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Ciliary ganglion
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Ciliary ganglion
The ciliary ganglion is a parasympathetic ganglion located just behind the eye in the posterior orbit. It is 1–2 mm in diameter and in humans contains approximately 2,500 neurons. The ganglion contains postganglionic parasympathetic neurons. These neurons supply the pupillary sphincter muscle, which constricts the pupil, and the ciliary muscle which contracts to make the lens more convex. Both of these muscles are involuntary since they are controlled by the parasympathetic division of the autonomic nervous system.
The ciliary ganglion is one of four parasympathetic ganglia of the head. The others are the submandibular ganglion, pterygopalatine ganglion, and otic ganglion.
The ciliary ganglion contains postganglionic parasympathetic neurons that supply the ciliary muscle and the pupillary sphincter muscle. Because of the much larger size of the ciliary muscle, 95% of the neurons in the ciliary ganglion innervate it compared to the pupillary sphincter.
Three types of axons enter the ciliary ganglion but only the preganglionic parasympathetic axons synapse there. The entering axons are arranged into three roots which join enter the posterior surface of the ganglion:
Exiting from the anterior surface of the ciliary ganglion are the short ciliary nerves which contain the sensory, postganglionic sympathetic and postganglionic parasympathetic axons to the eye.
Diseases of the ciliary ganglion produce a "tonic pupil", which is a pupil that does not react to light (it is “fixed”) and has an abnormally slow and prolonged response to attempted near vision (accommodation).
When a person with an Adie pupil attempts to focus on a nearby object, the pupil (which would normally constrict rapidly) constricts slowly. On close inspection, the constricted pupil is not perfectly round. When the person focuses on a more distant object (say the far side of the room), the pupil (which would normally dilate immediately) remains constricted for several minutes, and then slowly dilates back to the expected size.
Tonic pupils are fairly common – they are seen in roughly 1 out of every 500 people. A person with anisocoria (one pupil bigger than the other) whose pupil does not react to light (does not constrict when exposed to bright light) most likely has Adie syndrome – idiopathic degeneration of the ciliary ganglion.
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Ciliary ganglion
The ciliary ganglion is a parasympathetic ganglion located just behind the eye in the posterior orbit. It is 1–2 mm in diameter and in humans contains approximately 2,500 neurons. The ganglion contains postganglionic parasympathetic neurons. These neurons supply the pupillary sphincter muscle, which constricts the pupil, and the ciliary muscle which contracts to make the lens more convex. Both of these muscles are involuntary since they are controlled by the parasympathetic division of the autonomic nervous system.
The ciliary ganglion is one of four parasympathetic ganglia of the head. The others are the submandibular ganglion, pterygopalatine ganglion, and otic ganglion.
The ciliary ganglion contains postganglionic parasympathetic neurons that supply the ciliary muscle and the pupillary sphincter muscle. Because of the much larger size of the ciliary muscle, 95% of the neurons in the ciliary ganglion innervate it compared to the pupillary sphincter.
Three types of axons enter the ciliary ganglion but only the preganglionic parasympathetic axons synapse there. The entering axons are arranged into three roots which join enter the posterior surface of the ganglion:
Exiting from the anterior surface of the ciliary ganglion are the short ciliary nerves which contain the sensory, postganglionic sympathetic and postganglionic parasympathetic axons to the eye.
Diseases of the ciliary ganglion produce a "tonic pupil", which is a pupil that does not react to light (it is “fixed”) and has an abnormally slow and prolonged response to attempted near vision (accommodation).
When a person with an Adie pupil attempts to focus on a nearby object, the pupil (which would normally constrict rapidly) constricts slowly. On close inspection, the constricted pupil is not perfectly round. When the person focuses on a more distant object (say the far side of the room), the pupil (which would normally dilate immediately) remains constricted for several minutes, and then slowly dilates back to the expected size.
Tonic pupils are fairly common – they are seen in roughly 1 out of every 500 people. A person with anisocoria (one pupil bigger than the other) whose pupil does not react to light (does not constrict when exposed to bright light) most likely has Adie syndrome – idiopathic degeneration of the ciliary ganglion.
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