I
have recently been studying hands on work that is focused on the nerve,
artery and veins' affect on surrounding tissue and structure. With that
I have spent more time thinking about the nervous system. I had not yet
formulated a clear picture of what lies below the surface of my own
skin, or my clients, other than muscles, connective tissue and bones.
There has, been a mystery visual in my mind where the nervous system was
concerned. I can see the definition of muscle and the peeking of veins
through my skin but I cannot see my nerves directly.
When I was 17, I shattered my left
elbow and crushed the ulnar nerve. I was told I would never use my arm
again. I was in a cast for 6 months and had very little sensation or
use of my arm for almost a year. I was pricked with electrified needles
to determine the extent of the damage, but I never understood
what they were testing or how my nerves worked. My right arm had
learned how to do everything and I continued to use my left arm
minimally until I started yoga with a confident teacher when I was 23.
When I was in my early 3o's I had nerve pain associated with a bulging
disc in my neck. Very painful! And very hard to discern where it was
coming from (the pain would move and change) and how to heal it. It took
two years of treatment to find balance in my system again.
My
knowledge of nerves is very basic, I apologize for my limitations. And
scientific understanding is forever changing and often incomplete. But
lets take a look at the basic overall structure. First, there is the
brain(cerebral cortex, cerebellum,and brain stem) and spinal cord.
Branching out of the brain stem there are 12
cranial nerves innervating the face(eyes, ears, tongue). Cranial nerve
10, the vagus nerves, a parasympathetic nerve, innervates the heart and
digestive organs. Threading out of the spinal cord and
vertebral column are 8 cervical nerves, 12 thoracic nerves, 5 lumbar
nerves, 5 sacral nerves and 1 coccygeal nerve. A single nerve combines
with other nerves above and below to form plexuses, creating thicker
branches then branching off again to travel through the body. Look at
the picture above to see the branching out of the central line of the
brain stem and spinal cord and the weaving through the whole body. The
nerves travel along with the arteries and veins in bundles that run
between muscles, dive deep into the cells of the bone and surface to
innervate the skin. Small branches innervating the arteries, veins and
the nerves themselves.
The cervical spine has 8 spinal nerves
branching off the spinal cord and exiting out through the vertebral
column. There are 7 cervical vertebra and the nerves begin exiting the
spinal cord between the skull and the 1st vertebra(called the altas).
Nerves c1-c5 form the cervical plexus that branch to innervate the face, scalp and neck. The phrenic nerve, a branch off the cervical plexus, innervates the diaphragm and pericardium.
The brachial plexus which emanates from the lower cervical vertebrae and 1st thoracic nerve (nerves C5,c6, c7,c8 & t1), travels under the clavicle and down the length of the arm through five main branches
(median, ulnar, radial, musculocutaneous, palmar digital) and many many smaller branches.
The nerves innervate the muscles, skin and the many tissues of the arm.
The lumbar plexus is formed by the 12th thoracic nerve and some of the lumbar nerves( nerves T12, L1, L2, L3, L4). The
sacral plexus is formed by the lowest lumbar nerves and sacral
nerves(nerves L4, L5, S1, S2, S3, S4). Some don't distinguish the two
and consider the Lumbosacral one plexus. From the
lumbar
plexus, the ilio- hypogastric and ilio- inguinal circumnavigate the
torso and innervate the outer hip, front of hip and groin. Additionally
from the lumbar plexus the femoral nerve innervates the front of the the
hip and thigh. The sacral plexus with the biggest and longest nerve in
our body, the sciatic nerves, as well as other nerves from the sacral
plexus (common peroneal, tibial nerve) innervate the back of the hip and
leg.
The brain and spinal cord are protected by the bones of the the skull
and vertebral column. The three outer layers of the brain and spinal
cord; dura mater, arachnoid mater and pia mater are called the meninges.
Cerebral Spinal Fluid circulates between the pia and arach
-noid
layers and in the ventricles within the brain. The meninges and the
cerebral spinal fluid provide protection for the brain and spinal cord.
The CSF is created in the choroid process and reabsorbed in the blood
stream, provides immune support, elimination of waste and regulation of
blood flow in the brain. CSF flows around and within both the brain and
spinal cord.
