def get_backbone_atoms(structure):
    """
    Return the backbone atoms of the specified structure.

    Parameters
    ----------
    structure : Bio.PDB.Structure
        The structure.

    Returns
    -------
    list of Bio.PDB.Atom
        The backbone atoms.
    """
    atoms = []
    for model in structure:
        for chain in model:
            for residue in chain:
                if 'CA' in residue:
                    atoms.append(residue['CA'])
                if 'C' in residue:
                    atoms.append(residue['C'])
                if 'N' in residue:
                    atoms.append(residue['N'])
    return atoms