Note the shape and size of the pupils in ambient bright light. This may provide helpful clues as to the cause of pupillary abnormalities, particularly where there is an underlying neurological cause. See also the separate Examination of the Eye article. There is a secondary sympathetic effect modulated by adrenergic receptors in the Edinger-Westphal nucleus which are inhibited by the direct action of sympathetic amines. The sympathetic fibres then travel with the trigeminal nerve through the superior orbital fissure to the ciliary muscle. Postsynaptic neurons travel down all the way through the brain stem on each side and finally exit through the cervical sympathetic chain, travel over the lung apices, and ascend to the superior cervical ganglia with the carotid artery, then onwards as a plexus around the internal carotid artery, passing through the cavernous sinus. The sympathetic input then comes from the hypothalamus with the first synapse at the ciliospinal centre at C8-T1 level. During sleep the pupils are partially constricted but still react to light. The pathway begins in the cortex, which exerts a modulatory effect on constriction which is lost during drowsiness and sleep but increased during intense concentration and arousal. Pupillary dilatation is controlled by the sympathetic system and is efferent only. Short ciliary nerves then innervate the iris sphincter and muscles of accommodation. They travel in the superficial part of the oculomotor nerve via the cavernous sinus and the superior orbital fissure to synapse in the ciliary ganglia. From each Edinger-Westphal nucleus, preganglionic parasympathetic fibres exit with the oculomotor nerve. ![]() Each pretectal nucleus has two pupillary motor outputs, one to the Edinger-Westphal nucleus on its own side and one to the other side. The efferent limb for pupillary constriction comes from the pretectal nucleus via the Edinger-Westphal nucleus (also in the midbrain) to the ciliary sphincter muscle of the iris. The afferent limb is made up of the retina, the optic nerve and the pretectal nucleus in the midbrain, all on the same side. read more ).The pathway for pupillary constriction for each eye has an afferent limb taking sensory information to the midbrain, and two efferent limbs (one to each eye). Symptoms and signs include diplopia, ptosis, and paresis of eye adduction and of upward and downward gaze. read more or 3rd cranial nerve palsy Third Cranial (Oculomotor) Nerve Disorders Third cranial nerve disorders can impair ocular motility, pupillary function, or both. (See also Overview of the Autonomic Nervous System.) Horner syndrome results when the cervical. read more ) and headaches or other neurologic symptoms ( Horner syndrome Horner Syndrome Horner syndrome is ptosis, miosis, and anhidrosis due to dysfunction of cervical sympathetic output. ![]() Review of systems seeks symptoms that may suggest a cause, such as birth defects or chromosomal abnormalities (congenital defects) droopy eyelid, cough, chest pain, or dyspnea (Horner syndrome) genital lesions, adenopathy, rashes, or fever ( syphilis Syphilis Syphilis is caused by the spirochete Treponema pallidum and is characterized by 3 sequential symptomatic stages separated by periods of asymptomatic latent infection. Symptoms of acute angle closure are severe ocular pain. read more, acute angle-closure glaucoma Angle-Closure Glaucoma Angle-closure glaucoma is glaucoma associated with a physically obstructed anterior chamber angle, which may be chronic or, rarely, acute. Symptoms include sudden, severe headache, usually. The most common cause of spontaneous bleeding is a ruptured aneurysm. read more, subarachnoid hemorrhage Subarachnoid Hemorrhage (SAH) Subarachnoid hemorrhage is sudden bleeding into the subarachnoid space. read more, stroke Ischemic Stroke Ischemic stroke is sudden neurologic deficits that result from focal cerebral ischemia associated with permanent brain infarction (eg, positive results on diffusion-weighted MRI). However, the retina and fluid within the anterior chamber and vitreous are often involved as well. Many disorders are accompanied by anisocoria due to iris or neurologic dysfunction but usually manifest with other, more bothersome symptoms (eg, uveitis Overview of Uveitis Uveitis is defined as inflammation of the uveal tract-the iris, ciliary body, and choroid.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |