| ION | ischemic optic neuropathy |
|---|---|
| IOT | intraocular tension; intraocular transfer; ipsilateral optic tectum |
| 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 |
| fibrous ring of heart | One of four fibrous rings that surround atrioventricular and arterial orifices of the heart, providing attachment for the valve leaflets and maintaining patency of the orifice. As part of the fibrous skeleton of the heart, the fibrous rings also provide origin and insertion for the myocardium. Synonym: annulus fibrosus cordis, annulus fibrosus, coronary tendon, fibrous ring, Lower's ring. (05 Mar 2000) |
|---|---|
| fibrous ring of intervertebral disc | The ring of fibrocartilage and fibrous tissue forming the circumference of the intervertebral disc; surrounds the nucleus pulposus, which is prone to herniation when the annulus fibrosus is compromised. Synonym: annulus fibrosus disci intervertebralis, annulus fibrosus, fibrous ring of intervertebral disc, fibrous ring. (05 Mar 2000) |
| fibrous sheaths | See: fibrous tendon sheath, fibrous digital sheaths of hand, fibrous digital sheaths of foot. (05 Mar 2000) |
| fibrous skeleton of heart | A complex framework of dense collagen forming four fibrous rings (annuli fibrosi), which surround the ostia of the valves, a right and left fibrous trigone, formed by connecting the rings, and the membranous portions of the interatrial and interventricular septa; it is found in association with the base of the ventricles, i.e., at the level of the coronary sulcus; its functions include: 1) contributing reinforcement of the valvular ostia while providing attachment for the leaflets and cusps of the valves; 2) providing origin and insertion for the myocardium; and 3) serving as a sort of electrical "insulator," separating the electrically conducted impulses of the atria and ventricles and providing passage for the common atrioventricular bundle of conductive tissue through the right fibrous trigone and membranous interventricular septum. Synonym: cardiac fibrous skeleton, cardiac skeleton, skeleton of heart. (05 Mar 2000) |
| fibrous tissue | Although most connective tissue has fibrillar elements, the term usually refers to tissue laid down at a wound site well vascularised at first (granulation tissue) but later avascular and dominated by collagen rich extracellular matrix, forming a scar. Excessive contraction and hyperplasia leads to formation of a keloid. (18 Nov 1997) |
| fibrous trigones of heart | See: right fibrous trigone, left fibrous trigone. (05 Mar 2000) |
| fibrous tubercle | A tubercle in which fibroblasts proliferate about the periphery (and into the cellular zones), eventually resulting in a rim or wall of cellular fibrous tissue or collagenous material around the tubercle. (05 Mar 2000) |
| fibrous tunic of corpus spongiosum | <anatomy> The thick layer of fibrous tissue surrounding the corpus spongiosum penis. It is thinner than the corresponding layer around each corpus cavernosum. Synonym: tunica albuginea corporis spongiosi, fibrous tunic of corpus spongiosum. (05 Mar 2000) |
| fibrous tunic of eye | The outer layer of the eyeball composed of the sclera and cornea. Synonym: tunica fibrosa bulbi, tunica externa oculi. (05 Mar 2000) |
| fibrous union | Union of fracture by fibrous tissue. See: nonunion. Synonym: faulty union. (05 Mar 2000) |
| fibrous xanthoma | <tumour> A fibrohistiocytic neoplasm. (05 Mar 2000) |
| left fibrous trigone | The part of the fibrous skeleton of the heart located in the interval between the left side of the left atrioventricular ring and the aortic ring. Synonym: trigonum fibrosum sinistrum. (05 Mar 2000) |
| axis, optic | <microscopy> The direction, or directions in an anisotropic crystal along which light is not doubly refracted. (05 Aug 1998) |
| glioma of optic chiasm | A slow-growing tumour, usually an astrocytoma, of the optic chiasm in children. (05 Mar 2000) |
| medial root of optic tract | The smaller division of the posterior end of the optic tract that disappears under the medial geniculate body. Synonym: radix medialis tractus optici. (05 Mar 2000) |