Histology Embryology MUscularis extern到 inner circular and outer longitudinal upper 1/3: skeletal muscle middle 1/3: mixed of skeletal I muscle and smooth muscle Smooth uscle lower 1/3: smooth muscle Tunien adventitia Esophageal a fibrous coat of loose connective tissue SkeletalMuscularis externa: • inner circular and outer longitudinal • upper 1/3: skeletal muscle • middle 1/3: mixed of skeletal muscle and smooth muscle • lower 1/3: smooth muscle Tunica adventitia: a fibrous coat of loose connective tissue