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By the end of this section, you will be able to:
  • Describe the structures found in the PNS
  • Distinguish between somatic and autonomic structures, including the special peripheral structures of the enteric nervous system
  • Name the twelve cranial nerves and explain the functions associated with each
  • Describe the sensory and motor components of spinal nerves and the plexuses that they pass through

The PNS is not as contained as the CNS because it is defined as everything that is not the CNS. Some peripheral structures are incorporated into the other organs of the body. In describing the anatomy of the PNS, it is necessary to describe the common structures, the nerves and the ganglia, as they are found in various parts of the body. Many of the neural structures that are incorporated into other organs are features of the digestive system; these structures are known as the enteric nervous system    and are a special subset of the PNS.

Ganglia

A ganglion is a group of neuron cell bodies in the periphery. Ganglia can be categorized, for the most part, as either sensory ganglia or autonomic ganglia, referring to their primary functions. The most common type of sensory ganglion is a dorsal (posterior) root ganglion    . These ganglia are the cell bodies of neurons with axons that are sensory endings in the periphery, such as in the skin, and that extend into the CNS through the dorsal nerve root. The ganglion is an enlargement of the nerve root. Under microscopic inspection, it can be seen to include the cell bodies of the neurons, as well as bundles of fibers that are the posterior nerve root ( [link] ). The cells of the dorsal root ganglion are unipolar cells, classifying them by shape. Also, the small round nuclei of satellite cells can be seen surrounding—as if they were orbiting—the neuron cell bodies.

Dorsal root ganglion

This micrograph shows the structure of the dorsal root ganglion. The cell bodies of the neurons and the axon bundles are also labeled.
The cell bodies of sensory neurons, which are unipolar neurons by shape, are seen in this photomicrograph. Also, the fibrous region is composed of the axons of these neurons that are passing through the ganglion to be part of the dorsal nerve root (tissue source: canine). LM × 40. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)

Spinal cord and root ganglion

This micrograph shows a magnified view of the dorsal root ganglion, showing the satellite cells and the cell bodies of sensory neurons.
The slide includes both a cross-section of the lumbar spinal cord and a section of the dorsal root ganglion (see also [link] ) (tissue source: canine). LM × 1600. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)

View the University of Michigan WebScope at (External Link) to explore the tissue sample in greater detail. If you zoom in on the dorsal root ganglion, you can see smaller satellite glial cells surrounding the large cell bodies of the sensory neurons. From what structure do satellite cells derive during embryologic development?

Another type of sensory ganglion is a cranial nerve ganglion    . This is analogous to the dorsal root ganglion, except that it is associated with a cranial nerve    instead of a spinal nerve    . The roots of cranial nerves are within the cranium, whereas the ganglia are outside the skull. For example, the trigeminal ganglion    is superficial to the temporal bone whereas its associated nerve is attached to the mid-pons region of the brain stem. The neurons of cranial nerve ganglia are also unipolar in shape with associated satellite cells.

Questions & Answers

what is lungs
Shipon Reply
what is heart beat,?
Naqeeb Reply
what functions of heart
Muthu Reply
To circulate the blood
Arshad
it pump blood to the lungs
Laura
very twiest
Shipon
what should be the nature of cell
Kashish Reply
Cells die and reproduce
Nejat
knuckle of the middle finger
James Reply
because of the gases (nitrogen, oxygen)
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why the heart is protected with that sac
Joshua Reply
To prevent collision with the lungs, lubricates the heart, protects the heart from infection in the event a peripheral organ is effected, and stabilizes the heart within the mediastinum.
Jeremiah
This app should be updated too much as there is very little information for some topics.I hope you will consider my information....
aman Reply
adenohypophysis is made up of what type of cells and what is the name of those cells?
Mannu Reply
whatpassesthroughmaleovale
armstrong Reply
motor root of the trigeminal nerve
Vandana
what is the nervous system about
Joshua
what passes through foramen ovale?
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what are the organelles of a cell
Amina Reply
muscular system
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nucleus ribosome Golgi body call membrane cytoplasm
Sabina
these are the cellular components that functions to provide energy,remove waste and cell division
Waziri
Organelles of the cell are: Mitochondria,Ribosome,golgi apparatus, nucleus, secretory granules, nuclear e t c
Khadijah
what are local hormones
Richard
Local hormones are hormones that effect the cell that released them or cells near the releasing cell and they do not circulate within the blood stream.
Jeremiah
the trachea bifurcated into how many branches on the right lung
barbie
three lobes
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Explain the normal flow of blood.
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Choolwe Reply
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idk
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1 sec not specific
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1_3seconds
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No
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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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