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The distal large bowel from the point of neuronal arrest to the anus is continuously aganglionic. It is a rare disorder (1:5000), with prevalence among males being four times that of females. [10] Achalasia is a motor disorder of the esophagus characterized by decrease in ganglion cell density in the myenteric plexus. The cause of the lesion is ...
Another major difference between the two ANS (autonomic nervous systems) is divergence. Whereas in the parasympathetic division there is a divergence factor of roughly 1:4, in the sympathetic division there can be a divergence of up to 1:20. This is due to the number of synapses formed by the preganglionic fibers with ganglionic neurons.
The term "ganglion" refers to the peripheral nervous system. [ 1 ] However, in the brain (part of the central nervous system ), the basal ganglia are a group of nuclei interconnected with the cerebral cortex , thalamus , and brainstem , associated with a variety of functions: motor control, cognition, emotions, and learning.
Although an autonomic ganglion is the site where preganglionic fibers synapse on postganglionic neurons, the presence of small interneurons has been recognized. These cells exhibit catecholamine fluorescence and are referred to as small intensely fluorescent (SIF) cells.
There are usually 22–23 pairs of these ganglia: three cervical ganglia, 12 thoracic ganglia (the stellate ganglion (cervicothoracic) is formed from the fusion of the first thoracic ganglion with the inferior cervical ganglion), four lumbar ganglia, and four or five sacral ganglia. In the area of the coccyx there is a small ganglion impar. The ...
In the middle cranial fossa, the nerve is situated between the two layers of the dura mater [1]: 450, 498 and passes obliquely anterior-ward [1]: 450 along a groove upon the floor of the fossa [1]: 509 - the groove for the greater petrosal nerve - that is situated upon the anterosuperior aspect of the petrous part of the temporal bone [3]: 842 ...
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The lesser petrosal nerve (also known as the small superficial petrosal nerve) is the general visceral efferent (GVE) nerve conveying pre-ganglionic parasympathetic secretomotor fibers for the parotid gland from the tympanic plexus to the otic ganglion (where they synapse). It passes out of the tympanic cavity through the petrous part of the ...