Joe Pistack MS/ED
 The
brain, the
spinal cord and the
peripheral nervous
system work
together as a
communication
system.
 In
the absence of spinal cord function, there
is no sensory activity present.
 Person
 Lack
cannot feel any type of sensation.
of voluntary motor activity, cannot
move.
 Continuation
brain stem.
of the
 Tube
like structure,
located within the
spinal cavity.
 17
inches long and
extends from the
foramen magnum to
the level of the first
lumbar vertebrae.
 Lumbar
puncturea hollow needle is
inserted into the
subarachnoid space
between L3 and L4.
A
sample of
cerebrospinal fluid
is withdrawn,
sample is analyzed
for elevated
glucose, protein,
bacteria and WBC’s.
 Gray
matter-of the
spinal cord is
located in the
center and shaped
like a butterfly.
 Two
projections of
gray matter are the
dorsal (posterior)
horn and the ventral
(anterior) horn.
 Central
canalopening or hole that
extends the entire
length of the spinal
cord.
 Cerebrospinal
fluidflows from the
ventricles in the
brain through the
central canal into
the subarachnoid
space.
 White
mattercomposed
primarily of
myelinated axons.
 Grouped
together
into nerve tracts.
 Ascending
Tracts-carry information from the
periphery, up the spinal cord, and toward the
brain.
Ex.- spinothalamic tract carries sensory
information for touch, pressure and pain.
 Descending
tracts-carries information from
the brain, down the spinal cord, and toward
the periphery.
 Ex.-motor tracts
 Decussation-
the
crossing over from
one side to the
other.
 Most motor tracts
decussate at the
level of the brain
stem.
 Most sensory tracts
decussate in the
spinal cord and
travel up the spinal
cord to the brain.
 Quadriplegia-paralysis
of all four extremities
caused by the severing of the spinal cord at
the neck region.
 Usually
caused by an injury where the neck is
compressed or bent excessively.
 Paraplegia-paralysis
of the lower extremities,
person has use of upper extremities.
 The
spinal cord serves three main functions:
 Sensory pathway
 Motor pathway
 Reflex center
 Sensory pathway-spinal cord serves as a
pathway for information traveling from the
periphery to the brain.
 EX.-pick
your finger-information ascends the
spinal cord to the brain where you experience
the sensation.
 Motor
Pathway-spinal cord provides a
pathway for information coming from the
brain and going to the periphery.

Ex.-kicking a football-information needs to travel
from the brain, down the spinal cord and to the
muscles of the leg and foot.
 Reflex
center-the spinal acts as a major
reflex center.

Ex. When you stick your finger, you automatically
withdraw it from the object that you picked it
with.
 Reflex-
involuntary response to a stimulus.
Ex. Touch a hot surface, pull hand away.
 Patellar
or knee-jerk reflex-in response to a
tap on your kneecap, your lower leg quickly
and involuntarily pops up.
 Reflex
arc-nerve pathway involved in a
reflex.
 Four components of a reflex arc:
 (1) Receptor-area is stimulated.
 (2) Afferent or sensory neuron-nerve impulse
is carried by the sensory neuron to the spinal
cord.
 (3) Efferent or motor neuron-nerve impulse is
carried by a motor nerve to the muscle.
 (4) Effector organ-the stimulated organ will
move.
 Reflexes
help to regulate body function.
 Some
reflexes are used for diagnostic
purposes.
 Abnormal
reflexes of the CNS may indicate
lesions, tumors, or other neurological
diseases such as MS
 Pupillary
reflex-regulates the amount of light
that enters the eye.
 Bright
light directed into the eye, muscles
that control pupillary size constrict.
 Baroreceptor
reflex-when blood pressure
changes, these reflexes cause the heart and
blood vessels to respond in a way that
restores blood pressure to normal.
 Babinski
reflex- stroking the lateral sole of
the foot in the direction of heel to toe with a
hard blunt object.
 In
an adult, if the response is curling of the
toes it is negative or normal.
 An
abnormal response is dorsiflexion of the
big toe, with fanning or the spreading of the
other toes. Could be a sign or a lesion or
damage to the spinal cord.

Peripheral nervous system-consists of the nerves
and ganglia located outside the CNS.

Nerves are classified as follows:

Sensory nerves-composed only of sensory
neurons.

Motor nerves-composed only of motor neurons.

Mixed nerves-contains both sensory and motor
neurons.
 Classified


in two ways:
Structurally-by parts.
Functionally-according to what they do.
 Structurally-divides
the nerves into the
cranial and spinal nerves.
 Twelve
pair of cranial nerves, each has a
specific number, designated by a roman
numeral, and a name.

Carry sensory information for the special senses:
smell, taste, vision and hearing.

Carry sensory information for the general senses:
touch, pressure, pain, temperature and
vibration.

Carry motor information that results in the
contraction of the skeletal muscles.

Carry motor information that results in the
secretion of glands and contraction of cardiac
and smooth muscle.
I
Olfactory
 A sensory nerve that
carries information
from the nose to
the brain.
 Concerned with the
sense of smell.
 Damage to this
nerve may result in
loss of sense of
smell.
 II
Optic nerve
 sensory nerve that
carries visual
information from
the eye to the
brain, specifically
the occipital lobe of
the cerebrum.
 Damage to this
nerve causes
diminished eye site
or blindness.
 III-Oculomotor
 primarily
a motor
nerve that causes
contraction of the
extrinsic eye
muscles, thereby
moving the eyeball
in the socket.
 raises the eyelid
and constricts the
pupils of the eye.

