Chair

1. A chair comprising a chair base, a seat part connected thereto, a backrest connected thereto, wherein the seat part is freely pivotable about at least one horizontal or inclined horizontal axis, wherein the seat part has a seat surface for a buttocks region and at least three independently adjustable seat elements for a thigh region of a person sitting on the chair, the operating positions of which are individually adjustable, and that the horizontal pivot axis of the seat part is arranged approximately centrally above the seat surface of the seat part, wherein a joint is arranged on the chair base and connects the seat part to the chair base in a freely swinging manner and whereby the horizontal pivot axis is approximately coaxial with a hip joint axis of the person.

2. The chair according to claim 1 , wherein the backrest is spatially adjustable, wherein a receptacle of the backrest, which extends at least in regions along the backrest, has a plurality of swivel elements which are arranged one above the other and are connected to one another in an articulated manner.

3. The chair according to claim 1 , wherein either the seat part and the backrest are pivotable and lockable about a second common horizontal or inclined horizontal axis which is arranged perpendicular to the first common horizontal or inclined horizontal axis, or the seat part about a third and the backrest about at least a fourth horizontal or inclined horizontal axis which are independent of each other and perpendicular to the second and third horizontal or inclined horizontal axes.

4. A chair comprising a chair base, a seat part connected thereto, a backrest connected thereto, wherein the seat part is pivotable about at least one horizontal or inclined horizontal axis, wherein the seat part has a seat surface for a buttocks region and at least three independently adjustable seat elements for a thigh region of a person sitting on the chair, the operating positions of which are individually adjustable, and that the horizontal pivot axis of the seat part is arranged approximately centrally above the seat surface of the seat part, whereby the horizontal pivot axis is approximately coaxial with a hip joint axis of the person, wherein the seat part has a seat shell with seat leg recesses, a seat cushion, a saddle curvature and leg supports, the seat cushion being arranged in the seat shell and/or in that the saddle curvature and the leg supports are connected to the seat shell and/or that the saddle curvature and the leg supports are pivotable and lockable about a common horizontal or inclined horizontal axis, and/or the saddle curvature and the leg supports are pivotable and lockable independently of each other.

5. The chair according to claim 4 , wherein the seat part is connected to the chair base by a base arm connected to the chair base at at least a first end thereof, a tilt module

connected to at least a first end thereof to a further end or a portion of the base arm, and a seat arm connected to a first end or a portion to a further end or a portion of the tilt module, wherein at least one further end of the seat arm is connected to at least one first end of a back arm and wherein the at least first end of the back arm is connected to at least one first end of the seat shell, and wherein a further end or a section of the back arm is connected to an end of the backrest and a sacral support.

6. The chair according to claim 5 , wherein the base arm can be pivoted and locked relative to the chair base about a horizontal or inclined horizontal axis and/or

in that the inclination module can be pivoted and locked relative to the base arm about a horizontal or inclined horizontal axis and/or that the seat arm is pivotable and lockable relative to the tilt module about a horizontal or inclined horizontal axis arranged perpendicular to the axis between the base arm and the tilt module, and/or that the back arm relative to the seat arm and the seat shell independently of each other or the seat shell relative to the seat arm and the back arm independently of each other are pivotable and lockable about a horizontal or inclined horizontal axis.

7. The chair according to claim 1 , wherein the chair has a headrest which is spatially adjustable.

8. A chair comprising a chair base, a seat part connected thereto, a backrest connected thereto, wherein the seat part is pivotable about at least one horizontal or inclined horizontal axis, wherein the seat part has a seat surface for a buttocks region and at least three independently adjustable seat elements for a thigh region of a person sitting on the chair, the operating positions of which are individually adjustable, and that the horizontal pivot axis of the seat part is arranged approximately centrally above the seat surface of the seat part, whereby the horizontal pivot axis is approximately coaxial with a hip joint axis of the person, wherein the headrest comprises an end vertebra connected with a first end to a further end of the backrest and a head support connected to a further end of the end vertebra, and that the head support is displaceable along a vertical or inclined vertical guide of the end vertebra and is pivotable and lockable about a horizontal or inclined horizontal axis perpendicular to the guide.