This exhaust manifold comprises: an outer envelope comprising: at least one flange connected to the outer shell and having at least one gas circulation port, the outer envelope having at least one gas circulation port; at least one internal duct (31) arranged inside the outer envelope and opening via a gas circulation port, characterized in that: the or each internal duct (31) is formed, at least for the most part of its length, of a ceramic material and is engaged through the or each port; and it comprises an annular diaphragm (34) that is impermeable to the gases but radially and axially elastically deformable and positioned around the or each internal duct (31), between the or each internal duct (31) and the outer envelope (18), the diaphragm (34) being connected at its periphery to at least one out of the outer envelope (18) and the or each internal duct (20, 31).