Human Physiology, 14th edition (2016)

248 Chapter 9

skeletal muscles receive sympathetic but not parasympathetic

innervation.

Four of the 12 pairs of cranial nerves (chapter 8, section 8.6)

contain preganglionic parasympathetic fibers. These are the

oculomotor (III), facial (VII), glossopharyngeal (IX), and vagus

(X) nerves. Parasympathetic fibers within the first three of these

cranial nerves synapse in ganglia located in the head; fibers in

the vagus nerve synapse in terminal ganglia located in wide-

spread regions of the body. Cranial nerves IX and X contain

sensory axons as well as parasympathetic motor axons: they

fibers synapse in ganglia that are located next to—or actually
within—the organs innervated. These parasympathetic ganglia,
called terminal ganglia, supply the postganglionic fibers that
synapse with the effector cells.
The comparative structures of the sympathetic and para-
sympathetic divisions are listed in tables 9.2 and 9.3 , and
illustrated in figure 9.5. It should be noted that most parasym-
pathetic fibers do not travel within spinal nerves, as do sym-
pathetic fibers. As a result, cutaneous effectors (blood vessels,
sweat glands, and arrector pili muscles) and blood vessels in

Figure 9.4 The collateral sympathetic ganglia. These include the celiac ganglion and the superior and inferior mesenteric
ganglia. The paired adrenal glands are also shown.

Superior mesenteric

ganglion

Celiac ganglion

Inferior mesenteric

ganglion

First lumbar

sympathetic

ganglion

Adrenal gland

Pelvic sympathetic

chain

Aortic plexus

Renal plexus

Diaphragm

Parts of Body Innervated Spinal Origin of Preganglionic Fibers Origin of Postganglionic Fibers

Eye C8 and T1 Cervical ganglia

Head and neck T1 to T4 Cervical ganglia

Heart and lungs T1 to T5 Upper thoracic (paravertebral) ganglia

Upper extremities T2 to T9 Lower cervical and upper thoracic (paravertebral) ganglia

Upper abdominal viscera T4 to T9 Celiac and superior mesenteric (collateral) ganglia

Adrenal T10 and T11 Not applicable

Urinary and reproductive systems T12 to L2 Celiac and interior mesenteric (collateral) ganglia

Lower extremities T9 to L2 Lumbar and upper sacral (paravertebral) ganglia

Table 9.2 | The Sympathetic Division