinsic hand muscles.
• Also innervates the skin over the ulnar
side of the hand.
• It can be easily damaged where it passes
the posterior to the medial side of the
elbow.
• *Funny Bone – ulnar nerve at the location
of the medial side of the body.

5. Median Nerve
• Innervates most of the anterior arm
muscles and some of the intrinsic hand
muscles. It also innervates the skin over
the radial side of the hand.

3. Lumbosacral Plexus
• Originates from L1-S4.
• 4 major nerves of Lumbosacral plexus to
support the lower limbs.
1. Obturator – innervates muscles of the
medial thigh and the skin over the same
region.
2. Femoral Nerve – innervates the anterior
thigh muscle, and the skin over the anterior
thigh , medial leg and foot.

3. Tibial Nerve – posterior thigh muscles, the
anterior and posterior leg muscles and most
of the intrinsic foot muscles.
• Innervates the skin over the sole of the foot.
4. Common Fibular Nerve – innervates the
muscles of lateral thigh and leg and some
intrinsic foot muscles. Skin over the anterior
and lateral leg and the dorsal surface (top) of
the foot.
*when the Tibial and the common fibular nerves
form together within a connective tissue
sheath, it is now called the sciatic nerve.

Plexus Origin Major
Nerves
Muscles Innervated Skin Innervated
Cervical C1-C4
Phrenic
Several Neck Muscles
Diaphragm
Neck and
Posterior Head
Brachial C5-T1 Axillary
Radial
Musculo-
cutaneous
Ulnar
Median
Two shoulder Muscles
Posterior arm and forearm
muscles (extensors)
Anterior Arm Muscles (flexors)
Two anterior forearm muscles
(flexors), most intrinsic hand
muscles.
Most anterior forearm forearm
muscles (flexors) , some
intrinsic hand muscles
Part of shoulder
Posterior arm,
forearm and hand
Radial Surface of
forearm
Ulnar side of the
hand
Radial side of the
hand

Lumbosac
ral
L1-S4 Obturator
Femoral
Tibial
Common
Fibular
Medial Thigh
Muscles (Adductors)
Anterior thigh
muscles (extensors)
Posterior thigh
muscles (flexors),
anterior and posterior
leg muscles, most
foot muscles
Lateral thigh and leg,
some foot muscles
Medial Thigh
Anterior thigh,
medial leg and foot
Posterior leg and
sole of the foot.
Anterior and lateral
leg, dorsal (top)
part of foot.
Coccygeal S5 and
Co
Pelvic floor muscles Skin over coccyx

Brain
The brain is the most complex
organ in the human body.
It produces our every
thought, action, memory, feeling
and experience of the world.
This jelly-like mass of tissue,
weighing in at around 1.4
kilograms, contains a staggering
one hundred billion nerve cells,
or neurons.

BRAIN
Consists of the:
1.Brainstem
2. Cerebrum
3.Cerebellum

1. Brainstem
• Brainstem connects the Spinal cord to the
remainder of the brain. The brainstem
consists of
1.1 Medulla oblongata (inferior)
1.2 Pons (medial)
1.3 Midbrain (superior)

Brainstem
• Brainstem consists several nuclei involved in
vital body function such as:
1. Control of HR
2. BP
3. Breathing
• Damage to the Brainstem may cause death.
But cerebrum and cerebellum damage do
not cause death.
• First two cranial nerves are in the Brainstem
(Olfactory and optic)

1.1 Medulla Oblongata
• Most inferior portion of the brainstem and
is continuous to the spinal cord and
extends to the foramen magnum to the
pons.

1.1 Medulla oblongata
• Contains ascending and descending nerve
tracts which convey signals to and from the
brain.
• MO contains discrete nuclei (nabibilang)
*Discrete Nuclei has a specific functions
1. Regulation of Heart Rate
2. Breathing
3. Swallowing
4. Vomiting
5. Sneezing
6. Balance and coordination

1.1 Medulla Oblongata
*Pyramids - two prominent enlargements
that extend the length of the medulla
oblongata.
- It is consists of Descending Nerve Tracts
which transmits action potentials from the
brain to the Somatic Motor Neurons of the
spinal cord and controls the conscious
movement of skeletal muscles.

