ðə tˈɜːmɪnəl sˈʌlkəs ɪz ɐ ɡɹˈuːv ɔnðɪ ˈaʊɾɚ sˈɜːfɪs ʌvðə ɹˈaɪt ˈeɪtɹiəm ʌvðə hˈɑːɹt mˈɑːɹkɪŋ ðə tɹænsˈɪʃən bᵻtwˌiːn ðə sˈaɪnəs vˈɛnɑːɹɹəm kˈævɑːɹɹəm wˌɪtʃ hɐz ɐ dɪstˈɪŋkt ˌɛmbɹɪəlˈɑːdʒɪkəl ˈɔːɹɪdʒˌɪn ænd ðə ɹˈɛst ʌvðə ɹˈaɪt ˈeɪtɹiəm wˌɪtʃ fˈiːtʃɚz pˈɛktᵻnˌeɪt mˈʌsəlz ˌɔn ɪts ˈɪnɚ sˈɜːfɪs.
The terminal sulcus is a groove on the outer surface of the right atrium of the heart marking the transition between the sinus venarum cavarum (which has a distinct embryological origin) and the rest of the right atrium (which features pectinate muscles on its inner surface).