III Oculomotor

Damage to this nerve interferes with raising the
eyelid, results in ptosis (drooping of the eyelid).

Compression of this nerve interferes with the
ability of the pupil to respond to light.
(sluggish pupillary response)
With severe compression, the pupil may become
fixed and dilated.
 IV-
Trochlear
 Primarily a motor
nerve that
innervates one of
the extrinsic
muscles of the
eyeball, helps to
move the eyeball.
 Damage
may cause
double vision or
inability to rotate
the eye properly.
 V-Trigeminal
 mixed
nerve with three branches supplying
the facial region.
 Two sensory branches carry information
regarding touch, pressure and pain from the
face, scalp, eye, and teeth to the brain.
 Ophthalmic branch detects sensory
information from the cornea.
 If cornea is touched, motor fibers will
respond by eliciting blinking or secretion of
tears.
 Both
the trigeminal
and facial nerves
participate in the
corneal reflex.
 The motor branch
innervates the
muscles of
mastication.
 Nerve damage
causes a loss of
sensation and
impaired movement
of the mandible.
 Trigeminal
neuralgia or tic douloureuxinflammation of the trigeminal nerve.
 Pain
may be triggered by eating, shaving, or
exposure to cold temperatures.
 VI-
Abducens
 Primarily a motor
nerve, controls eye
movement by
innervating only one
of the extrinsic eye
muscles.
 Nerve damage
prevents a lateral
rotation of the eye
At rest the eye
drifts medially,
toward the nose.
 VII-Facial

A mixed nerve that performs mostly motor
functions.
 Called
the nerve of facial expressions.
Allows us to smile, frown, and make other
faces.
 Stimulates
 Sensory
the secretion of saliva and tears.
function is taste.
 If
the facial nerve
is damaged, facial
expression is
absent on the
affected side.
 This condition is
Bell’s Palsy.
 One side of the
face sags while the
other side looks
normal.
 Cosmetically,
this
condition is very
distressing.
 Condition
responds
well to steroid
therapy.
 VIII-
Vestibulocochlear
A
sensory nerve that carries information for
hearing and balance from the inner ear to
the brain.
 The
vestibular branch of this nerve is
responsible for equilibrium, or balance and
the cochlear branch is responsible for
hearing.
 Damage
to this nerve may cause loss of
hearing or balance or both.
 IX
Glossopharyngeal
A
mixed nerve that carries taste sensations
from the posterior tongue to the brain.
 Motor
fibers stimulate the secretion of
salivary glands in the mouth.
 Other
motor fibers innervate the throat and
aid in swallowing.
 This
nerve is
associated with
the gag reflex.
 Loss
of the gag
reflex places you
at risk for choking.
 Sensory
function is
to regulate BP
X
Vagus
A
mixed nerve that innervates the tongue,
pharynx, larynx, and many organs in the
thoracic and abdominal cavities.
 Nerve
damage causes hoarseness or loss of
voice, impaired swallowing, and diminished
motility of the digestive tract.
 Sensory
fibers also participate in the
regulation of BP.
 XI
Accessory
 Primarily
a motor nerve that supplies the
sternocleidomastoid and the trapezius
muscles.
 Controls
the movement of the head and the
shoulder regions.
 Nerve
damage impairs the ability to shrug
your shoulders.
 XII
hypoglossal
 Primarily
a motor nerve that controls
movement of the tongue.
 Affects
 Nerve
speaking and swallowing activities.
damage causes the tongue to deviate
toward the injured side.
 Thirty-one
pairs of spinal nerves emerge
from the spinal cord.
 Each
pair is numbered according to the level
of the spinal cord from which it arises.
 The
8
31 pairs are grouped as follows:
pairs of cervical nerves.
 12
pairs of thoracic nerves.
5
pairs of lumbar nerves.
5
pairs of sacral nerves.
1
pair of coccygeal nerves.
 Cauda
equina“horse’s tail”area where
the lumbar
and sacral
nerves exit
from the
vertebral
column.
 Plexuses-points
where nerve fibers converge
together.
 Three



major nerve plexuses:
Cervical plexus
Brachial plexus
Lumbosacral plexus
 Each
plexus will sort out the fibers and send
them to specific parts of the body.
 Cervical
plexus-(C1 to C4): fibers from the
cervical plexus supply the muscles and skin
of the neck. Stimulate the contraction of
the diaphragm.
 Brachial
plexus-(C5 to C8, T1): supply
muscles and skin of the shoulder, arm,
forearm, wrist, and hand.
 The
axillary nerve can be damaged with
crutch walking. Patient should be taught not
to put weight on the plexus or it will cause
crutch palsy.
 Lumbosacral
plexus- (T12, L1, to L5, S1 to
S4): gives rise to the nerves that supply the
muscles and skin of the lower abdominal
wall, external genitalia, buttocks, and lower
extremities.
 Sciatic
nerve-longest nerve in the body,
arises from the lumbosacral plexus.
 When
the sciatic nerve is inflamed, it causes
intense pain in the buttock and posterior
thigh region.