True regarding surface anatomy of internal jugular vein -

SURFACE MARKINGS OF IMPORTANT VESSELS OF NECK Surface anatomy of internal jugular vein: Internal jugular vein is marked by a line joining a point on the neck, medial to the ear lobule to a point at the medial end of the clavicle Surface anatomy of the external jugular vein: Marked by a line joining a point a little below and behind the angle of the mandible to a point on the clavicle just lateral to the posterior border of the sternocleidomastoid. Common carotid artery: Marked by a line joining a point on the sternovlavicular joint to a point on the anterior border of the sternocleidomastoid at the level of upper border of the thyroid cartilage. Internal carotid artery: Marked by a line joining a point on the anterior border of the sternocleidomastoid at the level of upper border of thyroid cartilage to a point on the posterior border of the condyle of the mandible. External carotid artery: Marked by a line joining a point on the anterior border of the stemocleidomastoid at the level of upper border of thyroid cartilage to a point on the posterior border of the neck of the mandible.