1.2 Pons
• (ponz;bridge)
• Superior to the medulla oblongata
• Contains ascending and descending nerve
tracts, as well as several nuclei.
• *Nuclei – relay information between the
cerebrum and cerebellum.
• The pons is the functional bridge between
the cerebrum and cerebellum.

1.2 Pons
• Several nuclei of Medulla Oblongata
extend to the lower pons, so functions
such as breathing, swallowing and
balance are controlled in lower pons as
well as in the medulla oblongata.
1. Chewing and Salivation

1.3 Midbrain
• Superior to the pons
• Dorsal part of the midbrain consists of the
colliculi (hill)
*2 superior colliculi – involved in visual
reflexes and recieve touch and auditory
input.
*2 inferior colliculi – serves as major relay
centers for the auditory pathways of the
CNS.

• Example: Turning the head toward a tap on
the shoulder, a sudden loud noise, or a
bright flash of light controlled in the superior
colliculi.
• Midbrain consists of nuclei involved in
coordinating eye movements and controlling
pupil diameter (pupillary reflex) and lens
shape.
• Midbrain also contains a black nuclear mass
or the substantia nigra.
*substantia nigra - part of the basal nuclei
involved in generating general body
movements.

1.2 Midbrain
• The rest of the midbrain consists largely of
ascending tracts from the spinal cord to
the cerebrum and descending tracts from
the cerebrum to the spinal cord or
cerebellum.

Reticular Formation

Reticular Formation
• Are scattered nuclei (GM) throughout the
brainstem. It plays an important role in
regulatory functions.
• Regulating cyclical motor functions like:
1. Respiration
2. Walking
3. Chewing

Reticular Formation
• Major component of the Reticular
Activating System
*RAS – plays an important role in arousing
and maintaining consciousness and in
regulating the sleep-wake cycle.
*stimuli like: ringing alarm clock, sudden
bright lights, smelling salts, or cold
water splashed on the face arouse
consciousness.

Reticular Formation
• No visual or auditory stimuli causes
drowsiness or sleep.
• General anesthetics (anesthesia) supress
the RAS.
• Damage to the cells of Reticular Formation
can cause coma.

Cerebellum
• Or Little Brain
• Attached to the brainstem by the cerebral
peduncles.
*cerebral peduncles – these connections
provide routes of communication between
the cerebellum and other body parts.

Diencephalon
• Located between the BS and cerebrum.
• Consists of the:
1. Thalamus
2. Epithalamus
3. Hypothalamus

Thalamus
• Largest part of the Diencephalon
• Consists of cluster of nuclei that is yo-yo
shaped.
• With two large lateral parts, connected in
the center by a small interthalamic
adhesion.
• Ascending sensory inputs that goes to the
brainstem and spinal cord projects in the
thalamus.

Thalamus
• Within the thalamus ascending neurons
synapse with thalamic neurons that their
axons send to the cerebral cortex.
• Influences mood and register in an
unlocalize, uncomfortable perception of
pain.

Epithalamus
• Small area of nuclei
• It is superior and posterior to the thalamus.
• Involved in the emotional and visceral
response to odours and pineal gland.
*Pineal Gland – (pine-cone shaped)
- It influences the onset of puberty
- It influences the annual activity of animals like
Migration.
- Pineal Gland produces melatonin.

Pineal Gland
*Melatonin – inhibits the reproductive
hypothalamic releasing hormone and
Gonadothrophin releasing hormone.
- Inhibition of the hypothalamus releasing
hormone which prevents the secretion of
Reproductive Hormones LSH and FSH
from the adenohypophysis (APG).

Hypothalamus
• Most inferior part of the Diencephalon.
• contains several nuclei that maintains
Homeostasis.
• Plays a central role in:
1. Control of Body Temperature
2. Hunger and Thirst regulation
3. Sexual Pleasure, rage, fear and relaxation
after a meal.
4. Nervous Perspirations or Emotional Eating

Hypothalamus
*infundibulum (funnel) – extends from the
floor of hypothalamus to the pituitary
gland.
*Mamillary Body (Mamilla-nipple) – involved
in emotional responses to odours and
memory.
• Hypothalamus controls the secretion of
hormones from the pituitary gland.

