| lens, compound | <microscopy> A lens composed of two or more separate pieces of glass or other optical maternal. These component pieces or elements may or may not be cemented together. A common form of compound lens is a two-element objective, one element being a converging lens of crown glass and the other a diverging lens of flint glass. The combination of suitable glasses or other optical materials (plastics, minerals) properly ground and polished reduces aberrations normally present in a single lens. (05 Aug 1998) |
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| abducens nerve | <anatomy, nerve> The 6th cranial nerve. The abducens nerve originates in the abducens nucleus of the pons and sends motor fibres to the lateral rectus muscles of the eye. Damage to the nerve or its nucleus disrupts horizontal eye movement control. (12 Dec 1998) |
| abducent nerve | <anatomy> The abducent nerve enervates a muscle which moves the eyeball. Lesions of the sixth cranial nerve result in deviation of the eyeball outward and double vision. Synonym: cranial nerve VI. (27 Sep 1997) |
| accessory nerve | <anatomy, nerve> The accessory nerve enervates the sternocleidomastoid muscles and the trapezius muscles. Lesions of the eleventh result in drooping of the shoulder and inability to rotate the head away from the affected side. Synonym: cranial nerve XI. (27 Sep 1997) |
| accessory nerve lymph nodes | The nodes of the lateral deep cervical group that are located along the accessory nerve; their efferent vessels pass to the supraclavicular lymph nodes. Synonym: companion lymph nodes of accessory nerve, nodi lymphatici comitantes nervi accessorii. (05 Mar 2000) |
| accessory nerve trunk | Part of the accessory nerve formed within the cranial cavity by the union of the cranial and spinal roots, which then divides within the jugular foramen into internal and external branches, the former uniting with the vagus, the latter exiting the foramen as in independent branch which is commonly considered to be the accessory nerve. (05 Mar 2000) |
| accessory portion of spinal accessory nerve | <anatomy, nerve> The roots of the accessory nerve which arise from the medulla; the nerve fibres of the cranial root join the intracranial portion of the vagus nerve and are distributed to the pharyngeal plexus, providing the motor innervation of the soft palate (except the tensor veli palati) and the pharynx. Synonym: pars vagalis nervi accessorii, radices craniales, accessory portion of spinal accessory nerve, cranial roots, vagal part of accessory nerve, vagal part. (05 Mar 2000) |
| accommodation of nerve | <anatomy, nerve> The property of a nerve by which it adjusts to a slowly increasing strength of stimulus, so that its threshold of excitation is greater than it would be were the stimulus strength to have risen more rapidly. (05 Mar 2000) |
| accompanying vein of hypoglossal nerve | Runs with the hypoglossal nerve below and lateral to the hyoglossus muscle, emptying usually into the lingual vein. Synonym: accompanying vein of hypoglossal nerve. (05 Mar 2000) |
| acoustic nerve | <anatomy, nerve> The 8th cranial nerve. The acoustic (or vestibulocochlear) nerve has a cochlear part which is concerned with hearing and a vestibular part which mediates the sense of balance and head position. The fibres of the cochlear nerve originate from neurons of the spiral ganglion and project to the cochlear nuclei. The fibres of the vestibular nerve arise from neurons of scarpa's ganglion and project to the vestibular nuclei. (12 Dec 1998) |
| acoustic nerve diseases | Diseases of the eighth cranial nerve. These include vestibular neuronitis, cochlear neuritis and acoustic neuroma. (12 Dec 1998) |
| afferent nerve | <anatomy, physiology> A nerve which transmits impulses from the tissues to the brain and spinal cord (for example sensory nerve). (27 Sep 1997) |
| Andersch's nerve | <anatomy, nerve> A nerve from the inferior ganglion of the glossopharyngeal nerve, passing through the tympanic canaliculus to the tympanic cavity, forming there the tympanic plexus which supplies the mucous membrane of the tympanic cavity, mastoid cells, and auditory tube; presynaptic parasympathetic fibres also pass through the tympanic nerve via the lesser superficial petrosal nerve to the otic ganglion, where they synapse with postsynaptic fibres that continue to supply the parotid gland. Synonym: nervus tympanicus, Andersch's nerve, Jacobson's nerve. (05 Mar 2000) |
| anterior ampullar nerve | <anatomy, nerve> A branch of the utriculoampullar nerve that supplies the crista ampullaris of the anterior saemicircular duct. Synonym: nervus ampullaris anterior. (05 Mar 2000) |
| anterior antebrachial nerve | <anatomy, nerve> A branch of the median arising in elbow region, running on interosseous membrane, supplying the flexor pollicis longus, part of flexor digitorum profundus and the pronator quadratus muscles, as well as radiocarpal and intercarpal joints. Synonym: nervus interosseus anterior, ramus profundus nervi radialis, nervus antebrachii anterior, anterior antebrachial nerve, volar interosseous nerve. (05 Mar 2000) |