anulus

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anulus

 [an´u-lus] (pl. a´nuli) (L.)
a small ring or encircling structure; also spelled annulus.
anulus fibro´sus
1. fibrous ring of heart; any of four dense fibrous rings, one of which surrounds each of the major cardiac orifices.
2. fibrous ring of intervertebral disk; the circumferential ringlike portion of an intervertebral disk.
anulus of spermatozoon a dark ringlike structure at the posterior end of the middle piece of a spermatozoon. Called also ring centriole.

ring

(ring), [TA]
1. A circular band surrounding a wide central opening; an anular or circular structure surrounding an opening or level area. Synonym(s): anulus [TA]
2. The closed (that is, endless) chain of atoms in a cyclic compound; commonly used for "cyclic" or "cycle."
3. A marginal growth on the upper surface of a broth culture of bacteria, adhering to the sides of the test tube in the form of a circle.
Synonym(s): anulus
[A.S. hring]

anulus

/anu·lus/ (an´u-lus) pl. a´nuli   [L.] a small ring or encircling structure; spelled also annulus.
anulus fibro´sus 
1. fibrous ring of heart: one of the dense fibrous rings that surround the right and left atrioventricular (tricuspid and mitral) orifices and to which are attached the atrial and ventricular muscle fibers.
2. fibrous ring of intervertebral disk; the circumferential ringlike portion of an intervertebral disk.
anulus of nuclear pore  a circular filamentous structure surrounding a nuclear pore in the nuclear membrane of a cell.
anulus of spermatozoon  an electron-dense body at the caudal end of the neck of a spermatozoon.

anulus

[an′yələs]
a ring of circular tissue, such as the whitish tympanic anulus around the perimeter of the tympanic membrane. Also spelled annulus. annular, anular, adj.

ring

(ring) [TA]
1. Anular or circular structure surrounding an opening or level area.
Synonym(s): anulus [TA] .
2. anatomy Anulus.
3. The closed chain of atoms in a cyclic compound; commonly used for "cyclic" or "cycle."
4. A marginal growth on the upper surface of a broth culture of bacteria, adhering to the sides of the test tube in the form of a circle.

anulus

see annulus.

annulus, anulus

pl. annuli, anuli [L.] a small ring or encircling structure.

atrioventricular annulus
a ring of Purkinje cells around the right A-V orifice that serves the myocardium and valves locally and also serves as an alternative connection between the atria and the ventricles.
fibrocartilaginous annulus
the circular pad which connects the tympanic membrane to the external acoustic meatus.
annuli fibrosi
1. four fibrous rings at the base of the heart to which the myocardium is attached, one around each A-V orifice and one each around the aorta and the pulmonary artery.
2. the intervertebral disks consist of a soft central pulpy nucleus and a peripheral annulus fibrosus.
annulus iridis
the iris consists of two rings, an inner smooth annulus iridus minoris, and an outer plicated part, the annulus iridis major.
annulus preputialis
the ring of skin marking the entrance to the cavity of the prepuce.
annulus sclerae
a roll of connective tissue on the inside of the sclera at the corneoscleral junction.
spermatic annulus
a small ring condenses around the proximal centriole of the spermatid.
annulus vaginalis
the ring through which the peritoneal cavity connects with the cavity of the vaginal tunic.