Cerebrum
• The largest part of the brain.
*Longitudinal Fissure – divides the brain
into left and right hemispheres.
*Gyri – most conspicuous (obvious) features
on the surface of each hemisphere.
*Sulci – intervening grooves that increases
the surface area of the cerebral cortex.

Cerebrum
• Each cerebral hemisphere is divided into
lobes (named in the skullbone overlying
them).
• Frontal Lobe – control of voluntary body
function, motivation, aggression, mood,
and olfactory (smell reception.

Cerebrum
• Parietal lobe - principal center for
receiving and consciously perceiving most
sensory information, such as pain, touch,
temperature and balance.

Cerebrum
*Central Sulcus – separates the frontal and
parietal lobes.
• Occipital Lobe – recieves and perceives
visual input. And it is not separated in
other lobes.

Cerebrum
• Temporal Lobe – involved in Olfactory
and Auditory sensation and plays an
important role in memory.
• Anterior and inferior portions of the
temporal lobe was called the “psychic
cortex”
*Psychic Cortex – associated with the
functions such as abstract thought and
judgement.

*Lateral Fissure – separates the temporal
lobe and cerebellum.
- Deep within the fissure is the insula or the
5th lobe.

Sensory Functions
• The sensory input to the brainstem and
diencephalon maintains homeostasis .
• Input to the cerebrum and cerebellum
keeps us informed about our environment
and allows the CNS to control motor
functions. A small portion of the sensory
input results in perception, or the
conscious awareness of stimuli.

Ascending Tracts
• Or pathways that transmit information via
AP from the PNS to the various parts of
the brain.
• Names of ascending tracts usually begin
with the prefix “spino” meaning it begin in
the spinal cord.
• Example: Spinothalamic Tract – begins in
the spinal chord and terminates at the
thalamus.

Ascending Tracts
• Almost all neurons relaying information to
the cerebrum, terminates at the thalamus.
*Another neuron then relays the information
from the thalamus to the cerebral cortex.
Example 1: Spinothalamic Tract transmits
AP dealing with pain on the thalamus and
then to the cerebral cortex.
Example 2: Dorsal Column (WM) transmits
AP dealing with touch, position and
pressure.

BONUS FACT!
• Sensory tracts typically cross from one
side of the body in the spinal cord or
brainstem to the other side of the body.
“Therefore, the left side of the brain
recieves sensory input from the right
side of the body, and vice versa.”

Sensory Areas of the Cerebral Cortex
• Area and Cortex.
• Ascending tracts projects to the Primary
sensory areas.
*Primary sensory areas – area where
sensations are perceived.
*Primary Somatic Sensory Cortex or
General Sensory area – located in the
Parietal Lobe, posterior to the central
sulcus.

Primary Somatic Sensory Cortex
• Sensory fibers containing sensory input
such as pain, pressure, and temperature,
synapse in the thalamus, and thalamic
neurons relay them to the PSS Cortex.
• Occipital Lobe – visual cortex
• Temporal Lobe – Primary auditory cortex
• Insula – Taste area (inside the lateral
fissure)

Association Area
• Immediately adjacent to the Primary sensory
areas that is involved in the process of
recognition.
• Ex: 1.When sensory AP originating from the
retina of the eye reach the visual cortex,
when the image is perceived.
>> AP pass from the visual cortex to the
visual association areas where the present
visual experiences is compared to the past
visual experience. (Have I seen this
before?)

• On the basis of this
comparison, the VAA decides if
the visual input is recognized
and judges if the input is
significant.

Example 2.
• If you pass a man walking down the street,
hindi mo papansinin kasi sya ay stranger
at wala kang pake, pero kung pamilyar
yung taong iyon, tititigan mo ng matagal or
hihinto ka pa para maidentify kung sya ba
talaga yun.

Example 3.
• There’s a stimuli from a skeletal muscle
movement, then AP will go to the primary
somatic sensory cortex, and will go
through the somatic sensory cortex and
will go throught the somatic sensory
association area.

Somatic Motor Functions
• Involuntary movements – reflexes mediating
in the spinal cord and brainstem.
• Voluntary movements – consciously activated
to a specific goal. Voluntary movements can
be sometimes become involuntary because
once a task is learned, complex tasks
such as typing and walking, can be
performed automatically or muscle
memory.

