Muscles forming boundaries of carotid triangle are all except
Boundaries of carotid triangle are :

Anterosuperiorly – posterior belly of digastric.
Anteroinferiorly – superior belly of omohyoid.
Posteriorly – sternocleidomastoid muscle.
Posterior belly of digastric
Superior belly of omohyoid
Inferior belly of omohyoid
Sternocleidomastoid