sinoatrial node

node (nōd) a small mass of tissue in the form of a swelling, knot, or protuberance, either normal or pathological.no´dal

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atrioventricular node , AV node (AVN) a collection of Purkinje fibers beneath the endocardium of the right atrium, continuous with the atrial muscle fibers and atrioventricular bundle; it receives the cardiac impulses from the sinoatrial node and passes them on to the ventricles.

Bouchard's nodes  cartilaginous and bony enlargements of the proximal interphalangeal joints of the fingers in degenerative joint disease.

Dürck's nodes  granulomatous perivascular infiltrations in the cerebral cortex in trypanosomiasis.

Flack's node  sinoatrial n.

Heberden's nodes  small hard nodules, usually at the distal interphalangeal joints of the fingers, formed by calcific spurs of the articular cartilage and associated with osteoarthritis.

Hensen's node  primitive node.

Keith's node , Keith-Flack node sinoatrial n.

lymph node  any of the accumulations of lymphoid tissue organized as definite lymphoid organs along the course of lymphatic vessels, consisting of an outer cortical and an inner medullary part; they are the main source of lymphocytes of the peripheral blood and, as part of the reticuloendothelial system, serve as a defense mechanism by removing noxious agents, e.g., bacteria and toxins, and probably play a role in antibody formation.

Lymph node (nodus lymphoideus).

Osler's nodes  small, raised, swollen, tender areas, bluish or sometimes pink or red, occurring commonly in the pads of the fingers or toes, in the thenar or hypothenar eminences, or the soles of the feet; they are practically pathognomonic of subacute bacterial endocarditis.

primitive node  a mass of cells at the cranial end of the primitive streak in the early embryo.

nodes of Ranvier  constrictions of myelinated nerve fibers at regular intervals at which the myelin sheath is absent and the axon is enclosed only by Schwann cell processes.

Schmorl's node  an irregular or hemispherical bone defect in the upper or lower margin of the body of a vertebra.

sentinel node 

1. the first lymph node to receive drainage from a tumor; used to determine whether there is lymphatic metastasis in certain types of cancer.

2. signal n.

signal node  an enlarged supraclavicular lymph node; often the first sign of a malignant abdominal tumor.

singer's nodes  vocal cord nodules.

sinoatrial node , sinuatrial node, sinus node a microscopic collection of atypical cardiac muscle fibers (Purkinje fibers) at the junction of the superior vena cava and right atrium, in which the cardiac rhythm normally originates and which is therefore called the cardiac pacemaker.

teacher's nodes  vocal cord nodules.

Troisier's node , Virchow's node signal n.

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sinoatrial node

n. Abbr. SAN

A small mass of specialized cardiac muscle fibers located in the posterior wall of the right atrium of the heart that acts as a pacemaker of the cardiac conduction system by generating at regular intervals the electric impulses of the heartbeat. Also called sinoauricular node, sinus node.

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sinoatrial node.

See sinus node.

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sinoatrial

pertaining to the sinus venosus and the atrium of the heart or to the sinoatrial node; abbreviated S-A, SA.

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sinoatrial block

an absence of a discharge from the sinoatrial node. The heart is regular unless there is an underlying atrial arrhythmia. Considered to be within the limits of normality provided it disappears with exercise.

sinoatrial node

a collection of atypical muscle fibers and nerve endings in the wall of the right atrium, adjacent to the sulcus terminalis, where the rhythm of cardiac contraction is usually established; therefore also referred to as the pacemaker of the heart. Called also sinoatrial bundle, Keith's node, Keith-Flack node.

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sinoatrial node

SA node, sinuatrial node, sinus node, heart's pacemaker Anatomy A knot of specialized, spontaneously depolarizing cells located at the posterior wall of the upper right atrium, in the sulcus terminalis at the junction between the superior vena cava and right atrium, the heart's natural pacemaker Normal rhythm 70/min; conducts impulses via 3 Purkinje fiber tracts: (1) anterior internodal tract of Bachman; (2) middle internodal tract of Wenckebach; (3) posterior internodal tract of Thorel to AV node–normal rhythm, 45/min–in right posterior portion of interatrial septum; it is continuous with bundle of His–normal rhythm, 35/min Blood supply Rt coronary–65%, circumflex–25%, both in remainder Flow of impulse From the SN through right atrium to AV node in low septal right atrium. See Conduction system. Cf Atrioventricular node.