NETTER - Neuroscience Flash Cards

Innervation of the Adrenal Gland
1. Intermediolateral cell column (lateral horn)
2. Abdominopelvic splanchnic nerves
3. Sympathetic trunk
4. Celiac, aorticorenal, and renal ganglia (collateral ganglia)
5. Postganglionic sympathetic nerve fibers to blood vessels
6. Preganglionic sympathetic fibers innervating adrenal medullary
chromaffin cells
Comment: Sympathetic input to the adrenal gland derives from
T10–L1 segments of the spinal cord and is distributed via splanchnic
nerves directly into the adrenal medulla, where preganglionic
nerve fibers form neuroeffector junctions with chromaffin cells.
These adrenal medullary chromaffin cells are neural in origin,
derived from neural crest. Sympathetic preganglionic stimulation
results in secretion of epinephrine (80%) and norepinephrine (20%)
from these chromaffin cells into the systemic circulation. These
neurotransmitters act on alpha- and beta-adrenergic receptors
on target cells, aiding in the fight-or-flight activational response,
and also may be taken up by high-affinity uptake carriers into the
postganglionic noradrenergic nerve terminals and subsequently
preferentially released and used to augment the sympathetic
activation. Endocrine input to the chromaffin cells from the
glucocorticoid-producing cells in the adrenal cortex, via an adrenal
portal vascular system, induces in chromaffin cells the expression
of phenylethanolamine N-methyl transferase (PNMT), the enzyme
that converts norepinephrine to epinephrine, thus accounting for
the predominant output of epinephrine from the chromaffin cells.
Postganglionic nerve fibers from collateral ganglia also provide
sympathetic innervation to blood vessels supplying the adrenal
gland.
Regional Neuroscience See book 9.64