anulus

anulus /anu·lus/ (an´u-lus) pl. a´nuli   [L.] a small ring or encircling structure; spelled also annulus.

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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.

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an·u·lus (ny-ls)

n.

Variant of annulus.

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anulus

see annulus.

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annulus, anulus

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

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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.