Voluntary Movements
• Result of stimulation of the neural circuits consists of
two motor neurons.
1. Upper Motor Neurons – have cell bodies in the
cerebral cortex. Axons of the upper motor neurons
forms the descending tracts that connect to lower
motor neurons.
2. Lower Motor Neurons – have cell bodies on the
anterior horn of the spinal cord gray matter or
cranial nerve nuclei. Axons of LMN leave the CNS
and extend through the spinal nerve or cranial nerve
to skeletal muscle.
*Anterior Horn controls the somatic motor movements.

Motor Areas of the Cerebral Cortex
• Primary motor cortex are in the posterior portion
of the Frontal Lobe and Anterior Portion of the
central sulcus.
• AP conducted in the Primary Motor Cortex
controls voluntary movements of the skeletal
muscles.
• The premotor area of the frontal lobe is where
motor functions are organized before they are
initiated in the PMC.
• Therefore, when AP from sensory neurons >>
WM>> Cerebral Cortex Prefrontal area (decision
making).

Example 1
• If a person decides to take a step, neurons
of the premotor area are first stimulated
and then the determination is made there
as to which muscles must contract, in
what order and what degree. Then AP will
be passed to the PMC then passed to the
Upper Motor Neurons to Lower Motor
Neurons to initiate the action.

Fact 101
• Therefore, the prefrontal area is the
motivation and the foresight to plan and
initiate movements.
• The large size of the prefrontal area in
humans account for over emotional
complexity and our relatively well-
developed capacity to think ahead and feel
motivated.

Descending Tracts
• Away from the brain
• Corticospinal – from the cerebral cortex
and then terminate to the spinal cord.
• Cortico – means from the cerebral cortex
• 2 types of Descending Tracts
1. Direct tract
2. Indirect tract

Descending tracts
Pathway Function
Direct
Lateral Corticospinal
Anterior Corticospinal
Muscle tone and skilled
movements especially of the
hands.
Muscle tone and movement of
trunk muscles
Indirect
Rubrospinal
Reticulospinal
Vestibulospinal
Tectospinal
Movement coordination
Posture adjustment especially
during movement
Posture and balance
Movement in response to visual
reflexes

Direct Tract
• Because the UMN directly transmit AP to
LMN (in the brainstem).
• Extend directly from UMN in the cerebral
cortex to the LMN in the spinal cord ( as
similar direct tracts extends to the LMN of
the Brainstem).

Indirect Tract
• Kahit sa BS nagoriginate, these tracts are
indirectly controlled by the cerebrum,
cerebellum and basal nuclei.
• It is called as indirect tract because no direct
connection exists between cortical and spinal
neurons.
• Tracts in lateral column – are most
important in controlling goal-directed limb
movement such as reaching and
manipulating.

• Tracts in lateral column – are most important in
controlling goal-directed limb movement such as
reaching and manipulating.
• Lateral corticospinal tracts are important in
controlling the speed and precision of skilled
movements of the hands.
• Ventral column and reticulospinal Tract - most
important – most important in maintaining posture,
balance and limb position through their control of
neck, trunk, proximal limb muscles.

Direct Tract
• Lateral Corticospinal Tract - descending
tract.
1. AP from the Cerebral Cortex
2. AP from cerebral cortex descend to the
brainstem.
3. At the inferior end of the pyramids of the
medulla oblongata, the axons crossover the
opposite side of the body and continue to
the spinal cord.
4. Crossover of the axons in the Brainstem or
Spinal cord to the opposite side of the body
is a typical descending pathway.

Fact !
• Thus the left side of the brain controls
skeletal muscles on the right side of the
body and vice versa.
• UMN synapse with LMN then LMN
extends to the skeletal muscle fiber or
neuromuscular junction.

Basal Nuclei
• Group of functionally related nuclei
• Consists of the Corpus Striatum and Sustantia
Nigra.
1. Corpus Striatum – located deep within the
cerebrum.
2. Substantia Nigra –a group of darkly pigmented
spots on the midbrain.
*Basal nuclei is important in planning, organizing
and coordinating motor movements and posture.

Basal Nuclei
• Has complex neural circuits that links the
Basal Nuclei with each other with the
Thalamus, and with the Cerebral Cortex.
• These connections form several feedback
loops.
• * feedback loops – can be stimulatory or
inhibitory. These are circuits that facilitates
muscle activity, especially at the beginning of
the voluntary movement.
• E.g. Beginning to walk or rising from a
sitting position.

