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Right lobe of thyroid gland

The right lobe of the thyroid gland is one of the two lateral lobes of the thyroid, a bilobed endocrine organ located in the anterior neck. It extends from the oblique line of the thyroid cartilage superiorly to the fifth or sixth tracheal ring inferiorly. The right lobe lies lateral to the trachea and esophagus, bounded medially by the isthmus, and laterally by the sternocleidomastoid and strap muscles. Posteriorly, it is closely related to the recurrent laryngeal nerve and parathyroid glands, structures of major surgical importance. The thyroid gland, including the right lobe, produces thyroid hormones (T3 and T4) and calcitonin, critical for metabolism and calcium regulation.

Synonyms

  • Right thyroid lobe

  • Lateral thyroid lobe (right)

Function

  • Produces thyroid hormones (T3, T4), regulating metabolism, growth, and development

  • Secretes calcitonin, contributing to calcium homeostasis

  • Serves as an important landmark in neck surgery due to its vascular and neural relations

Arterial Supply

  • Superior thyroid artery (branch of the external carotid artery)

  • Inferior thyroid artery (branch of the thyrocervical trunk)

  • Occasionally, the thyroid ima artery (anatomic variant, from brachiocephalic trunk or aortic arch)

Venous Drainage

  • Superior thyroid vein → internal jugular vein

  • Middle thyroid vein → internal jugular vein

  • Inferior thyroid vein → brachiocephalic vein

Nerve Supply

  • Sympathetic innervation via the cervical sympathetic chain (vasomotor, not secretomotor)

  • Parasympathetic fibers from the vagus nerve via the superior and recurrent laryngeal nerves (closely related but not functionally innervating secretion)

  • Secretory function is regulated by thyroid-stimulating hormone (TSH) from the anterior pituitary, not direct neural control

MRI Appearance

T1-weighted images:

  • Normal thyroid tissue shows intermediate signal intensity relative to muscle

  • Surrounded by hyperintense fat planes, aiding boundary identification

  • Multinodular goiter, cysts, or tumors may appear as signal heterogeneity or focal lesions

T2-weighted images:

  • Thyroid tissue is moderately hyperintense compared to muscle

  • Cysts or fluid-containing nodules appear bright hyperintense

  • Useful for detecting inflammation, edema, or cystic degeneration

STIR (Short Tau Inversion Recovery):

  • Suppresses fat, accentuating inflammatory or edematous changes

  • Normal thyroid appears intermediate signal, while thyroiditis, tumors, or edema appear hyperintense

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal thyroid enhances intensely and homogeneously due to rich vascularity

  • Pathology: nodules, tumors, or thyroiditis may show heterogeneous or asymmetric enhancement

CT Appearance

Non-contrast CT:

  • Right lobe seen as a soft tissue density structure anterolateral to the trachea

  • Normal tissue homogeneous; calcifications may be present in nodules or carcinoma

Contrast-enhanced CT (CECT):

  • Thyroid enhances brightly and homogeneously in normal states

  • Helps differentiate benign vs malignant nodules, thyroiditis, goiter, and local invasion

  • Excellent for evaluating tracheal or esophageal compression, vascular encasement, or retrosternal extension

MRI images

Right lobe of thyroid gland coronal MRI image -img-00000-00000