Download Spinal Nerves

Spinal Nerves
Who’s The Boss?
• The brain and spine make up the
central nervous system
• They are two primary players in
any decision, thought or
emotion that you experience in
your day
• However, the workload is not
equal
• Sometimes one of the two is
asked to do much more
Who’s The Boss?
• Much like the government of
any country, the brain and spine
handle issues that arise
• But in any country, the president
is not tasked with handling the
simple day to day matters
• As an example, the president of
the USA is not tasked with
finding a lost cat
Who’s The Boss?
• In this scenario, the brain can be
thought of as the president
• The conscious brain makes many
of the big decisions that you
have throughout the day
• An example might be when you
decided what to wear to school
today
Who’s The Boss?
• The spine functions more like local
government
• It connects the outside “people”
with the inside “government”
• When sensory information comes
in it sends it to the proper place in
the brain and when signals go out
it directs them to the proper
location in the body
• It also handles some small issues
that would take too much of your
conscious brain’s time
The Spinal Cord
• Your spinal cord is structurally
and functionally integrated with
your brain
• The spinal cord is a long tube of
nervous tissue that extends from
the base of the brain all the way
to the lumbar region of the
spine
• The way that it built and
structured tells us a lot about
the way that it works
The Spinal Cord
• The adult spinal cord measures
approximately 18 inches in length
and .5 inches in width
• You might be confused with the
length, however the spinal cord
does not run the entire length of
the spine
• It ends between L1 and L2
• The cauda equina consists of the
nerves that function below the
spinal cord in the lumbar and
sacral regions
The Spinal Cord
• Just like the spine, the spinal
nerves are named based on the
location of the nerves
• Cervical nerves are found in the
cervical section of the spine
• Thoracic nerves are in the
thoracic section of the spine
• Lumbar nerves are found in the
lumbar section of the spine
The Spinal Cord
• The actual cross sectional shape
of the spinal cord is oval
• However the dorsal side of the
spinal cord has a shallow
longitudinal groove called the
posterior median sulcus
• A much larger groove is seen on
the ventral surface is called the
anterior median fissure
Spinal Nerves
• Each spinal segment is
associated with a pair of dorsal
root ganglia
• These contain the cell bodies of
sensory neurons
• The sensory nerves connect to
the spinal cord by the dorsal
root
Spinal Nerves
• A pair of ventral roots bring
information back to the motor
neurons
• These nerves function to bring
information from the spinal
column to the outlying organs
• This allows you to control your
own body
Spinal Nerves
• The dorsal roots and the ventral
roots meet at the spinal nerve
• Two spinal nerves are associated
with each vertebrae and control
the sides of the body
• Each spinal nerve is a mixed
nerve
• A mixed nerve has both motor
neurons and sensory neurons
Naming the Nerves
• There is a specific arrangement
to the spinal nerves
• These nerves are named very
specifically to designate what
part of the body they service
• In the thoracic, lumbar and
sacral regions the associated
spinal nerve is named for the
vertebrae directly superior to it
Diagram: Sideways…
Naming the Nerves
• However this pattern changes
when referring to the cervical
nerves
• This is because the first pair of
spinal nerves pass between the
skull and C1
• In order to compensate for this,
the cervical nerves are named
after the vertebra directly
inferior to the nerve
White vs Gray
• The neurons that are in the
spine are one of two types
• Grey neural tissue is composed
of dendrites, axons and synapses
• White neural tissue is composed
of cells with myelinated axons
that connect all of the neurons
in the brain and spine
White vs Gray
• In a cross section of the spinal
cord shows that the gray matter
and the white matter are not
uniformly distributed
• The white matter is located on
the outside of the spinal cord
• The gray matter is located on the
inside of the spinal cord
Video
• https://www.youtube.com/watc
h?v=xXWsQrl1N7s
Surrounding the Spine
• The spine is sectioned off from
the other parts of the body
• The spine is sectioned off the
other parts of the body because
it helps protect the spine from
injury and infection
• Different layers of membranes
and fluid buffer the spine from
the outside world
Surrounding the Spine
• The spinal meninges are a series
of specialized membranes
surrounding the spinal cord
• It has three different layers
• The outer most layer is the dura
matter
• The middle layer is arachnoid
mater
• The innermost layer is the pia
mater
Surrounding the Spine
• Inside the layers of the meninges
there is a fluid called the
cerebrospinal fluid (CSF)
• This fluid serves many roles
• It acts as a shock absorber, a
medium for dissolved gases,
medium for nutrients, medium
for chemical messengers and
waste products
Surrounding the Spine
• A bacterial or viral infection of
the spine is called meningitis
• Meningitis causes a swelling or
inflammation of the spine
• The swelling stops the flow of
CSF creating a backup of waste,
a lack of nutrients and a loss of
functions of the nerves
Video
• http://losangeles.cbslocal.com/2
015/02/10/moorpark-couplewho-lost-daughter-to-bacterialmeningitis-hopes-their-storywill-save-lives/