| dilator iridis | <anatomy> The radial muscular fibres extending from the sphincter pupillae to the ciliary margin; some anatomists regard them as elastic, not muscular, in humans. Synonym: musculus dilator pupillae, dilator iridis, dilator of pupil, musculus dilator iridis. (05 Mar 2000) |
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| facies anterior iridis | The anterior surface of the iris of the eye. Synonym: facies anterior iridis. (05 Mar 2000) |
| facies posterior iridis | The posterior surface of the iris. Synonym: facies posterior iridis. (05 Mar 2000) |
| ligamentum pectinatum iridis | Pectinate ligaments of iridocorneal angle. See: trabecular reticulum. (05 Mar 2000) |
| annulus | Ring like structure, adj. Annulate. (18 Nov 1997) |
| annulus abdominalis | The opening in the transversalis fascia through which the ductus deferens (or round ligament in the female) and gonadal vessels enter the inguinal canal. Located midway between anterior superior iliac spine and pubic tubercle, it is bounded medially by the lateral umbilical ligament (inferior epigastric vessels) and inferiorly by the inguinal ligament. Indirect inguinal hernias exit the abdominal cavity via the deep inguinal ring Synonym: annulus inguinalis profundus, abdominal ring, annulus abdominalis, internal inguinal ring. (05 Mar 2000) |
| annulus ciliaris | <anatomy> Tissue that includes the group of muscles that act on the eye lens to produce accommodation and the arterial circle of the iris. The inner ciliary epithelium is continuous with the pigmented retinal epithelium, the outer ciliary epithelium secretes the aqueous humour. (18 Nov 1997) |
| annulus conjunctivae | A narrow ring at the junction of the periphery of the cornea with the conjunctiva. Synonym: annulus conjunctivae. (05 Mar 2000) |
| annulus femoralis | The superior opening of the femoral canal, bounded anteriorly by the inguinal ligament, posteriorly by the pectineus muscle, medially by the lacunar ligament, and laterally by the femoral vein. Passageway by which many lymphatics from lower limb pass to abdomen. Accommodates enlargement of femoral vein in Valsalva manoeuvre. Often occupied by a lymph node (Cloquet's) and is the site of femoral hernias. Synonym: annulus femoralis, crural ring. (05 Mar 2000) |
| annulus fibrocartilagineus membranae tympani | fibrocartilaginous ring of tympanic membrane |
| annulus fibrosus | 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) |
| annulus fibrosus cordis | 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) |
| annulus fibrosus disci intervertebralis | 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) |
| annulus fibrosus 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) |
| annulus haemorrhoidalis | The part of the anal canal that contains the rectal venous plexus. Synonym: annulus haemorrhoidalis, zona haemorrhoidalis. (05 Mar 2000) |