Two types of cells in the peripheral nervous system
* SENSORY NERVOUS CELLS
*MOTOR NERVOUS CELLS
Nervous
System
Central
Nervous
System
Peripheral
Nervous
System
Central Nervous
System
 Consists of brain and
spinal cord
 Interprets incoming
sensory information and
issues instructions
Peripheral Nervous
System
 Consists of nerves that
extend from spinal cord
and brain
 Serve as the
communication lines,
linking parts of the body
by carrying impulses
from the sensory
receptors to the CNS and
to the appropriate glands
or muscles
Nervous
System
CNS
PNS
Efferent
(motor
division)
Afferent
(sensory
divison)
Divisions of the Peripheral Nervous System.
Sensory Nervous System-Sends information to the
cns from internal organs and external stimuli.
Motor Nervous System- Sends information from the
CNS to organs, muscles and glands
Nervous
System
CNS
PNS
Efferent
(Motor)
division
Somatic
Afferent
(Sensory
division)
Autonomic
Types of Nerves in the
Peripheral Nervous System
 Spinal Nerves
 31
pairs
 Formed by the
combination of the
ventral and dorsal
roots of the spinal
cord
 Named according to
region of cord from
which they arise
 Cranial Nerves
 12
pairs
 Serve head and neck
 Numbered in order
 Described by name,
number, and major
function
Peripheral Nervous System
 Consists of cranial and spinal nerves
 A.
Twelve pairs and their branches
 Some are responsible for the special senses
 (what
 Other
are the special senses)
receive general sensation such as
 Touch
 Pressure
 Pain
 Temperature
 They
also send out impulses for involuntary and
voluntary muscle control
Autonomic Nervous System (ANS)
 Helps maintain a balance in the involuntary
functions of the body but allows the body to react in
times of an emergency.
 Two divisions
 Sympathetic nervous system
 Parasympathetic nervous system
 Usually the two systems work together to maintain a
balanced state or homoeostasis
 Control involuntary body functions at proper rates
Sympathetic Nervous system
 Acts in emergencies such as fight or flight
 Prepares the body to act
 Raises blood pressure
 Increases heart rate and respirations
 Slows the digestive tract.
Parasympathetic Nervous System
 Counteracts the actions of the sympathetic nervous
systems after an emergency
 Slows the heart rate and respirations
 Lowers blood pressure
 Increases activity in the digestive tract.
 Video
The Somatic Nervous System
• This is part of the PNS and is responsible for
carrying motor and sensory information to and
from the CNS.
• It is responsible for all voluntary muscle
movement with one exception. (The reflex arc)
• It is responsible for processing sensory
information.
Deep tendon reflexes
An immediate contraction when a tendon is
tapped quickly.
Involuntary- Reflex arcs
Voluntary- Happen without even thinking about it
or pain is felt. An example would be touching a hot
stove. You would automatically pull your hand away
before your brain senses pain.
Techniques
• It is best to get a patient to relax when testing reflexes.
• Try changing the position of the patient.
• Have the patient put slight tension on a muscle not
being tested
• If testing a lower extremity have the patient hook the
fingers of each hand so they can pull against each
other. Right before you elicit the reflex tell them to
pull.
Note features of the reflex:
How much hammer force was required to
obtain a contraction
The strength of the contraction
The duration of the contraction
The duration of the relaxation phase
The response of other muscles (Hyperactive)
Abnormal results
• Weak or absent response may indicate damage to
nerves outside the spinal cord. (peripheral
Neuropathy)
• Damage to motor neurons before or after they
leave the spinal cord (motor neuron disease or
muscle disease)
• Excessive response may indicate damage above
the level controlling the response.
• Different responses when compared bilaterally
may be related to a disease, localized nerve
damage or trauma.
• A positive Babinski test may indicate brain
trauma or a spinal lesion.
Motor Exam: (Myotome) This is where you will be
testing movement or motor function. This is usually
going to test major muscle groups of the upper and
lower extremities. The muscles are tested for
• mass
• muscle tone
• strength
Sensory Exam: (Dermatome) The sensory part of the
exam evaluates the sensation
• what they can feel
• This includes touch (deep and superficial)
• pain and temperature sensation
Dermatomes
Test for changes in sensation. Can use your
finger, reflex hammer, pin wheel.
All tests should be done with eyes closed
All tests should be compared bilaterally
Myotomes
Tests for difference is strength and movement
All tests should be done bilaterally
Upper extremity dermatomes
C1
Top of head
C2
Temporal & occipital regions of head
C3
Neck and posterior cheek
C4
Superior shoulder and clavicle
C5
Deltoid patch & lateral arm
C6
Lateral forearm, thumb and index finger
C7
Posterior lateral forearm & middle finger
C8
Medial forearm, ulna border, ring & little fingers
T1
Medial side of forearm & upper arm
Lower Extremity Myotome (motor)
Reflex
L1-L2 tested with resisted hip flexion
No reflex
L3 tested with resisted knee extension
Patellar reflex
L4 tested with resisted foot dorsi flexion
Patellar reflex
L5 tested with resisted great toe extension
No reflex
S1/S2 tested with plantar flexion
Achilles reflex