The left lobe of the thyroid is located anterolateral to the esophagus. On transverse ultrasound imaging, the esophagus can often be seen posterior to the left thyroid lobe as a circular structure with echogenic mucosa and hypoechoic muscular layer. The longus colli muscle lies posterior to the thyroid. The thyroid is anterior to the trachea but this refers more to the isthmus or midline portion.

According to Rumack’s Diagnostic Ultrasound:

“The esophagus is seen as a target-shaped structure posterior to the left thyroid lobe; thus, the thyroid lobe is anterolateral to the esophagus.”