Fundamentals of Anatomy and Physiology

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The Nervous System: Introduction, Spinal Cord, and Spinal Nerves 245


Cervical
Plexus C1–C4
Nerve supply to muscles of
the neck and shoulder. Includes
the phrenic nerve which
stimulates the diaphragm
Brachial Plexus
C5 – C8, T1
Axillary, radial, median,
musculocutaneous, and
ulnar nerves

Conus
medullaris^
Lumbar Plexus
T12, L1–L4
Femoral and
obturator nerves^
Cauda
Sacral Plexus L5, S1–S2 equina L4–

(^) Sciatic (largest
nerve in the body),
common peroneal,
and tibial nerve
C1C2 (^)
C3
C5C4
C6
C7C8 (^)
T1^
T2^
T3^
T4^
T5^
T6^
T7
(^) T8
T9^
T10^
T11^
T12^
L1^
L2^
L3^
L4^
L5^
S1^
S2
S4S3
S5
Cervical
spinal^
nerves
Thoracic
spinal
nerves
Lumbar
spinal
nerves
Sacral
spinal
nerves^
Coccyx
spinal ®
nerve Learning (1)
Cengage ©
Figure 10- 10 The names and emergent levels of the 31 spinal
nerves.


Summary Outline



  1. The peripheral nervous system (PNS) consists
    of the afferent peripheral system (sensory neurons) and
    the efferent peripheral system (motor neurons).


Introduction.


  1. The nervous system is the body’s control center and
    communication network.^

  2. It shares in the maintenance of homeostasis with
    the endocrine system.


General Organization



  1. The central nervous system (CNS) consists of the
    brain and spinal cord.
    3. The efferent peripheral system can be subdivided into
    the somatic nervous system, which sends sig-nals to
    skeletal muscles, and the autonomic nervous system
    (ANS), which sends signals to cardiac and smooth
    muscles and glands.^
    4. The ANS has two divisions: the sympathetic
    division,- which stimulates and speeds up activity,
    and the parasympathetic division, which restores or
    slows down certain activities but stimulates the
    body’s vegetative activities.

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