Abducens Nerve: The 6th cranial nerve which originates in the ABDUCENS NUCLEUS of the PONS and sends motor fibers to the lateral rectus muscles of the EYE. Damage to the nerve or its nucleus disrupts horizontal eye movement control.Abducens Nerve Diseases: Diseases of the sixth cranial (abducens) nerve or its nucleus in the pons. The nerve may be injured along its course in the pons, intracranially as it travels along the base of the brain, in the cavernous sinus, or at the level of superior orbital fissure or orbit. Dysfunction of the nerve causes lateral rectus muscle weakness, resulting in horizontal diplopia that is maximal when the affected eye is abducted and ESOTROPIA. Common conditions associated with nerve injury include INTRACRANIAL HYPERTENSION; CRANIOCEREBRAL TRAUMA; ISCHEMIA; and INFRATENTORIAL NEOPLASMS.Abducens Nerve Injury: Traumatic injury to the abducens, or sixth, cranial nerve. Injury to this nerve results in lateral rectus muscle weakness or paralysis. The nerve may be damaged by closed or penetrating CRANIOCEREBRAL TRAUMA or by facial trauma involving the orbit.Horner Syndrome: A syndrome associated with defective sympathetic innervation to one side of the face, including the eye. Clinical features include MIOSIS; mild BLEPHAROPTOSIS; and hemifacial ANHIDROSIS (decreased sweating)(see HYPOHIDROSIS). Lesions of the BRAIN STEM; cervical SPINAL CORD; first thoracic nerve root; apex of the LUNG; CAROTID ARTERY; CAVERNOUS SINUS; and apex of the ORBIT may cause this condition. (From Miller et al., Clinical Neuro-Ophthalmology, 4th ed, pp500-11)Cavernous Sinus: An irregularly shaped venous space in the dura mater at either side of the sphenoid bone.Diplopia: A visual symptom in which a single object is perceived by the visual cortex as two objects rather than one. Disorders associated with this condition include REFRACTIVE ERRORS; STRABISMUS; OCULOMOTOR NERVE DISEASES; TROCHLEAR NERVE DISEASES; ABDUCENS NERVE DISEASES; and diseases of the BRAIN STEM and OCCIPITAL LOBE.Petrous Bone: The dense rock-like part of temporal bone that contains the INNER EAR. Petrous bone is located at the base of the skull. Sometimes it is combined with the MASTOID PROCESS and called petromastoid part of temporal bone.Trochlear Nerve: The 4th cranial nerve. The trochlear nerve carries the motor innervation of the superior oblique muscles of the eye.Cranial Nerve Diseases: Disorders of one or more of the twelve cranial nerves. With the exception of the optic and olfactory nerves, this includes disorders of the brain stem nuclei from which the cranial nerves originate or terminate.Eye Pain: A dull or sharp painful sensation associated with the outer or inner structures of the eyeball, having different causes.Ophthalmoplegia: Paralysis of one or more of the ocular muscles due to disorders of the eye muscles, neuromuscular junction, supporting soft tissue, tendons, or innervation to the muscles.Oculomotor Nerve: The 3d cranial nerve. The oculomotor nerve sends motor fibers to the levator muscles of the eyelid and to the superior rectus, inferior rectus, and inferior oblique muscles of the eye. It also sends parasympathetic efferents (via the ciliary ganglion) to the muscles controlling pupillary constriction and accommodation. The motor fibers originate in the oculomotor nuclei of the midbrain.Oculomotor Muscles: The muscles that move the eye. Included in this group are the medial rectus, lateral rectus, superior rectus, inferior rectus, inferior oblique, superior oblique, musculus orbitalis, and levator palpebrae superioris.Cranial Nerve Neoplasms: Benign and malignant neoplasms that arise from one or more of the twelve cranial nerves.Skull Fracture, Basilar: Fractures which extend through the base of the SKULL, usually involving the PETROUS BONE. Battle's sign (characterized by skin discoloration due to extravasation of blood into the subcutaneous tissue behind the ear and over the mastoid process), CRANIAL NEUROPATHIES, TRAUMATIC; CAROTID-CAVERNOUS SINUS FISTULA; and CEREBROSPINAL FLUID OTORRHEA are relatively frequent sequelae of this condition. (Adams et al., Principles of Neurology, 6th ed, p876)Oculomotor Nerve Diseases: Diseases of the oculomotor nerve or nucleus that result in weakness or paralysis of the superior rectus, inferior rectus, medial rectus, inferior oblique, or levator palpebrae muscles, or impaired parasympathetic innervation to the pupil. With a complete oculomotor palsy, the eyelid will be paralyzed, the eye will be in an abducted and inferior position, and the pupil will be markedly dilated. Commonly associated conditions include neoplasms, CRANIOCEREBRAL TRAUMA, ischemia (especially in association with DIABETES MELLITUS), and aneurysmal compression. (From Adams et al., Principles of Neurology, 6th ed, p270)Trigeminal Nerve: The 5th and largest cranial nerve. The trigeminal nerve is a mixed motor and sensory nerve. The larger sensory part forms the ophthalmic, mandibular, and maxillary nerves which carry afferents