Thursday, March 16, 2006
Peripheral does NOT mean "of minor relevance or importance"!
Peripheral Nerves...what do they do? Where can you find them? Do they owe you any money? Let's find out the answers,shall we?
The object in question, peripheral nerves!(courtesy the University of Kansas)
The peripheral nerve system is your body's link to the outside world. It consists mostly of bundles of axons that extend from the brain and spinal cord(both of which make up the CENTRAL nervous system). The peripheral nevers from the brain are call cranial, and the ones from the spine are called spinal.All these nerves link all body parts to the CNS. The PNS has two subdivisions, but it's all the SAME thing. (wakka wakka) The Sensory aka Afferent division is nevres fibers carring messages TO the central nervous sysytem from sensory receptors anywhere on the body. The Motor or Efferent division brings impulses from the CNS to muscles and gland, also known as effector organs (as in,they EFFECT a response).
The sensory division is split into two categories. Fibers conveying information from the skin, joints and skeletal muscles, are called somatic afferent, and those bringing impulses from visceral organs are called visceral afferent fibers(visceral=ventral body cavity).
The motor division has two categories within itself. The somatic nervous sytem (soma means "body") which is composed of axons (aka nerve fibers) which we have conscious control over, and the automatic nervous sytem composed of visceral motor nerve fibers that controls glands, cardiac and smooth muscles. Guess why it's call automatic? cause we don't have to think about it! that's right,ladies and gentlemen..it happens by itself. Thus, it is sometimes called the "involuntary nervous sytem."
Look,ma! It's an automatic nervous system!(photo courtesy of the University of Delaware)
Nervous tissue is made up of two kinds of cells: supporting cells which surround and wrap more delicate neurons, and...neurons! They transmit electrical signals.
Neurons hang out with smaller cells called neuroglia. Think of them as "nerve glue". The two types of neuroglia found in the PNS are satellite cells and Schwann cells. Satellites surround the neuron cell bodies. They look like moons around a planet! Schwann cells surround and form sheaths around larger nerve fibers.
Got Spine?
(Photo coutesy www.spineuniverse.com)
What is the Peripheral Nerve System without the vetebral column? Um,a big nasty mess!
The spine aka vetebral column is about 28 inches long in an adult, S-shaped, and have five major divisions. The first 7 vertebrae are the cervical(supporting the neck), the next 12 are the thoracic, and the ones supporting the lower back are called lumbar. The book suggested something really corny to remember how many vertebrae are in each section: common meals times are at 7 am, 12 noon,and 5 pm. Corny,but it works for me! Under the lumbar, we have the sacrum, which is 5 vertebrae fused together, and the coccyx aka "tailbone", which is four fused vertebrae. The vertebral column surrounds the spinal cord, keeping it safe. And how does Mr Spine work with Mr PNS?
Remembering that the Central Nervous System includes the brain and spinal chord, from the brain projects 12 pairs of cranial nerves, and from the spinal cord, 31 pairs of spinal nerves. All of these pairs of nerves are referred to as the Peripheral Nervous System. Of the spinal nerves, 8 come from the cervical area, 12 from the thoracic, 5 from the lumbar, 5 from the sacrum,and only one from the coccyx. Each spinal nerve connects to the spinal cord by means of roots: one to the front of the spine,one to the back. The front or ventral roots have the motor fibers, and the rear or dorsal roots have the sensory fibers.
(Photo courtesy of http://www.unm.edu/~jimmy/spinal_notes.htm)
The object in question, peripheral nerves!(courtesy the University of Kansas)The peripheral nerve system is your body's link to the outside world. It consists mostly of bundles of axons that extend from the brain and spinal cord(both of which make up the CENTRAL nervous system). The peripheral nevers from the brain are call cranial, and the ones from the spine are called spinal.All these nerves link all body parts to the CNS. The PNS has two subdivisions, but it's all the SAME thing. (wakka wakka) The Sensory aka Afferent division is nevres fibers carring messages TO the central nervous sysytem from sensory receptors anywhere on the body. The Motor or Efferent division brings impulses from the CNS to muscles and gland, also known as effector organs (as in,they EFFECT a response).
The sensory division is split into two categories. Fibers conveying information from the skin, joints and skeletal muscles, are called somatic afferent, and those bringing impulses from visceral organs are called visceral afferent fibers(visceral=ventral body cavity).