Inhibiting Circuits
• Inhibitory circuits facilitates the action of
stimulatory circuits by inhibiting muscle
activity in antagonists muscles.(against,
opponent.)
• Inhibitory circuits inhibit random
movements of the trunk and the limbs.
• It also decreases muscle tone when the
body, limbs, and head are at rest.

Some Basal Nuclei Disorders
• Difficulty rising from a sitting position and
difficulty initiatating walking.
• Decreased muscle tone and exaggerated,
uncontrollable movements . (Parkinson’s
Disease).
• “Resting tremor” or slight shaking of the
hands at rest.
• Parkinson’s Disease, Huntington Disease
and Cerebral Palsy.

Cerebellum
• Attached by the cerebellar peduncles.
• *cerebellar peduncles – provides route of
communication between the cerebellum and
other parts of the CNS.
• Cerebellar cortex is composed of gray matter
and has gyri and sulci.
• But the Gyri are much smaller than those of
the cerebrum.
• Consists of gray nuclei and white nerve
tracts.

Cerebellum
• Involved in maintaining balance, muscle tone, and
in coordinating fine motor movement.
• Damage to the cerebellum decreases muscle tone
and fine motor movements may become very
clumsy.(barabara)
• It is a “comparator” – a sensing device that
controls the data from two sources or the motor
cortex and peripheral structures that contains
proprioceptive neurons.
*Proprioceptive Neurons – innervates joints,
muscles and tendons and provide information
about the position of the body parts.

Cerebellum
• The cerebellum compares information
about the intended movements from the
motor cortex to sensory information about
the moving structure.
• If there’s a difference detected between
the motor output, cerebellum will send AP
to the motor neurons to correct the
discrepancy. So that the result is smooth
and coordinated movements.

Example
• Close your eyes, the cerebellar comparator
function allows you to touch your nose
smoothly and easily with your fingers. If the
cerebellar comparator dysfunctions,your
finger tends to overshoot the target organ.
*Alcohol inhibits the functioning of the
cerebellum. Kaya madalas sa mga lasing ay
very clumsy with their movements or not
smooth and fine control in motor movements.

Cerebellum
• Another function of he cerebrum and
cerebellum in learning motor skills such as
playing the piano. Once the cerebrum
and cerebellum learn these skills, the
movements can be accomplished
smoothly and automatically. (Muscle
Memory in Karate)

Other Brain Functions
• The right cerebral hemisphere receives
sensory input and controls muscle activity
in the left half of the body and vice versa.
*commissures – receives sensory
information received by one hemisphere is
shared with the other hemisphere.
*corpus callosum – largest commissure
(WM) . A broad band of nerve tracts at the
base of longitudinal fissure.

FACT!
• Left hemisphere – more analytical, more
emphasizing skills such as mathematics
and speech.
• Right hemisphere - involved in functions
such as three-dimensional or spatial
perception and music ability.

Speech
• Most people speech area is in the left
hemisphere.
• Two major cortical areas are involved in
speech.
1. Sensory speech or Wernicke area
(Parietal Lobe)
2. Motor speech area or Broca area (Frontal
Lobe)

Speech – is in the left cerebral
cortex.
Sensory Speech Area
 Wernicke Area
 Controls the
understanding and
formulating coherent
speech.
 Found in the parietal lobe
Motor Speech Area
• Broca Area
• Controls necessary
movements for speech.
• Found in the frontal lobe.
Damage to these part of areas will cause aphasia (absent of defective
speech or language comprehension).
Common cause of aphasia is stroke.
- 25-40% of stroke survivors exhibit aphasia.

Brain Waves and Consciousness
 Electroencephalogram –records brain electrical
activity or brain waves. It is used for diagnosing
brain diagnosis.
 Brain waves differ in frequency and intensity.
 Alpha Waves – observed in normal person awake
but in a quiet resting state with eyes closed.
 Beta waves – higher frequency than alpha waves
and occur during intense mental activity. During
the beginning of sleep, a rapid transition takes
place as beta rhythms to alpha rhythms.

