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(D) Riley-Day syndrome (D) Norepinephrine
(E) Raynaud's disease (E) Vasoactive intestinal polypeptide (VIP)
15. Results from increased parasympathetic 20. Is a vasodilator
16. Is a painful vasospastic disorder affecting 21. Is the neurotransmitter of the small
the digits intensely fluorescent (SIF) cells
22. Innervates apocrine sweat glands
17. Is an autosomal recessive trait character
ized by abnormal sweating and blood pres 23. Innervates eccrine (merocrine) sweat
sure instability glands
18. Results from congenital absence of gan 24. Is the transmitter responsible for penile
glion cells in the myenteric plexus erection
19. Consists of anisocoria and lack of sweat 25. Is the neurotransmitter of the arrector
ing pili muscles
Answers and Explanations
l-A. Postganglionic sympathetic cholinergic fibers innervate the eccrine (merocrine) sweat glands
and some blood vessels; blood vessels, however, are predominantly innervated by postganglionic
sympathetic adrenergic fibers. Apocrine sweat glands of the axilla are innervated by adrenergic
fibers; these glands secrete in response to mental stress.
2-B. The celiac ganglion is a sympathetic prevertebral (collateral) ganglion that contains postgan-
3-D. Destruction of the ciliary ganglion interrupts postganglionic parasympathetic fibers, which
innervate the sphincter muscle of the iris and the ciliary muscle; this results in loss of the direct
pupillary reflex, mydriasis, and paralysis of accommodation. In addition, postganglionic sympa-
thetic vasomotor fibers are interrupted, resulting in a hyperemic globe. Postganglionic sympa-
thetic pupillodilator fibers reach the iris via the nasociliary and long ciliary nerve. Severe ptosis
results from an oculomotor paralysis involving the fibers that innervate the levator palpebrae
muscle. Mild ptosis results from a lesion of the oculosympathetic fibers, which innervate the
smooth tarsal muscle (Horner's syndrome).
4-A. Contraction of the smooth muscles of the ductus deferens and seminal vesicle (ejaculation)
results from sympathetic stimulation.
286 / Neuroanatomy
5-A. Gray communicating rami are associated with all spinal nerves; they contain only non-
myelinated postganglionic sympathetic fibers. All autonomic visceromotor fibers are GVE fibers.
6-A. Visceral pain results from distension, strong contractions, mechanical stimulation of hyper-
emic organs, and ischemia with release of kinins.
7-D. Sympathectomy of the superior cervical ganglion interrupts sympathetic innervation to the
head, resulting in Horner's syndrome: mild ptosis (lid droop), miosis, facial hemianhidrosis,
vasodilation, and an apparent enophthalmos due to ptosis.
8-E. The myenteric plexus receives postganglionic sympathetic input from the prevertebral (col-
lateral) ganglia. The adrenal medulla receives preganglionic sympathetic cholinergic fibers via the
lesser splanchnic nerve.
9-A. The sacral division (S2-S4) of the autonomic nervous system (ANS) innervates the lower
abdominal and pelvic viscera, including the colon distal to the left colic flexure, the urinary blad-
der (detrusor muscle), and the genital viscera. Postganglionic parasympathetic neurons are found
in or on the viscera that they innervate.
10-E. Blood vessels receive a predominant noradrenergic innervation and a predominant sympa-
thetic input and contain cholinergic (muscarinic) receptors. Arterioles are well innervated.
Capillaries seem to have no innervation. Cerebral blood vessels respond more to circulating