Most cranial and spinal nerves contain efferent and afferent vascular fibers. The oculomotor (III), trigeminal (V), facial (VII), vagus (X), glossopharyngeal (XI), phrenic, ulnar, median, pudendal, and tibial nerves contain…
Parasympathetic Fibers. The two vagus nerves form an esophageal plexus around the lower esophagus, which is reinforced by twigs from the thoracic parts of the sympathetic trunks and from the…
The abdominal sympathetic nerves include the lumbar parts of the sympathetic trunks and their branches and contribute to the celiac, mesenteric, intermesenteric (abdominal aortic), hepatic, renal, adrenal, superior hypogastric, and…
The chief outflow of sympathetic preganglionic fibers is through the anterior roots of spinal nerves T1 to L2. The fibers pass in white rami communicantes to adjacent sympathetic trunk ganglia,…
The parasympathetic preganglionic (vagal) fibers are the axons of cells in the dorsal vagal nucleus. From the vagal cardiac nerves, they relay in ganglia of the cardiac plexus or in…
Each ganglion receives at least one white ramus communicans and contributes at least one gray ramus to the adjacent spinal nerve, although several white and gray rami communicantes may be…
Dilation of the pupil, mydriasis, occurs due to postganglionic sympathetic innervation from the superior cervical ganglion. Preganglionic fibers arise from the neurons first and second thoracic intermediolateral column and by…
SYMPATHETIC FIBERS The sympathetic preganglionic fibers for the eye arise from the intermediolateral column of the thoracic cord and travel in the ipsilateral first, second, and, occasionally, in the third…
The superior cervical ganglion is fusiform in shape. It is produced by the coalescence of the upper three or four cervical ganglia. The preganglionic fibers emerge through the uppermost thoracic…
Epinephrine (adrenaline), and the closely related norepinephrine (noradrenaline), are the chief neurotransmitters at peripheral sympathetic or adrenergic terminations, whereas acetylcholine is generally associated with parasympathetic, or cholinergic effects. However, in…
