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.