The submandibular ganglion is small and fusiform in shape. It is situated above the deep portion of the submandibular gland , on the hyoglossus muscle , near the posterior border of the mylohyoid muscle. The ganglion 'hangs' by two nerve filaments from the lower border of the lingual nerve itself a branch of the mandibular nerve , CN V 3.
It is suspended from the lingual nerve by two filaments, one anterior and one posterior. Through the posterior of these it receives a branch from the chorda tympani nerve which runs in the sheath of the lingual nerve. Like other parasympathetic ganglia of the head and neck, the submandibular ganglion is the site of synapse for parasympathetic fibers and carries other types of nerve fiber that do not synapse in the ganglion. In summary, the fibers carried in the ganglion are:.
Template:Trigeminal nerve Template:Autonomic. Template:WikiDoc Sources. Mandibular division of trifacial nerve, seen from the middle line. The parasympathetic fibers originate from the upper part of the midbrain in an area called the superior colliculus. The collection of cell bodies in the central nervous system where they originate is called the Edinger-Westphal nucleus. They travel along the third cranial nerve. The nerve fibers enter the orbit of the eye through the superior orbital fissure.
These preganglionic before reaching the ganglion fibers synapse with postganglionic fibers in the ciliary ganglion. The postganglionic fibers then enter the eyeball. Sensory nerve fibers originate from the nasociliary nerve, which comes from the ophthalmic branch of the trigeminal nerve , and enter the eye through the superior orbital fissure. The sympathetic root fibers travel with the internal carotid artery and enter the orbit through the superior orbital fissure.
These sympathetic fibers, like the sensory fibers, pass through the ciliary ganglion uninterrupted. The ciliary ganglia are located behind each eye in the posterior part of the eye orbit, and are embedded in the fat surrounding the eyeball. The ganglia are about 2 mm horizontally and 1 mm vertically, and contain approximately 2, nerve cell bodies.
The ciliary ganglia receive their blood supply from the posterior lateral ciliary artery and the lateral muscular arterial trunk. Relative to other structures around the eye, the ciliary ganglion is:. The ciliary ganglion may vary in position with respect to the surrounding structures, and it may vary in size from 1. It may also vary in distance from reference landmarks such as the optic nerve.
Additionally, the size of the bunches of nerve fibers entering and leaving the ciliary body may vary. This variation is important for surgeons to recognize. The pupil of the eye participates in two reflexes that are controlled by the ciliary muscle:. The parasympathetic nerve fibers that synapse in the ciliary ganglion travel to the circular pupillary muscles and the ciliary body. The circular papillary muscles surround the pupil, the opening in the center of the iris of the eye.
When nerve fibers stimulate these muscles to contract, the pupil becomes smaller. A decrease in pupil size is a natural response to bright light.
Contracting the pupil filters out light rays coming in at an angle. When there is plenty of light, these light rays bounce around inside the eye, making the visual image blurry.
Parasympathetic fibers from the ciliary ganglia also go to the ciliary muscles. The lens of the eye bends light to focus it, much like the lens of a camera bends light to focus the image on the film. When your eye is looking at a close object, nerve impulses from nerves in the ciliary ganglia stimulate the ciliary muscles to contract. This process bends light rays more and focuses the image on the retina of the eye. Sensory nerve fibers pass through the ciliary ganglion without synapsing to carry sensations from the cornea , iris , and ciliary body to the brain.
Sympathetic nerve fibers also pass through the ciliary ganglion without synapsing. They originate from the superior cervical ganglion, near the angle of the jaw. They innervate the muscles that dilate the pupil make the pupil bigger. If you have this condition, your pupil will not exhibit the expected response to bright light, rapid constriction to filter out excess light. It is theorized that the ciliary body is suddenly denervated and then slowly reinnervated.
The sudden denervation of the ciliary ganglion results in a dilated pupil that will not respond to light and a loss of accommodation due to the inability of the lens to become more convex. Regeneration of the nerves in the ciliary body happens over one to two years.
Adie syndrome, or Holmes-Adie syndrome, is a rare disorder in which both tonic pupil and absent or poor tendon reflexes are found. The cause is unknown, but it may be due to trauma, surgery, lack of blood flow, or infection. Tendon reflexes are elicited when your healthcare provider taps on a tendon, such as the one below your knee, with a rubber hammer. Adie syndrome is more common in females than in males. The disorder is most commonly diagnosed in adults between the ages of 25 and Ross syndrome is a variant of Adie syndrome that affects the ability to sweat as well.
If you have Ross syndrome in addition to a tonic pupil and decreased tendon reflexes, you may notice that some parts of your body sweat excessively while others are unable to sweat properly. The inability to sweat can lead to heat intolerance. The ciliary ganglion can also be injured directly or as a result of surgery. Surgical procedures to repair orbital fractures or remove tumors inside the bony eye orbit can damage the ciliary ganglion.
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Adie syndrome. Updated Ophthalmology Review. Ciliary ganglion. Updated April 25, Anatomical study of the roots of cranial parasympathetic ganglia: a contribution to medical education. Ann Anat. Kardon R. Chapter Anatomy and physiology of the autonomic nervous system. Walsh and Hoyt's clinical neuro-ophthalmology, 6th ed. Anatomical variations of the ciliary ganglion with an emphasis on the location in the orbit.
Anat Sci Int. Tandon R. Chapter 4: The neurology of vision. In: Sihota R, Tandon R, eds. Elsevier Health Sciences; Overview of the anatomy, physiology, and pharmacology of the autonomic nervous system.
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