Ultrasound (US)-guided interventions of the thyroid gland, including radiofrequency and other thermal ablation techniques, require operator experience with US-based anatomic assessment of the thyroid and surrounding critical structures. Operators need to identify anatomic landmarks for a safe ablation. The identification of the nerves, vessels, and other critical structures is essential. The knowledge of cross-sectional head and neck anatomy will facilitate US performance. Therefore, the purposes of this chapter will be to describe US-based anatomy of the neck with specific attention to the thyroid and its surroundings in infrahyoid region of the neck, describing the anatomy and the US features of the structures located in the visceral, anterior cervical, posterior cervical, carotid, retropharyngeal, and perivertebral spaces. Knowledge of these areas may be helpful for maximizing the efficacy and minimizing the complications of US-guided procedures.