NROLecture2.docx

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Published on 1 Aug 2012
School
University of Guelph
Department
Neuroscience
Course
NEUR 4000
Professor
NROB60 Study Package: Week 2
Homira Osman
Week 2: Lecture
May 13, 2008
Lecture Topics
Lecture II
Readings: The Peripheral Nervous System (Pages 172, 173); The Cranial Nerves (Pages 173,
232, 233); The Meninges (Pages 173, 174); The Ventricular System (Pages 174, 213);
Development of the Nervous System (Pages 180 to 187)
Lecture Summaries [L2]
- The nervous system consists of two
divisions: CNS & PNS
- Two parts of the CNS are the brain and the
spinal column
- The brain consists of the cerebellum, the
cerebrum, and the brain stem
- All parts of the nervous system other than the
brain and spinal cord comprise the peripheral
nervous system (PNS)
- The PNS consists of the nerves and nerve
cells that lie outside the CNS
- 31 pairs of nerves leave the spinal cord
- Each nerve consists of incoming sensory
fibers and outgoing motor fibers
- Fibers divide into spinal roots where they
attach to the cord
- The PNS has two parts:
o Somatic PNS
All spinal nerves that innervate
the skin, the joints, and the
muscles that are under voluntary
control are part of the somatic
PNS
The somatic motor axons, which
command muscle contraction,
derive from motor neurons in the
ventral spinal cord
The cell bodies of the motor
neurons lie within the CNS
Their axons are mostly
in the PNS
The somatic sensory axons,
which innervate and collect
information from the skin, muscles, and joints, enter the spinal cord via the dorsal
roots
The cell bodies of these neurons lie outside the spinal cord in clusters called the
dorsal root ganglia
There is a dorsal root ganglion for each spinal nerve
o Somatic includes all spinal nerves that innervate:
The skin
The joints
The muscles under voluntary control
o Visceral PNS
Also called involuntary, vegetative, or autonomic nervous system (ANS)
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NROB60 Study Package: Week 2
Homira Osman
Consists of the neurons that innervate the internal organs, blood vessels,
and glands
Visceral sensory axons bring information about visceral function to the
CNS
Pressure and oxygen content of blood in the arteries
Visceral motor fibers command:
Contraction and relaxation of muscles that forms the walls of
intestines and the blood vessels (called smooth muscles)
Rate of cardiac muscle contraction
Secretory function of various glands
Examples: Blushing, butterflies in stomach, control of blood pressure
o Visceral also referred to as the Autonomic or involuntary
nervous system (ANS)
o Innervate the:
Internal organs
Blood vessels
Glands
- Visceral sensory axons bring information about visceral function to the CNS
- Afferent and Efferent Axons
- Afferent
o Axons of the PNS bringing information INTO the CNS are afferents
o Somatic sensory axons enter through the dorsal roots (Afferent)
o Cell bodies lie outside the CNS in clusters called dorsal root ganglia
o One dorsal root ganglion for each spinal nerve
- Efferent
o Axons that emerge FROM the CNS to innervate the muscles and glands are efferents
o Somatic motor axons (control of muscle contraction) derive from motor neurons in the
ventral spinal cord (Efferent)
o Cell bodies
lie within the
CNS
o Axons are in
the PNS
- The Cranial Nerves
- 12 pairs
- Arise from the brain
stem
- Innervate (mostly) the
head
- Each nerve has a
name and a number
- Some are part of the
CNS (contained solely
within the central
nervous system)
o Others are
part of the
visceral PNS
- Many carry a complex
mixture of axons that
perform different
functions
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NROB60 Study Package: Week 2
Homira Osman
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