sensitive to external or internal stimuli from the skin, muscles, and joints of the face and mouth and from the teeth. Most of these fibers originate from cells of the TRIGEMINAL GANGLION and project to the TRIGEMINAL NUCLEUS of the brain stem. The smaller motor part arises from the brain stem trigeminal motor nucleus and innervates the muscles of mastication.Paralysis: A general term most often used to describe severe or complete loss of muscle strength due to motor system disease from the level of the cerebral cortex to the muscle fiber. This term may also occasionally refer to a loss of sensory function. (From Adams et al., Principles of Neurology, 6th ed, p45)Duane Retraction Syndrome: A syndrome characterized by marked limitation of abduction of the eye, variable limitation of adduction and retraction of the globe, and narrowing of the palpebral fissure on attempted adduction. The condition is caused by aberrant innervation of the lateral rectus by fibers of the OCULOMOTOR NERVE.Mucocele: A retention cyst of the salivary gland, lacrimal sac, paranasal sinuses, appendix, or gallbladder. (Stedman, 26th ed)Eye Movements: Voluntary or reflex-controlled movements of the eye.Electronystagmography: Recording of nystagmus based on changes in the electrical field surrounding the eye produced by the difference in potential between the cornea and the retina.Nerve Compression Syndromes: Mechanical compression of nerves or nerve roots from internal or external causes. These may result in a conduction block to nerve impulses (due to MYELIN SHEATH dysfunction) or axonal loss. The nerve and nerve sheath injuries may be caused by ISCHEMIA; INFLAMMATION; or a direct mechanical effect.Dura Mater: The outermost of the three MENINGES, a fibrous membrane of connective tissue that covers the brain and the spinal cord.Cranial Fossa, Posterior: The infratentorial compartment that contains the CEREBELLUM and BRAIN STEM. It is formed by the posterior third of the superior surface of the body of the sphenoid (SPHENOID BONE), by the occipital, the petrous, and mastoid portions of the TEMPORAL BONE, and the posterior inferior angle of the PARIETAL BONE.Skull Base: The inferior region of the skull consisting of an internal (cerebral), and an external (basilar) surface.TurtlesSciatic Nerve: A nerve which originates in the lumbar and sacral spinal cord (L4 to S3) and supplies motor and sensory innervation to the lower extremity. The sciatic nerve, which is the main continuation of the sacral plexus, is the largest nerve in the body. It has two major branches, the TIBIAL NERVE and the PERONEAL NERVE.Neurilemmoma: A neoplasm that arises from SCHWANN CELLS of the cranial, peripheral, and autonomic nerves. Clinically, these tumors may present as a cranial neuropathy, abdominal or soft tissue mass, intracranial lesion, or with spinal cord compression. Histologically, these tumors are encapsulated, highly vascular, and composed of a homogenous pattern of biphasic fusiform-shaped cells that may have a palisaded appearance. (From DeVita Jr et al., Cancer: Principles and Practice of Oncology, 5th ed, pp964-5)Peripheral Nerves: The nerves outside of the brain and spinal cord, including the autonomic, cranial, and spinal nerves. Peripheral nerves contain non-neuronal cells and connective tissue as well as axons. The connective tissue layers include, from the outside to the inside, the epineurium, the perineurium, and the endoneurium.Paresis: A general term referring to a mild to moderate degree of muscular weakness, occasionally used as a synonym for PARALYSIS (severe or complete loss of motor function). In the older literature, paresis often referred specifically to paretic neurosyphilis (see NEUROSYPHILIS). "General paresis" and "general paralysis" may still carry that connotation. Bilateral lower extremity paresis is referred to as PARAPARESIS.Cranial Nerves: Twelve pairs of nerves that carry general afferent, visceral afferent, special afferent, somatic efferent, and autonomic efferent fibers.Brain Stem: The part of the brain that connects the CEREBRAL HEMISPHERES with the SPINAL CORD. It consists of the MESENCEPHALON; PONS; and MEDULLA OBLONGATA.Optic Nerve: The 2nd cranial nerve which conveys visual information from the RETINA to the brain. The nerve carries the axons of the RETINAL GANGLION CELLS which sort at the OPTIC CHIASM and continue via the OPTIC TRACTS to the brain. The largest projection is to the lateral geniculate nuclei; other targets include the SUPERIOR COLLICULI and the SUPRACHIASMATIC NUCLEI. Though known as the second cranial nerve, it is considered part of the CENTRAL NERVOUS SYSTEM.Meningioma: A relatively common neoplasm of the CENTRAL NERVOUS SYSTEM that arises from arachnoidal cells. The majority are well differentiated vascular tumors which grow slowly and have a low potential to be invasive, although malignant subtypes occur. Meningiomas have a predilection to arise from the parasagittal region, cerebral convexity, sphenoidal