| axis opticus | The axis of the eye connecting the anterior and posterior poles; it usually diverges from the visual axis by five degrees or more. Synonym: axis opticus. (05 Mar 2000) |
|---|---|
| canalis opticus | The short canal through the lesser wing of the sphenoid bone at the apex of the orbit that gives passage to the optic nerve and the ophthalmic artery. Synonym: canalis opticus, foramen opticum, optic foramen. (05 Mar 2000) |
| recessus opticus | A diverticulum extending forward from the anterior part of the third ventricle above the optic chiasm. Synonym: recessus opticus. (05 Mar 2000) |
| porus opticus | The portion of the optic nerve seen in the fundus with the ophthalmoscope. It is formed by the meeting of all the retinal ganglion cell axons as they enter the optic nerve. Because the retina at the optic disk has no photoreceptors there is a corresponding blind spot in the visual field. (12 Dec 1998) |
| nervus opticus | <anatomy, nerve> The optic nerve. The nerve carrying impulses for the sense of sight. Projection from the vertebrate retina to the midbrain. Embryologically, a CNS tract rather than a peripheral nerve. Popular experimental preparation for studies of regeneration of retino tectal projections in lower vertebrates and also for studies of glial cell lineage in CNS. Synonym: cranial nerve II. (18 Nov 1997) |
| tractus opticus | The continuation of the optic nerve fibres beyond (behind) the latter's hemidecussation in the optic chiasm; each of the two symmetrical optic tracts is composed of fibres originating from the temporal half of the retina of the ipsilateral eye and a nearly equal number of fibres from the nasal half of the contralateral retina; it forms a compact, somewhat flattened fibre band passing caudolaterally alongside the base of the hypothalamus and over the basal surface of the crus cerebri; most of its fibres terminate in the lateral geniculate body; a smaller number of fibres enter the brachium of the superior colliculus, to terminate in the superior colliculus and the pretectal region. Synonym: tractus opticus. (05 Mar 2000) |
| anterior pyramidal fasciculus | Uncrossed fibres forming a small bundle in the pyramidal tract. See: pyramidal tract. Synonym: tractus corticospinalis anterior, tractus pyramidalis anterior, anterior corticospinal tract, anterior pyramidal fasciculus, direct pyramidal tract, fasciculus corticospinalis anterior, fasciculus pyramidalis anterior, Turck's bundle, Turck's column, Turck's tract. (05 Mar 2000) |
| arcuate fasciculus | Long association fibre bundle lateral to the centrum ovale of the cerebral hemisphere, connecting the frontal, occipital, and temporal lobes; the fibres pass from the frontal lobe through the operculum to the posterior end of the lateral sulcus where many fibres radiate into the occipital lobe and others turn downward and forward around the putamen and pass to anterior portions of the temporal lobe. Synonym: fasciculus longitudinalis superior, arcuate fasciculus. (05 Mar 2000) |
| Burdach's fasciculus | The larger lateral subdivision of the posterior funiculus. Synonym: fasciculus cuneatus, Burdach's column, Burdach's fasciculus, Burdach's tract, cuneate funiculus, wedge-shaped fasciculus. (05 Mar 2000) |
| calcarine fasciculus | A group of short association fibres beneath the calcarine fissure of the occipital lobe of the cerebrum. (05 Mar 2000) |
| macular fasciculus | The collection of fibres in the optic nerve directly connected with the macula lutea. Synonym: fasciculus macularis. (05 Mar 2000) |
| mamillotegmental fasciculus | A small bundle of fibres that passes dorsalward from the mamillary body for a short distance with the mamillothalamic tract, then turns down the brainstem to reach the dorsal and ventral tegmental nuclei of the mesencephalon. Synonym: fasciculus mamillotegmentalis. (05 Mar 2000) |
| mamillothalamic fasciculus | A compact, thick bundle of nerve fibres that passes dorsalward from the mamillary body on either side to terminate in the anterior nucleus of the thalamus. Synonym: fasciculus mamillothalamicus, fasciculus thalamomamillaris, mamillothalamic tract, Vicq d'Azyr's bundle. (05 Mar 2000) |
| marginal fasciculus | A longitudinal bundle of thin, unmyelinated and poorly myelinated fibres capping the apex of the posterior horn of the spinal gray matter, composed of posterior root fibres and short association fibres that interconnect neighboring segments of the posterior horn. Synonym: fasciculus dorsolateralis, tractus dorsolateralis, dorsolateral tract, fasciculus marginalis, Lissauer's bundle, Lissauer's column, Lissauer's fasciculus, Lissauer's marginal zone, Lissauer's tract, marginal fasciculus, Spitzka's marginal tract, Spitzka's marginal zone, Waldeyer's tract, Waldeyer's zonal layer. (05 Mar 2000) |
| medial longitudinal fasciculus | A longitudinal bundle of fibres extending from the upper border of the mesencephalon into the cervical segments of the spinal cord, located close to the midline and ventral to the central gray matter; it is composed largely of fibres from the vestibular nuclei ascending to the motor neurons innervating the external eye muscles (abducens, trochlear, and oculomotor nuclei), and descending to spinal cord segments innervating the musculature of the neck. Synonym: fasciculus longitudinalis medialis, Collier's tract, medial longitudinal bundle, posterior longitudinal bundle. (05 Mar 2000) |