Innervation of Stomach and Proximal Duodenum
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…
Carotid Body and Carotid Sinus
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…
Innervation of Blood Vessels
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,…
Innervation of Heart
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…
Thoracic Sympathetic Chain and Splanchnic Nerves
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…
Ciliary Ganglion
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…
Autonomic Distribution to the Head and the Neck
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…
Autonomic Nerves in Neck
The cervicothoracic (stellate) ganglion is formed by the fusion of the seventh and eighth cervical ganglia with the first and/or second thoracic ganglia. It is an irregularly fusiform structure with…
Autonomic Nerves in Head
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…
Cholinergic and Adrenergic Nerves
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…
