An attachment assembly includes an elongate channel element and a male fastening element including a shank to fasten the channel element to another structural element. The elongate channel element has a substantially flat bottom, sidewalls extending from the bottom substantially at right angles and an upper side opposite the bottom. The upper side of the channel element includes flanges which extend from the respective sidewalls towards each other and delimit between them a longitudinal slot extending over the length of the channel element. The bottom has an aperture formed in it for passing through the shank of the male fastening element. The male fastening element has a head that has a circular groove in the side where the shank is located. The groove in the head is engageable with a collar surrounding the aperture so as to mutually lock the head and the bottom in position at the aperture.