Central point, knob, or nob

noun

1. A pathological swelling or enlargement (as of a rheumatic joint)
2. A discrete mass of one kind of tissue enclosed in tissue of a different kind
3. An entangling complication (as in a drama) predicament
4. Either of the two points where the orbit of a planet or comet intersects the ecliptic
5. A point, line, or surface of a vibrating body or system that is free or relatively free from vibratory motion
6. A point at which a wave has an amplitude of zero
7. A point at which subsidiary parts originate or center
8. A point on a stem at which a leaf or leaves are inserted
9. A point at which a curve intersects itself in such a manner that the branches have different tangents
10. Vertex

noun phrase

1. A small gap in the myelin sheath of a myelinated nerve fiber

noun

1. Castleman disease

noun

1. A small mass of tissue in the right atrioventricular region of higher vertebrates through which impulses from the sinus node are passed to the ventricles

noun

1. Atrioventricular node

noun

1. Castleman disease

noun

1. Any of the rounded masses of lymphoid tissue that are surrounded by a capsule of connective tissue, are distributed along the lymphatic vessels, and contain numerous lymphocytes which filter the flow of lymph passing through the node

noun

1. Kawasaki disease

   "Kawasaki disease (KD), also known as mucocutaneous lymph node syndrome, is an acute systemic vasculitis seen in the pediatric population."

noun

1. Sinus node

noun

1. A small mass of tissue that is embedded in the musculature of the right atrium of higher vertebrates and that originates the impulses stimulating the heartbeat