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Head and Neck
Published in Bobby Krishnachetty, Abdul Syed, Harriet Scott, Applied Anatomy for the FRCA, 2020
Bobby Krishnachetty, Abdul Syed, Harriet Scott
Explain the pathways involved in the pupillary light reflexes.See also Chapter 7. Afferent pathway: light is sensed by the optic nerve which is transmitted via the optic tract to the pretectal nucleus of the high midbrain. This signal is then transmitted to the Edinger-Westphal nucleus (of CN III).Efferent pathway starts via parasympathetic fibres which run from the Edinger-Westphal nucleus in the oculomotor nerve (CN III), synapsing in the ciliary ganglion. From here post ganglionic short ciliary nerves leave the ciliary ganglion and innervate the iris sphincter which causes pupil constriction.
Chapter Paper 1 Answers
Published in James Day, Amy Thomson, Tamsin McAllister, Nawal Bahal, Get Through, 2014
James Day, Amy Thomson, Tamsin McAllister, Nawal Bahal
The ciliary muscle is innervated by parasympathetic fibres that are transmitted via the occulomotor nerve. They synapse within the ciliary body and the postganglionic fibres reach the eyeball in the short ciliary nerves. When the ciliary muscle contracts, it pulls the suspensory ligaments forward and slackens them. The elastic lens becomes more convex and thus the refractive power is increased.
Cranial Neuropathies II, III, IV, and VI
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Tanyatuth Padungkiatsagul, Heather E. Moss
In addition to being idiopathic, tonic pupils occur due to a variety of causes: Adie's syndrome:53Tonic pupil and absent deep tendon reflexes.Ophthalmologic findings are usually unilateral.Occurs due to aberrant reinnervation after damage to ciliary ganglion or postganglionic short ciliary nerves.Local ocular processes: injury to ciliary ganglion or short ciliary nerves: Trauma.Varicella.Syphilis.Ischemia.Strabismus surgery.Retinal photocoagulation.Autonomic dysfunction: Shy–Drager syndrome.Guillain–Barré syndrome.
Transient anisocoria after a traumatic cervical spinal cord injury: A case report
Published in The Journal of Spinal Cord Medicine, 2020
Paul Overdorf, Gary J. Farkas, Natasha Romanoski
The sympathetic innervation to the eye is from the superior cervical ganglion (Fig. 1). The superior cervical ganglion lies anterior to the transverse processes of the second and third cervical vertebra. Anterior to the ganglion lies the carotid sheath with the internal carotid artery, internal jugular vein, and vagus nerve, while the longus capitis muscle is found posterior to the ganglion. Postganglionic sympathetic fibers from the superior cervical ganglion are distributed onto the internal carotid artery and help to form the internal carotid nerve plexus, which ascends on the internal carotid artery into the carotid canal to enter the cranial cavity (Fig. 1).11 Once in the cranial cavity, postganglionic fibers from the internal carotid nerve plexus travel on the nasociliary nerve of the ophthalmic division of the trigeminal nerve, while other fibers continue from the internal carotid nerve plexus as the sympathetic root of the ciliary ganglion.12 The sympathetic root of the ciliary ganglion traverses the ciliary ganglion without synapsing (Fig. 1). These nerves then travel on the short ciliary nerves of the ciliary ganglion to the eye where they innervate the dilator pupillae muscle. Some of these postganglionic sympathetic fibers also travel on the long ciliary nerve, a nerve branch of the nasociliary nerve, to reach the eye (Fig. 1). Sympathetic activation of the dilator pupillae muscle dilates the pupil.11,12
Amplitude of Accommodation in Patients with Multiple Sclerosis
Published in Current Eye Research, 2019
Bekir Küçük, Mehmet Hamamcı, Seray Aslan Bayhan, Hasan Ali Bayhan, Levent Ertuğrul Inan
When the target distance is changed, the lens power must be altered to clearly view it; this is known as ocular accommodation.25 The accommodation reflex starts in the retinal ganglion cells with the light reflex. These impulses are sent through the optic nerve, the optic chiasma, and the optic tract. Most optic tract fibers go to the pretectal area, although some fibers synapse with the second-order neurons in the lateral geniculate nucleus of the thalamus. Then, second-order neurons carry the impulses through the optic radiation to the visual cortex. Impulses pass from the visual cortex to the prefrontal cortex, and fibers pass through the internal capsule to reach the midbrain. Then, the fibers in the midbrain synapse with the oculomotor nucleus and the Edinger-Westphal nucleus.26 The motor fibers are carried by the oculomotor nerve from the oculomotor nucleus to the medial rectus muscle, where both eyes converge. The efferent fibers of the Edinger-Westphal nucleus (which is the parasympathetic autonomic nucleus) accompany the oculomotor nerve and synapse in the ciliary ganglion. Then, the postganglionic fibers of the ciliary ganglion pass the short ciliary nerves to supply the sphincter pupillae muscle and the ciliary muscle, which allows the lens to thicken27 (Figure 1). This mechanism is controlled by the autonomic nervous system.23
Tonic Pupil in Cytomegalovirus Anterior Uveitis in an Immunocompetent Adult Male – A Case Report
Published in Ocular Immunology and Inflammation, 2018
Kalpana Babu, Deepika C. Parameswarappa, Bhagya Sudheer
Involvement of the ciliary ganglion, short ciliary nerves in the orbital, intraocular or suprachoroidal spaces can cause tonic pupil. Tonic pupils are generally divided into local, neuropathic, and Adie syndrome.2 The local tonic pupil is typically unilateral and is due to orbital or systemic lesions that affect the ciliary ganglion or short ciliary nerves in isolation. It is seen in herpes zoster, chicken pox, measles, diphtheria, syphilis, Lyme disease, sarcoidosis, influenza, sinusitis, Vogt-Koyanagi-Harada disease (VKH), rheumatoid arthritis, giant cell arthritis, viral hepatitis, choroiditis, metastatic choroidal and orbital tumors, blunt and penetrating orbital injury, postintraocular and orbital surgeries, laser photocoagulation, and intraocular siderosis. Occurrence of tonic pupil has never been reported in CMV-related anterior uveitis3 (Medline search). The supersensitivity to pilocarpine 0.125% in our case confirmed the diagnosis. In our case, the neurological examination including deep tendon reflexes was normal.