<prompt> All except one is true regarding carotid sheathCarotid sheath contains internal carotid artery, internal jugular vein, and vagus nerveIt is formed by investing layer of deep cervical fascia, pretracheal and prevertebral fasciaSympathetic chain runs vertically through the carotid sheath9,11, and 12th cranial nerves pierce the upper part of carotid sheath  <response>: Sympathetic chain runs behind the carotid sheath. 