Anatomical Location of the Thyroid Gland
The thyroid gland is located in the lower anterior portion of the neck, extending from the level of the fifth cervical vertebra down to the first thoracic vertebra (C5-T1). 1
Detailed Anatomical Position
The thyroid gland has a distinctive butterfly shape with the following anatomical relationships:
- Position: Located in the lower anterior neck between C5 and T1 vertebral levels 1
- Anterior relations: Deep to the cervical strap muscles 2
- Posterior relations: Anterior to the trachea and esophagus 2
- Superior relation: Inferior to the thyroid cartilage 2
- Weight: Approximately 15-20g in adults 3
Structural Components
The thyroid gland consists of:
- Two lateral, nearly symmetrical lobes
- A connecting isthmus
- Pyramidal lobe (when present) - a conical or cylindrical projection that extends superiorly toward the thyroid cartilage or hyoid bone, most commonly originating from the isthmus and located to the left of the midline 4
Clinical Significance of Thyroid Location
The anatomical position of the thyroid gland has important surgical implications:
Nerve relationships: The recurrent laryngeal nerve (RLN) is intimately associated with the posterior aspect of bilateral thyroid lobes, while the external branch of the superior laryngeal nerve (EBSLN) is closely associated with the superior pole of the thyroid 2
Vascular considerations: The superior thyroid artery is approximately 4.4±0.5 mm from the midline at the level of the laryngeal prominence and 3.1±0.6 mm from the midline at the inferior border of the thyroid cartilage 5
Surgical approach: Knowledge of the thyroid's position relative to surrounding structures is critical during thyroidectomy to avoid injury to vital structures, particularly the recurrent laryngeal nerve 2
Anatomical Variations
- Pyramidal lobe: May be absent in up to 50% of cases 4
- Ectopic thyroid tissue: Can occasionally be found in the mediastinum, including intrathymic locations 6
- Vascular variations: The superior thyroid artery arises independently from the external carotid artery in 83.3% of cases, but may also arise from thyrolingual or linguofacial trunks in 16.7% of cases 5
Understanding the precise vertebral level location (C5-T1) of the thyroid gland is essential for proper surgical planning, imaging interpretation, and radiation protection considerations.