The motor division has two categories within itself. The somatic nervous sytem (soma means "body") which is composed of axons (aka nerve fibers) which we have conscious control over, and the automatic nervous sytem composed of visceral motor nerve fibers that controls glands, cardiac and smooth muscles. Guess why it's call automatic? cause we don't have to think about it! that's right,ladies and gentlemen..it happens by itself. Thus, it is sometimes called the "involuntary nervous sytem."
Look,ma! It's an automatic nervous system!(photo courtesy of the University of Delaware)Nervous tissue is made up of two kinds of cells: supporting cells which surround and wrap more delicate neurons, and...neurons! They transmit electrical signals.
Neurons hang out with smaller cells called neuroglia. Think of them as "nerve glue". The two types of neuroglia found in the PNS are satellite cells and Schwann cells. Satellites surround the neuron cell bodies. They look like moons around a planet! Schwann cells surround and form sheaths around larger nerve fibers.
Got Spine?
(Photo coutesy www.spineuniverse.com)What is the Peripheral Nerve System without the vetebral column? Um,a big nasty mess!
The spine aka vetebral column is about 28 inches long in an adult, S-shaped, and have five major divisions. The first 7 vertebrae are the cervical(supporting the neck), the next 12 are the thoracic, and the ones supporting the lower back are called lumbar. The book suggested something really corny to remember how many vertebrae are in each section: common meals times are at 7 am, 12 noon,and 5 pm. Corny,but it works for me! Under the lumbar, we have the sacrum, which is 5 vertebrae fused together, and the coccyx aka "tailbone", which is four fused vertebrae. The vertebral column surrounds the spinal cord, keeping it safe. And how does Mr Spine work with Mr PNS?
Remembering that the Central Nervous System includes the brain and spinal chord, from the brain projects 12 pairs of cranial nerves, and from the spinal cord, 31 pairs of spinal nerves. All of these pairs of nerves are referred to as the Peripheral Nervous System. Of the spinal nerves, 8 come from the cervical area, 12 from the thoracic, 5 from the lumbar, 5 from the sacrum,and only one from the coccyx. Each spinal nerve connects to the spinal cord by means of roots: one to the front of the spine,one to the back. The front or ventral roots have the motor fibers, and the rear or dorsal roots have the sensory fibers.
(Photo courtesy of http://www.unm.edu/~jimmy/spinal_notes.htm)# posted by Stephan @ 7:43 PM 
Comments:
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I liked the humor involved. You got to some of the main points, but it was rather shoert and lacked descriptive images. I don't like to criticize, but I guess that's part of the class. I still think you did a good job.
Hi Stephan,
I think you do a great job each week summarizing the info in your own words. I agree with Heidi, I love your humor, it makes it fun to read your weekly blog. One thing I think you could have included to make your blog a little better is to add some info on the structure of the vertebrae and intervertebral discs. This would probably help further explain how the spinal nerves come out of the spinal column. Keep up the good work!
Melissa
I think you do a great job each week summarizing the info in your own words. I agree with Heidi, I love your humor, it makes it fun to read your weekly blog. One thing I think you could have included to make your blog a little better is to add some info on the structure of the vertebrae and intervertebral discs. This would probably help further explain how the spinal nerves come out of the spinal column. Keep up the good work!
Melissa
hey Steven,
You definately are a funny character! Everytime I read one of your blogs it blows my mind how you sum everything up in so many words. You will have to show me that trick sometime. I have a diificult time with time if you cannot tell. It takes me a good 5-10 to do my blog entries. I still hadn't completed mine when I accidently posted. I guess you forgot the structure of the vertebrae and vertebral discs, I lacked in that area also. Overall I thought you did fine. See ya tommorow
You definately are a funny character! Everytime I read one of your blogs it blows my mind how you sum everything up in so many words. You will have to show me that trick sometime. I have a diificult time with time if you cannot tell. It takes me a good 5-10 to do my blog entries. I still hadn't completed mine when I accidently posted. I guess you forgot the structure of the vertebrae and vertebral discs, I lacked in that area also. Overall I thought you did fine. See ya tommorow
Stephan, I agree with your colleagues--what a very distinctive voice!! Keep that up!! And nice job organizing things in a narrative that clearly makes sense and is original to you. Even more than the intervertebral disks is something on how neurons work--action potentials--and the different types of nervous system cells including the neuroglial cells. Keep up the oroginal style, but just check for completeness!!
LF
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