ridge, olfactory groove, and SPINAL CANAL. (From DeVita et al., Cancer: Principles and Practice of Oncology, 5th ed, pp2056-7)Nerve Fibers: Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM.Magnetic Resonance Imaging: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.Optic Nerve Diseases: Conditions which produce injury or dysfunction of the second cranial or optic nerve, which is generally considered a component of the central nervous system. Damage to optic nerve fibers may occur at or near their origin in the retina, at the optic disk, or in the nerve, optic chiasm, optic tract, or lateral geniculate nuclei. Clinical manifestations may include decreased visual acuity and contrast sensitivity, impaired color vision, and an afferent pupillary defect.Olfactory Nerve Diseases: Diseases of the first cranial (olfactory) nerve, which usually feature anosmia or other alterations in the sense of smell and taste. Anosmia may be associated with NEOPLASMS; CENTRAL NERVOUS SYSTEM INFECTIONS; CRANIOCEREBRAL TRAUMA; inherited conditions; toxins; METABOLIC DISEASES; tobacco abuse; and other conditions. (Adams et al., Principles of Neurology, 6th ed, pp229-31)Peripheral Nerve Injuries: Injuries to the PERIPHERAL NERVES.Dictionaries, MedicalExotropia: A form of ocular misalignment where the visual axes diverge inappropriately. For example, medial rectus muscle weakness may produce this condition as the affected eye will deviate laterally upon attempted forward gaze. An exotropia occurs due to the relatively unopposed force exerted on the eye by the lateral rectus muscle, which pulls the eye in an outward direction.Cellular Phone: Analog or digital communications device in which the user has a wireless connection from a telephone to a nearby transmitter. It is termed cellular because the service area is divided into multiple "cells." As the user moves from one cell area to another, the call is transferred to the local transmitter.Sphenoid Sinusitis: Inflammation of the NASAL MUCOSA in the SPHENOID SINUS. Isolated sphenoid sinusitis is uncommon. It usually occurs in conjunction with other paranasal sinusitis.Encyclopedias as Topic: Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)Urinary Fistula: An abnormal passage in any part of the URINARY TRACT between itself or with other organs.Ossification of Posterior Longitudinal Ligament: A calcification of the posterior longitudinal ligament of the spinal column, usually at the level of the cervical spine. It is often associated with anterior ankylosing hyperostosis.Longitudinal Ligaments: Two extensive fibrous bands running the length of the vertebral column. The anterior longitudinal ligament (ligamentum longitudinale anterius; lacertus medius) interconnects the anterior surfaces of the vertebral bodies; the posterior longitudinal ligament (ligamentum longitudinale posterius) interconnects the posterior surfaces. The commonest clinical consideration is OSSIFICATION OF POSTERIOR LONGITUDINAL LIGAMENT. (From Stedman, 25th ed)Chest Tubes: Plastic tubes used for drainage of air or fluid from the pleural space. Their surgical insertion is called tube thoracostomy.Chiropractic: An occupational discipline founded by D.D. Palmer in the 1890's based on the relationship of the spine to health and disease.Manipulation, Chiropractic: Procedures used by chiropractors to treat neuromusculoskeletal complaints.Manipulation, Spinal: Adjustment and manipulation of the vertebral column.Medicare Part B: The voluntary portion of Medicare, known as the Supplementary Medical Insurance (SMI) Program, that includes physician's services, home health care, medical services, outpatient hospital services, and laboratory, pathology, and radiology services. All persons entitled to Medicare Part A may enroll in Medicare Part B on a monthly premium basis.Complementary Therapies: Therapeutic practices which are not currently considered an integral part of conventional allopathic medical practice. They may lack biomedical explanations but as they become better researched some (PHYSICAL THERAPY MODALITIES; DIET; ACUPUNCTURE) become widely accepted whereas others (humors, radium therapy) quietly fade away, yet are important historical footnotes. Therapies are termed as Complementary when used in addition to conventional treatments and as Alternative when used instead of conventional treatment.Inflation, Economic: An increase in the volume of money and credit relative to available goods resulting in a substantial and continuing rise in the general price level.Small-Area Analysis: A method of analyzing the variation in utilization of health care in small geographic or demographic areas. It often studies, for example, the usage rates for a given service or procedure in several small areas, documenting the variation among the areas. By comparing high- and low-use areas, the analysis attempts to determine whether there is a pattern to such use and to identify variables that are associated with and contribute to the variation.