Carotid sheath sternum. The four major structures contained in the carotid sheath are: The carotid artery lies medial to the internal jugular vein, and the vagus nerve is situated posteriorly between the two vessels. In the upper part, the carotid sheath also contains the glossopharyngeal nerve (IX), the accessory nerve (XI), and the hypoglossal nerve (XII), which pierce the fascia of the carotid sheath. The ansa cervicalis is embedded in the anterior wall of sheath. It is formed by "descendens hypoglossi" (C1) and "descendens cervicalis" (C2-C3). The three major fascial layers in the neck contribute to the carotid sheath: the investing fascia,
Intima-media thickness not satisfactory. IMT can be measured using external ultrasound in large arteries relatively close to the skin (e.g. the carotid, brachial, radial, or femoral arteries). External ultrasound methods have the advantage of being non-invasive, comparatively low cost and convenient. Deeper internal arteries, such as the coronary arteries require special intravascular catheters employing ultrasound or optical coherence tomography to measure IMT. The carotid artery is the usual site of measurement of IMT and consensus statements for carotid IMT have been published for adults and children. Often, IMT is measured in three locations: in the common carotid artery (typically at one cm