There are many types of coronal consonants , for example dental consonants and alveolar consonants . Coronal places of articulation include the dental consonants at the upper teeth , the alveolar consonants at the upper gum ( the alveolar ridge ) , the various postalveolar consonants ( domed palato-alveolar , laminal alveolo-palatal , and apical retroflex ) just behind that , the true retroflex consonants curled back against the hard palate , and linguolabial consonants with the tongue against the upper lip .