Mesoscopic and microscopic study of the carotid sheath.

In this work, the author carried out mesoscopic and microscopic studies of the human carotic sheath in order to verify its existence, constitution, mode of attachment and the real appearance of its initial portion near the first portion of the internal jugular vein; the surrounding connective tissue formations which attach this vessel to the carotid sheath were studied as well. In 40 anatomical specimens of both sides, microscopic examination revealed that the carotid sheath is always present; it constitutes a complete cover around the neurovascular complex and presents subdivisions which envelop the internal jugular vein, the internal carotid artery and the glossopharyngeal, vagus, external branches of the accessory and internal carotid nerves. Mesoscopic inspection showed that fascicles of conjunctive fibers connect the wall of the first portion of the internal jugular vein with the internal face of the carotid sheath; and that fibrous prolongations superiorly fix the carotid sheath to the border of the jugular foramen and carotid canal. Microscopically, the carotid sheath has a fibroelastic constitution and its walls are of variable thickness.