1. A brush assembly for an electric toothbrush with an electric drive, wherein the brush assembly has a head portion comprising: a frame including a first plurality of contact elements supported within a frame； a movable contact element holder including a second plurality of contact elements supported by a movable contact holder , while the holder of the movable contact elements has a design that allows him to take a cleaning movement from an electric drive, while having at least one degree of freedom of movement in relation to the first set of contact elements； the elongated part of the holder of movable contact elements located on the nose end of the head part, and there is a gap between the elongated part and the frame； at least the first part of the gap located in the lateral peripheral region of the head part is smaller in width than the second part of the gap located in the inner area of the head of the toothbrush. 2. The brush assembly according to claim 1, further comprising a third part of the gap on a peripheral side region opposite the first part of the gap, and wherein the third part of the gap is smaller in width than the second part of the gap. The brush assembly according to claim 1, further comprising at least one buffer element located on at least one of the following parts: the frame and the elongated part, and facing the gap. The brush assembly according to claim 3, wherein the buffer element is made of a first material, the frame or the elongated part on which the buffer element is located is made of a second material, and the first material is different1. Щеточный узел для электрической зубной щетки с электрическим приводом, при этом щеточный узел имеет головную часть, содержащую:раму, включающую первое множество контактных элементов, поддерживаемых внутри рамы；держатель подвижных контактных элементов, включающий второе множество контактных элементов, поддерживаемых держателем подвижных контактных элементов, при этом держатель подвижных контактн
