Thyroid gland anatomy

Surfaces of gland and isthmus

Gland: lateral medial and posterior Isthmus: anterior and posterior

Relations to medial surface

Inferior constrictor and cricothyroid Trachea and oesophagus External and recurrent laryngeal nervez

Arterial blood supply

Inferior thyroid artery supplies blood to major part of thyroid Gland and anastomoses with descending branch of superior thyroid artery

Relations to posterior surface

Carotid sheath

Situation

Situated in front of c5 c6 c7 and r1 vertebrae

Venous drainage

Superior thyroid vein and middle thyroid vein drain into jnternal jugular vein Inferior thyroid vein into the brachiocephalic vein

Capsules

True capsules and false capsules

Relations to borders

Anterior: superior thyroid artery Posterior: parathyroid 1. Inferior thyroid artery 2. Thoracic duct 3. Anastomosis between superior and inferior thyroid artery

Dimention and weight

Each lobe measures: 5x2.5x2.5 cm Isthmus: 1.2x1.2 cm Weight 25gm

Relations to lateral surface

Sternohyoid Sternothyroid Superior belly of omohyoid Sternomastoid