Which Statement About the Sympathetic Nervous System is FALSE?
Statement D is FALSE: The inferior hypogastric plexus does NOT lie in front of the promontory of the sacrum between the two common iliac arteries—this describes the superior hypogastric plexus (presacral nerve), not the inferior hypogastric plexus.
Analysis of Each Statement
Statement A: Stellate Ganglionectomy for Long QT Syndrome - TRUE
- Left cardiac sympathetic denervation (stellate ganglionectomy) is an established treatment for long QT syndrome, particularly in high-risk patients with recurrent syncope or cardiac arrest despite beta-blocker therapy 1.
- The European Society of Cardiology guidelines specifically state that "left stellate ganglionectomy or ICDs should be considered" when patients continue to experience symptoms despite beta-blockade 1.
- The ACC/AHA/HRS guidelines confirm that left cardiac sympathetic denervation reduces the number of appropriate ICD shocks and ventricular arrhythmia burden in long QT syndrome patients 1.
- This procedure is particularly effective in long QT syndrome type 1 and type 3 1.
- The mechanism involves interrupting the sympathetic trigger for life-threatening arrhythmias, as "the trigger for most episodes of life-threatening arrhythmias is a sudden increase in sympathetic activity, mediated by left-sided cardiac sympathetic nerves" 1.
Statement B: Anhydrosis with Ganglionectomy - TRUE
- Sympathetic ganglionectomy consistently produces anhydrosis (absence of sweating) in the distribution of the interrupted sympathetic fibers 2.
- This is the intended therapeutic effect when sympathectomy is performed for hyperhidrosis 2, 3.
- The sympathetic nervous system provides the primary innervation to sweat glands, so interruption of this pathway eliminates sweating in the affected region 2.
Statement C: Intercostal Nerve Connections - TRUE
- Each intercostal nerve is connected to the sympathetic trunk by white and gray rami communicantes, though the exact number varies 4, 3, 5.
- White rami communicantes carry preganglionic sympathetic fibers from the spinal cord to the sympathetic chain 4, 6.
- Gray rami communicantes carry postganglionic sympathetic fibers from the sympathetic ganglia to the spinal nerves 4, 2.
- Research confirms that "all sensory and sympathetic neurones were located ipsilaterally" and demonstrates the consistent presence of these connections in thoracic segments 4.
- Anatomical studies show that gray rami "consistently lie between the intercostal nerve and the homonymous sympathetic ganglion" 2.
Statement D: Inferior Hypogastric Plexus Location - FALSE
- This statement incorrectly describes the location of the inferior hypogastric plexus.
- The anatomical description given—"lies in front of the promontory of the sacrum between the two common iliac arteries"—actually describes the superior hypogastric plexus, which is also called the presacral nerve.
- The inferior hypogastric plexus is located more inferiorly in the pelvis, lateral to the rectum and other pelvic organs, not at the sacral promontory between the common iliac arteries.
Statement E: Acetylcholine and Sweat Glands - TRUE
- Sympathetic innervation to sweat glands is unique in that it uses acetylcholine as the neurotransmitter, despite being part of the sympathetic nervous system 7.
- This is an exception to the general rule that sympathetic postganglionic neurons use norepinephrine.
- The statement correctly identifies this unusual cholinergic sympathetic pathway to sweat glands.
Clinical Pitfall
The key anatomical distinction is that the superior hypogastric plexus (presacral nerve) lies anterior to the sacral promontory between the common iliac bifurcations, while the inferior hypogastric plexus is located more inferiorly and laterally in the pelvis. Confusing these two structures can lead to surgical complications during pelvic procedures.