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Ciliary Ganglion
The ciliary ganglion is a bundle of nerve 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. Structure 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasympathetic Nervous System
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. The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes considered an independent system. The autonomic nervous system is responsible for regulating the body's unconscious actions. The parasympathetic system is responsible for stimulation of "rest-and-digest" or "feed and breed" activities that occur when the body is at rest, especially after eating, including sexual arousal, salivation, lacrimation (tears), urination, digestion, and defecation. Its action is described as being complementary to that of the sympathetic nervous system, which is responsible for stimulating activities associated with the fight-or-flight response. Nerve fibres of the parasympathetic nervous system arise from the central nervous system. Specific nerves include several ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superior Cervical Ganglion
The superior cervical ganglion (SCG) is part of the autonomic nervous system (ANS); more specifically, it is part of the sympathetic nervous system, a division of the ANS most commonly associated with the fight or flight response. The ANS is composed of pathways that lead to and from ganglia, groups of nerve cells. A ganglion allows a large amount of divergence in a neuronal pathway and also enables a more localized circuitry for control of the innervated targets. The SCG is the only ganglion in the sympathetic nervous system that innervates the head and neck. It is the largest and most rostral (superior) of the three cervical ganglia. The SCG innervates many organs, glands and parts of the carotid system in the head. Structure Location The SCG is located opposite the second and third cervical vertebrae. It lies deep to the sheath of the internal carotid artery and internal jugular vein, and anterior to the Longus capitis muscle. The SCG contains neurons that supply sympathetic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasympathetic Ganglia
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. Of the head and neck These paired ganglia supply all parasympathetic innervation to the head and neck. *ciliary ganglion (sphincter pupillae, ciliary muscle) *pterygopalatine ganglion (lacrimal gland, glands of nasal cavity) *submandibular ganglion (submandibular and sublingual glands) *otic ganglion (parotid gland) Roots Each has three roots entering the ganglion and a variable number of exiting branches. * The motor root carries presynaptic parasympathetic nerve fibers ( GVE) that terminate in the ganglion and synapse with the postsynaptic fibers that, in turn, project to target organs. * The sympathetic root carries postsynaptic sympathetic fibers ( GVE) that traverse th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autonomic Ganglia Of The Head And Neck
Autonomic can refer to: *Autonomic nervous system, a division of the peripheral nervous system that supplies smooth muscle and glands, and thus influences the function of internal organs *Autonomic computing Autonomic computing (AC) is distributed computing resources with self-managing characteristics, adapting to unpredictable changes while hiding intrinsic complexity to operators and users. Initiated by IBM in 2001, this initiative ultimately aime ..., the self-managing characteristics of distributed computing resources See also * Autonomy (other) {{disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parinaud Syndrome
Parinaud's syndrome is an inability to move the eyes up and down. It is caused by compression of the vertical gaze center at the rostral interstitial nucleus of medial longitudinal fasciculus (riMLF). The eyes lose the ability to move upward and down. It is a group of abnormalities of eye movement and pupil dysfunction. It is caused by lesions of the upper brain stem and is named for Henri Parinaud (1844–1905), considered to be the father of French ophthalmology. Signs and symptoms Parinaud's syndrome is a cluster of abnormalities of eye movement and pupil dysfunction, characterized by: * Paralysis of upwards gaze: Downward gaze is usually preserved. This vertical palsy is supranuclear, so doll's head maneuver should elevate the eyes, but eventually all upward gaze mechanisms fail. * Pseudo- Argyll Robertson pupils: Accommodative paresis ensues, and pupils become mid-dilated and show light-near dissociation. * Convergence-retraction nystagmus: Attempts at upward gaze often ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argyll Robertson Pupil
Argyll Robertson pupils (AR pupils) are bilateral small pupils that reduce in size on a near object (i.e., they accommodate), but do ''not'' constrict when exposed to bright light (i.e., they do not react). They are a highly specific sign of neurosyphilis; however, Argyll Robertson pupils may also be a sign of diabetic neuropathy. In general, pupils that accommodate but do not react are said to show light-near dissociation (i.e., it is the absence of a miotic reaction to light, both direct and consensual, with the preservation of a miotic reaction to near stimulus (accommodation/convergence). AR pupils are extremely uncommon in the developed world. There is continued interest in the underlying pathophysiology, but the scarcity of cases makes ongoing research difficult. Pathophysiology The two different types of near response are caused by different underlying disease processes. ''Adie's pupil'' is caused by damage to ''peripheral'' pathways to the pupil (parasympathetic neuro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adie Syndrome
