Basic Training Series: Nervous System: Peripheral Nervous System

Here's another quickie post on the Nervous System focusing on the Peripheral Nervous system.

Quick facts:

- All spinal and cranial nerves transmit information to the CNS
- 12 cranial nerves are all specialized. Some only send info, some only receive info and some are mixed

    I     - Olfactory
    II    - Optic
    III   - Oculomotor
    IV   - Trochlear
    V    - Trigeminal
    VI   - Abducens
    VII  - Facial
    VIII - Auditory
    IX   - Glossopharyngeal
    X    - Vagus
    XI   - Accessory
    XII  - Hypoglossal

- 31 pairs spinal nerves are mixed afferent and efferent

- Spinal nerves are formed by the joining of dorsal and ventral roots and contain somatic and autonomic motor and sensory nerve fibers

- Fibers of the anterior divisions or ventral rami supply the antero-lateral parts of the trunk and limbs

• - For the most part are larger than the posterior division/dorsal rami
• -Fibers extend to the limbs to form PLEXUSES.

• Cervical 
• Located from C1-C4
• Brachial plexus: 
• Located in axillary region
• Redistributes fibers to the major nerves of the upper extremites
• Median
• Ulnar 
• Radial 
• Axillary
• Musculocutaneous
• Lumbosacral plexus:
• Located in the lower abdominal cavity and pelvis
• Redistributes the fibers to the major nerves of the lower extremities
• Femoral
• Obturator
• Sciatic
• Tibial
• Peroneal

- Fibers of the posterior divisions or dorsal rami 

• Carry visceral motor, somatic motor, and sensory information to and from the skin and deep muscles of the back
• Are distinct from each other
• Innervate a narrow strip of skin and muscle along the back at the level from which the ramus leaves the spinal nerve

Well, that's good for now. Lots of info to process but very pertinent. 

Questions? Comments? Let me know.

Will

Basic Training Series: Nervous System: Central Nervous System

The Nervous System has 3 main divisions. They are:

- Central Nervous System
- Peripheral Nervous System
- Autonomic Nervous System (which has 3 sub-divisions: 1) Sympathetic 2) Parasympathetic 3) Enteric)

In this post, I will summarize the CENTRAL NERVOUS SYSTEM (CNS).

The CNS is composed of the brain and spinal cord.

Briefly about the brain....

- evolved from 5 vesicles in the cranial section of the neural tube
- vesicles are bilateral, mostly symmetrical and specialized

- 5 vesicles are:

• Cerebral Hemisphers
• Diencephalon
• Mid Brain
• Pons
• Medulla
• *Cerebellum (should be 6th region)

- interconnected by a 4 chamber ventricular system with connecting aqueduct 

Briefly about the spinal cord....

• thin, cylinder like structure
• attached to the brain 
• 5 sections with 31 segments 
• Cervical (8 segments)
• Thoracic (12 segements)
• Lumbar (5 segments)
• Sacral (5 segments)
• Coccygeal (1 segement)
• Each segment has a pair of spinal nerves
• transmission of sensory information to the brain
• regulation of motor and autonomic functions

QUICK OBSERVATIONS:

1) The brain is VERY COMPLEX. Just knowing those 6 regions will take some time but basically it IS the control center of the body. My friend, Peter, likes to call it the President of the body. It's not so much a king because others systems have a lot of input and say of what happens with the body but in the end the President makes the decisions along with input from others. 

2) The spinal cord is the super information highway of the nervous system, and it also mediates motor and autonomic functions; but it still has to answer to the brain in the final say so. 

Well, thats enough. Just wanted to keep these short and sweet. 

I'd love to hear from you with questions or comments. 

In mind, body and spirit,

Will