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…
NEUROLOGY
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 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…
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 Reflex Pathways
The autonomic reflex arc is similar to the somatic reflex arc, although, in the somatic arcs, the interneurons and their connections are entirely within the central nervous system (CNS). In…
Leprosy and Other Infections Sometimes Causing Peripheral Neuropathies
LYME Lyme disease in the United States is caused by Borrelia burgdorferi infection transmitted by the Ixodes tick. In the majority of infected individuals, Lyme disease manifests first with erythema…
General Topography of Autonomic Nervous System
The central autonomic components include regions of the cerebral cortex, diencephalon, and brainstem. In the cerebral cortex, autonomic areas include the frontal premotor areas, telencephalic cortex in the hippocampus, insular…