Adie syndrome, also known as Holmes-Adie syndrome, is a neurological disorder characterized by a tonically dilated pupil that reacts slowly to light but shows a more definite response to accommodation (i.e., light-near dissociation). It is frequently seen in females with absent knee or ankle jerks and impaired sweating. The syndrome is caused by damage to the postganglionic fibers of the parasympathetic innervation of the eye, usually by a viral or bacterial infection that causes inflammation, and affects the pupil of the eye and the autonomic nervous system. It is named after the British neurologists William John Adie and Gordon Morgan Holmes, who independently described the same disease in 1931. Signs and symptoms Adie syndrome presents with three hallmark symptoms, namely at least one abnormally dilated pupil (mydriasis) which does not constrict in response to light, loss of deep tendon reflexes, and abnormalities of sweating. Other signs may include hyperopia due to acc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Denervation Supersensitivity
Denervation supersensitivity/Denervation hypersensitivity is the sharp increase of sensitivity of postsynaptic membranes to a chemical transmitter after denervation Denervation is any loss of nerve supply regardless of the cause. If the nerves lost to denervation are part of the neuronal communication to a specific function in the body then altered or a loss of physiological functioning can occur. Denervation ....S. Z. Langer, "Denervation Supersensitivity", in: ''Principles of Receptor Research'' Volume 2 of the series Handbook of Psychopharmacology pp 245-280 It is a compensatory change. References {{reflist Peripheral nervous system ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accommodation (eye)
Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image or focus on an object as its distance varies. In this, distances vary for individuals from the far point—the maximum distance from the eye for which a clear image of an object can be seen, to the near point—the minimum distance for a clear image. Accommodation usually acts like a reflex, including part of the accommodation-vergence reflex, but it can also be consciously controlled. Mammals, birds and reptiles vary their eyes' optical power by changing the form of the elastic lens using the ciliary body (in humans up to 15 dioptres in the mean). Fish and amphibians vary the power by changing the distance between a rigid lens and the retina with muscles. The young human eye can change focus from distance (infinity) to as near as 6.5 cm from the eye. This dramatic change in focal power of the eye of approximately 15 dioptres (the reciprocal of focal length in metres) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Short Ciliary Nerves
The short ciliary nerves are nerves of the orbit around the eye. They are branches of the ciliary ganglion. They supply parasympathetic and sympathetic nerve fibers to the ciliary muscle, iris, and cornea. Damage to the short ciliary nerve may result in loss of the pupillary light reflex, or mydriasis. Structure The short ciliary nerves are branches of the ciliary ganglion. They arise from the forepart of the ganglion in two bundles connected with its superior and inferior angles. The lower bundle is the larger than the upper bundle. These split into between 6 and 10 filaments. They run forward with the ciliary arteries in a wavy course. One bundle is set above the optic nerve, while the other bundle is set below it. They are accompanied by the long ciliary nerves from the nasociliary. They pierce the sclera at the back part of the bulb of the eye, pass forward in delicate grooves on the inner surface of the sclera, and are distributed to the ciliary muscle, iris, and corne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edinger–Westphal Nucleus
The Edinger–Westphal nucleus (accessory oculomotor nucleus, or visceral oculomotor nucleus) is one of two nuclei of the oculomotor nerve. It is located in the midbrain. It contributes the autonomic parasympathetic (i.e. visceral) component to the oculomotor nerve, providing innervation to the iris sphincter muscle and ciliary muscle to mediate the pupillary light reflex and accommodation, respectively. It is composed of parasympathetic pre-ganglionic cell bodies that synapse in the ciliary ganglion. The term "Edinger–Westphal nucleus" also referred to what is now known as the centrally-projecting Edinger–Westphal nucleus, intermingled population of non-preganglionic neurons that do not project to the ciliary ganglion but to various regions throughout the central nervous system.. Anatomy Centrally-projecting Edinger–Westphal nucleus Alternatively, the term Edinger–Westphal nucleus is often used to refer to the adjacent population of non-preganglionic neurons that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oculomotor Nerve
The oculomotor nerve, also known as the third cranial nerve, cranial nerve III, or simply CN III, is a cranial nerve that enters the orbit through the superior orbital fissure and innervates extraocular muscles that enable most movements of the eye and that raise the eyelid. The nerve also contains fibers that innervate the intrinsic eye muscles that enable pupillary constriction and accommodation (ability to focus on near objects as in reading). The oculomotor nerve is derived from the basal plate of the embryonic midbrain. Cranial nerves IV and VI also participate in control of eye movement. Structure The oculomotor nerve originates from the third nerve nucleus at the level of the superior colliculus in the midbrain. The third nerve nucleus is located ventral to the cerebral aqueduct, on the pre-aqueductal grey matter. The fibers from the two third nerve nuclei located laterally on either side of the cerebral aqueduct then pass through the red nucleus. From the red nuc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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