Synonym for carotid sheath ... The dense fibrous investment of the carotid artery, internal jugular vein, and vagus nerve on each side of the neck, deep to the sternocleidomastoid muscle; the layers of cervical fascia blend with it. ... Synonym: vagina carotica. ... (05 Mar 2000) ... Found on http://www.encyclo.co.uk/local/20973