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The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. [ 1 ] [ 2 ] The autonomic nervous system is responsible for regulating the body's unconscious actions.
The ciliary ganglion is a parasympathetic ganglion. Incoming parasympathetic nerve fibers form synapses with the dendrites of nerve cells within the ganglion. However, the ciliary ganglion is not simply a relay station connecting preganglionic to postganglionic nerve fibers. There are roughly twice as many incoming parasympathetic fibers as ...
Parasympathetic ganglia are the autonomic ganglia of the parasympathetic nervous system. Most are small terminal ganglia or intramural ganglia, so named because they lie near or within (respectively) the organs they innervate. The exceptions are the four paired parasympathetic ganglia of the head and neck.
The vagus nerve (/ ˈ v eɪ. ɡ ə s /), also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that carries sensory and motor fibers. It creates a pathway that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. [1]
The short ciliary nerves contain both parasympathetic and sympathetic nerve fibers. The parasympathetic fibers arise from the Edinger-Westphal nucleus and synapse in the ciliary ganglion via the oculomotor nerve, the postganglionic parasympathetics leave the ciliary ganglion in the short ciliary nerve and supply the ciliary body and iris.
Sometimes, they also supply the pupillary dilator muscle, however these axons usually travel from the nasociliary nerve to the long ciliary nerves to enter the eye. The parasympathetic root branches from the inferior division of the oculomotor nerve and carries the preganglionic parasympathetic axons from the Edinger-Westphal nucleus to the ...
The parasympathetic nerve supply comes from the parasympathetic preganglionic neurons in the sacral spinal cord and also terminates in the longitudinal and circular smooth muscle layers. Finally the somatic nerve supply arises from the urethral sphincter motor neurons in the ventral horn of the sacral spinal cord; better known as Onuf's nucleus.
Autonomic nervous system, showing splanchnic nerves in middle, and the vagus nerve as "X" in blue. The heart and organs below in list to right are regarded as viscera. The autonomic nervous system has been classically divided into the sympathetic nervous system and parasympathetic nervous system only (i.e., exclusively motor).