Thyroid Essay

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CH 14 THYROID GLAND Relations A. Relations of Lobes Anteriolaterally The infrahyoid group of muscles: − − − − Sternohyoid Superior belly of omohyoid Sternohyoid Anterior border of sternomastoid surgical Anatomy Anatomical Location Thyroid gland lies at the level of C5, C6, C7, and T1 vertebrae in the anterior triangle of the neck, covering the upper part of trachea. Parts of Gland − − Two lobes-right and left. A connecting isthmus (crosses the midline in front of 2nd, 3rd and 4th tracheal ring). A pyramidal lobe is often present, that projects upwards from isthmus. Posteriolaterally The carotid sheath and its contents: − − − Common carotid artery Internal jugular vein Vagus nerve − Extent − Each lobe extends from midline of thyroid cartilage to the 4th or 5th tracheal ring. Isthmus extends from 2nd to 3rd tracheal ring. Medially − − − − − − layrnx Trachea Esophagus Pharynx External laryngeal nerve Recurrent laryngeal nerve − Shape of Gland − − Whole gland → H-shaped. Each lobe → pear shaped with apex directing upwards. Posteriorlly The parathyroid glands. B. Relations Of Isthmus Anteriorlly − − − − − Skin Fascia Sternothyroid Sternohyoid Anterior jugular vein Weight of gland 20-25gms. Thyroid Capsules 1. True capsule: This is peripheral condensation of connective tissue of gland and a dense capillary plexus is present deep to it. 2. False capsule: It is derived from pretracheal layer of deep cervical fascia that encloses and suspends the thyroid gland. This is responsible for upwards movement of goiter on swallowing. Blood Supply Arteries − The superior thyroid artery (related to external laryngeal nerve) from external carotid artery. The inferior thyroid artery (related to recurrent laryngeal nerve) from thyrocervical trunk. Thyroid IMA artery (if present) from brachiocephalic trunk or aortic arch. Berry’s Ligament

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