The nervous system sends signals towards the body as motor signals
creating an effect in the tissue/muscle and receives information in the
brain/spinal cord as sensory signals(listening and feedback).
Neurons(nerve cells) communicate with each other in the brain and down
the spinal cord as the Central Nervous System. And communication from
the spinal cord to the rest of the body as the Peripheral Nervous
System. The nervous system affects conscious movement as well as
unconscious. The motor and sensory fibers work together in a complex
communication system. Specialized nerve endings in the skin sense
touch, temperature, and pressure. Nerve endings in muscle, tendon and
joints are also specialized for proprioception, stretch, pain, and
force. Sensory fibers in the organ tissue monitor the function of the
organs. The listening and responding of the nervous system is quite
complex. Think about how many needs are taken care of, conscious and
unconscious; hunger, digestion, temperature control, heart beat, blood
pressure, going to the bathroom, procreating, and then there is
love..... how does science explain that, really?
As the nerves leave the spinal cord, the nerve roots form branches for
superficial nerves (skin and superficial layers), spinal nerves (muscle,
fascia, bone) and in front of the vertebral column the branches form
the sympathetic ganglion and chain for the sympathetic nervous system.
There are many nerve plexuses which innervate the organs with fibers
coming from the sympathetic chain and fibers coming from the
parasympathetic nerves(i.e. vagus nerve)
The cardiac plexus, the celiac plexus, mesenteric plexuses, coccygeal
plexus, and many other nerve complexes serve the organs. Looking at the
amount of nerve tissue in the abdominal cavity, and how highly
innervated and sensitized the area is, we can see a deeper level of the
nervous system. In yoga the bigger nerve plexuses are related to
chakras. The chakras are energy centers that hold emotion, behavior
patterns and the understanding of spiritual maturity. In chinese
medicine the organs relate to the five elements which that govern our
body, our emotions and how we balance in the cycles of life. Its
interesting to see this information was understood and used in healing
before dissections and modern science.
Cranial nerves/Vagus Nerve
The
Sympathetic nervous system, Parasympathetic nervous system and Enteric
nervous system are components of the Autonomic Nervous System(ANS). The
ANS is part of the peripheral nervous system which governs the internal
organs and is regulated by the hypothalamus. Thoracic and lumbar nerve
branches form the Sympathetic nervous system(sympathetic ganglion and
chain). Cranial and sacral nerve branches form the Parasympathetic
nervous system. The Vagus Nerve is the largest cranial nerve in the
parasympathetic nervous system and regulates heart, lungs, digestion,
glands, immune function but has an even larger sensory function(80-90%)
from those same areas.
The Enteric Nervous System is formed from
sympathetic, parasympathetic and sensory fibers and resides in the wall
of the entire gastrointestinal track from our mouth to our anus. The
actions of digestion; taking food in, breaking down fats, sugars,
proteins; distributing and absorbing the nutrients; eliminating what
isn't needed.
Enteric Nervous System
The
Sympathetic system helps with our initiation, our creativity, our
strength and yes in emergencies, our ability to get out of danger. The
Parasympathetic system conserves energy and finds efficiency in our body
systems and emotions. The Enteric nervous system(ENS), with as many
neuron as the spinal cord, communicates with the brain and spinal cord
and can also act autonomously when needed. Seratonin is created in the
enteric nervous system, more than in the brain.
There is interesting
work with the GAPS diet and autism/add/adhd that addresses the affects
of gastro-intestinal balance on the severity of symptoms. And a study
relating high seratonin levels in the ENS to irritable bowel syndrome.
Whats interesting to me is the brain and organ relationship, the neural
and hormonal relationship.
The hypothalamus, within the Nervous
and Endocrine Systems and closely related to the Limbic System, works
with the pituitary gland to marry the nervous and endocrine systems
through neural/hormonal/neurohormonal regulation.
The Endocrine system regulates hormone function: everything from
metabolism, blood sugar balance and sexual development. Together with
the Nervous system, the body's system are constantly tuned to adapt to
our needs. Homeostasis becomes the driving force in the hypothalamus.
The Limbic System is a set of structures in the brain that support
emotional and behavioral reactions, motivation, memory and bonding.
Memory and emotion may