Theta waves – usually observed in
children, usually occur in adults who
are experiencing frustration or certain
brain disorders.
Delta waves – occurs at deep sleep,
in infants and in patients with severe
brain disorders.

Memory
• The storage of memory can be divided into three
stages.
1. Working memory – stores information when
there’s an immediate performance of a task.
Lasts for only seconds to minutes and occurs
only to frontal lobe.
2. Short term memory – lasts longer than working
memory and can be retained for a few minutes to
few days. It is stored by a mechanism involving
the increased synaptic transmissions.
Susceptible for brain trauma, decreased O2,
certain drugs that affect neural function such as
General Anesthetics.

Long Term Memory
 Long term memory – through consolidation, STM is transferred to
LTM where it may be stored from a few minutes to become
permanent. 2 types of LTM;
1. Declarative Memory or Explicit Memory
- Involves the retention of facts (names, dates and places, as well as
related emotional undertones. Emotions can be a gate if the
memory is stored as a permanent or not.
2. Procedural Memory or Reflexive Memory
- Involves the development of motor skills that may lead to a long
term synaptic transmission. Only a small amount of procedural
memory can be lost over time.
*Consolidation – a gradual process of involvong the new formation of
new and stronger synaptic transmission.

LTM
• Involves long term enhancement of
synaptic transmissions.
*Memory Engrams or Memory Traces
- Involved in long term retention . Repetition
of information and associating it with
existing memories help us transfer short
term to a long term memory.

Limbic System and Emotions
• Olfactory cortex and deep cortical regions
and nuclei of the cerebrum and
diencephalon are grouped together under
the Limbic System.
• Limbic System – controls emotional
behaviour, motivational drives, mood, and
the long term declarative memory.
• Hypothalamus and the limbic system are
associated. (*hunger and thirst)

Limbic System
Hippocampus - responsible for learning
and declarative memory or consolidation
of long term memories.
Amygdala – control of emotions,
behaviour and learning.
*Kluver Bucy Syndrome - lesions in
amygdala

MENINGES

Meninges
Surrounds and protect the brain and spinal
cord.
1. Dura Mater (tough mother)- most
superficial and the thickest of all the
meninges. Consists of two layers:
a) Dural Folds
b) Dural venous sinuses

Dura Mater
a) Dural folds – extend to the longitudinal
fissure between cerebrum and
cerebellum. It holds the brain in place
with the skull.
b) Dural venous sinuses – collects blood
from the small veins of the brain and
empty into the internal jugular veins
which exits the skull.

Subdural Hematoma
*Damage to veins crossing between the cerebral
cortex and dural venous sinuses that causes
bleeding.
*Can put up pressure in the brain and can decrease
functions of the affected area.
Example; Primary motor cortex is located in the
posterior portion of the frontal lobe. Therefore,
pressure on the portion of the right primary motor
cortex in hand movements can cause decreased
function in the left hand. The frontal lobe is also
involved with mood. Thus, pressure in that area
can cause “mood changes”.

Subdural Hematoma
Subdural hematoma are common in
people over 60 because their veins are not
resilient and more easily damaged.

Dura Mater
Epidural space – space between the
dura mater and the vertebrae. It is
clinically important as the injection site for
the epidural anaesthesia of the spinal
nerves, which is often given to women
during childbirth.

2. Arachnoid Mater (spider like)
• Very thin wispy
*subdural space – space between the arachnoid
mater and pia mater. It is normally only a potential
space containing a very small amount of serous
fluid.
A needle can be introduced without damaging
the spinal cord.
*Spinal block- injecting anaesthesia in the spinal
cord.
*Spinal tap – taking a sample of CSF in the spinal
cord. CSF can be examined for infectious
agents (meningitis) or for blood (hemorrhage).

3. Pia Mater (affectionate mother)
Very tightly bound to the surface of the
brain and spinal cord.
*subarachnoid space – the space between
the pia mater and the arachnoid mater that
contains blood vessels.

Ventricles

Ventricles
Are fluid filled cavities (filled with csf)
1. Lateral ventricles (posterior,anterior,inferior) –
the ventricle in each hemisphere.
2. Third ventricle – midline cavity located in the
diencephalon between the two halves of the
thalamus and connected by holes (foramina) to
the lateral ventricle.
3. 4th ventricle – located at the base of the
cerebellum and connected to the third ventricle
through the narrow canal called the cerebral
aqueduct.

