| IOT | intraocular tension; intraocular transfer; ipsilateral optic tectum |
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| LHON | Leber hereditary optic neuropathy |
| LOA | leave of absence; Leber optic atrophy; left occipitoanterior [fetal position] |
| MOD | magnetic optic disk; maturity onset diabetes; Medical Officer of the Day; mesio-occlusodistal |
| OA | obstructive apnea; occipital artery; occipito-anterior; occiput anterior; octanoic acid; ocular albi... |
| optic recess | A diverticulum extending forward from the anterior part of the third ventricle above the optic chiasm. Synonym: recessus opticus. (05 Mar 2000) |
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| optic sign | <microscopy> For uniaxial materials, by definition, the sign is positive if the value epsilon minus omega is positive, and negative if epsilon - omega is negative. For biaxial materials, the sign is positive if gamma is the acute bisectrix, and negative if alpha is the acute bisectrix, or positive if gamma - beta greater than beta - alpha and negative if gamma - beta less than beta - alpha (05 Aug 1998) |
| optic stalk | The constricted proximal portion of the optic vesicle in the embryo; it develops into the optic nerve. Pineal stalk, the attachment of the pineal body to the roof of the third ventricle; it contains the pineal recess of the third ventricle. Pituitary stalk, a process comprising the tuberal part investing the infundibular stem that attaches the hypophysis to the tuber cinereum at the base of the brain. Yolk stalk, the narrowed connection between the intraembryonic gut and the yolk sac; its walls are splanchnopleure. Synonym: umbilical duct, vitelline duct, vitellointestinal duct. (05 Mar 2000) |
| optic tectum | <anatomy> A region of the midbrain in which input from the optic nerve is processed. Because the retinally derived neurons of the optic nerve map onto the optic tectum in a defined way, the question of how this specificity is determined has been a long standing problem in cell biology. Although there is some evidence for adhesion gradients and for some adhesion specificity, the problem is unresolved. (11 Jan 1998) |
| optic tract | 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) |
| optic vesicle | In the embryo, one of the paired evaginations from the ventrolateral walls of the forebrain from which the sensory and pigment layers of the retina develop. Synonym: vesicula ophthalmica, ocular vesicle, optic vesicle. (05 Mar 2000) |
| lateral root of optic tract | The larger division of the posterior end of the optic tract that terminates in the lateral geniculate body. Synonym: radix lateralis tractus optici. (05 Mar 2000) |
| Leber's hereditary optic atrophy | Hereditary degeneration of the optic nerve and papillomacular bundle with resulting rapid loss of central vision, progressive for several weeks, then usually stationary with permanent central scotoma; age of onset is variable, most often in the third decade; more males than females are affected and transmission is cytoplasmic and strictly on the female side. Mutation on the mitochondrial chromosome involved, which presumably interacts with an X-linked mutant. This mechanism may explain the bizarre sex ratio, which differs significantly from one country to another. (05 Mar 2000) |
| lenticulo-optic | Relating to the lentiform nucleus and the optic tract; specifically refers to branches of the middle cerebral artery considered to supply these structures. (05 Mar 2000) |
| absorber head | Portion of a rebreathing anaesthesia circuit that contains carbon dioxide absorbent; often referred to as a canister. (05 Mar 2000) |
| anterior ligament of head of fibula | A ligament uniting the anterior part of the head of the fibula to the tibia. Synonym: ligamentum capitis fibulae anterius. (05 Mar 2000) |
| anterior rectus muscle of head | <anatomy, muscle> Origin, transverse process and lateral mass of atlas; insertion, basilar process of occipital bone; action, turns and inclines head forward; nerve supply, ventral primary ramus of first and second cervical spinal nerve. Synonym: musculus rectus capitis anterior, anterior rectus muscle of head, musculus rectus capitis anticus minor. (05 Mar 2000) |
| apex of head of fibula | The pointed upper end of the fibular head to which is attached the arcuate popliteal ligament and part of the biceps femoris tendon. Synonym: apex capitis fibulae, styloid process of fibula. (05 Mar 2000) |
| articular pit of head of radius | The depression on the top (superior surface) of the head of the radius for articulation with the capitulum of the humerus. Synonym: fovea articularis capitis radii, articular pit of head of radius. (05 Mar 2000) |
| articular surface of head of fibula | The flat circular surface on the head of the fibula for articulation with the corresponding facet on the lateral condyle of the tibia. Synonym: facies articularis capitis fibulae. (05 Mar 2000) |