Spinal Nerves Contain Both Sensory
and Motor Fibers That Supply a
Specific Area of the Body
The spinal nerves are all mixed nerves. The cell bodies
of sensory neurons lie in the posterior root ganglia (dor-
sal root ganglia), while those of motor neurons lie in the
anterior horns of the spinal cord (see Figure 7.12c). After
emerging from the spinal cord, many spinal nerves di-
vide into several branches that form networks of neurons
called
plexu ses
(singular is plexus; Figure 7.19 ). After
the nerves pass through the plexus, the emerging nerves
carry neurons from several adjacent spinal segments.
Spinal n erv es • Figure 7.19
From C4
C5
C6
C7
C8
T1
Axillary
nerve
Musculocutaneous
nerve
Radial
nerve
Median
nerve
Superficial
branch of
radial nerve
Ulnar
nerve
Humerus
Radius
mlUV.
..
Median nerve —
riS~iWii
---------— Ulnar
I
nerve
Ulna
Nerves of brachial plexus
L2
1_L3
L4
/№
Femoral -
nerve
Obturator
nerve
Sciatic -
nerve
Tibial nerve -
Common -
fibular
nerve
Deep fibular -
nerve
Superficial -
fibular nerve
Tibial nerve -
Plantar -
branches
Anterior view
Posterior view
Nerves of lumbar plexus
216 CHAPTER 7
The Nervous System
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