Ventricles
*Cerebral Aqueduct – connects the 4th ventricle
to the third ventricle.
The 4th ventricle is continuous to the central canal
of the spinal cord.
The fourth ventricle also opens to the
subarachnoid space through foramina in its walls
and roofs.
 flow of CSF in the ventricles:
Lateral ventricles >> foramina >> third ventricle
>>cerebral aqueduct>>4th ventricle then exits
to the central canal or to the subarachnoid
space (through foramina or in its walls and
roofs)

Cerebrospinal Fluid
The fluid that bathes the brain and spinal
cord.
It is a protective cushion in the CNS.
*Choroid Plexuses – produces CSF.
When ependymal cells form a structure
in the ventricles.
CSF flows in the subarachnoid space,
central canal of the spinal cord and the
ventricles of the brain.

Cerebrospinal Fluid
*arachnoid granulations – masses of arachnoid
tissue that penetrates the superior sagittal sinus,
dural venous sinus in the longitudinal fissure and
csf passes from the subarachnoid space into the
blood through these granulations.
CSF flow: Lateral ventricles >> foramina >>
third ventricle >>cerebral aqueduct>>4th
ventricle then exits to the central canal or
enter the subarachnoid space.
*blockage of CSF causes HYDROCEPHALUS.

CRANIAL NERVES

Number Name General function Specific function
I Olfactory Sense of smell
II Optic Sensory Visual acuity
III Oculomotor Motor,
Parasympathetic
Motor to four of six extrinsic
eye muscles and upper eyelid,.
Parasympathetic: constricts
pupil, thickens lens
IV Trochlear Motor Motor to one extrinsic eye
muscle
V Trigeminal Sensory Sensory to face and teeth;
motor to muscles of
mastication.
VI Abducens Motor Motor to one extrinsic eye
muscle

Number Name General
function
Specific function
VII Facial Sensory, motor,
parasympathetic
Sensory to taste , motor to
muscles of facial expression,
parasympathetic to salivary
and tears glands.
VIII Vestibulocochlear Sensory Hearing and balance
IX Glossopharyngeal Sensory, motor,
and
parasympathetic
Sensory to taste and touch to
back of the tongue ; motor to
pharyngeal muscles,
parasympathetic to salivary
glands.
X Vagus Sensory, motor,
parasympathetic
Sensory to pharynx, larynx
and viscera. Motor to palate,
pharynx and larynx and
Parasympathetic to viscera of
thorax and abdomen.
XI Accessory Motor Motor to two neck and upper
back muscles
XII Hypoglossal Motor Motor to tongue muscles

Systems Pathology

STROKE
SYMPTOMS:
 SEVERE HEADACHE
 LOSS OF MOTOR SKILLS
 WEAKNESS, NUMBNESS OF FACE AND
LIMBS
 DIFFICULTY WITH SPEECH AND
SWALLOWING
 VISION CHANGES
 CONFUSION, INATTENTIVENESS,
DROWSINESS, OR UNCONSCIOUSNESS
 SEIZURES

STROKE
• Or cardiovascular accident (CVA)
• Stroke refers to a condition involving the death of
brain tissue due to the disruption of vascular
supply (O2 or blood).
• 2 types of stroke:
1. Ischemic stroke - results from a thrombus.
When arteries supplying the brain are blocked
due to a thrombus (*thrombus – a clot that
develops in an artery) or an embolism (embolus –
a plug which is composed of detached thrombus
or other foreign body such as a fat globule or a
gas bubble that lodged in an artery blocking it.

STROKE
2. Hemorrhagic stroke – bleeding of
arteries supplying the brain tissue.
*Lifestyle (smoking, obesity, hypertensive,
excessive eating) is a great factor and a
high risk for being a stroke patient.

STROKE
• ATAXIA – loss of feeling of pain and
temperature in limbs and face.
• Disorientation – inability to correctly
identify time, person and place.
• Dysphagia – difficulty swallowing
• Nystagmus – involuntary eye movements
or rhytmic oscillation of the eyes.
• Short and shallow breathing and increased
BP due to patient’s anxiety.

Nervous system (a student reviewer)

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