Thyroid Gland Anatomy PDF

 Thyroid gland Shape: butter fly Extension:  Middle of thyroid cartilage “Oblique line” to 5th tracheal ring  5th cervical vertebra to 1st thoracic vertebra Movement: Gland move up / down with swallowing due to:  Levator glandul...

 Thyroid gland Shape: butter fly Extension:  Middle of thyroid cartilage “Oblique line” to 5th tracheal ring  5th cervical vertebra to 1st thoracic vertebra Movement: Gland move up / down with swallowing due to:  Levator glandulae thyrodie connect pyramidal lobe with hyoid bone  Pre-tracheal Fascia “false capsule” fix the gland to thyroid, cricoid cartilage Arterial l supply: 1. Thyroida ima artery: from arch of aorta to supply isthmus 2. Superior thyroid artery: o Origin External carotid artery o Associated nerve: External laryngeal nerve o Site of ligation: Close to the gland o Distribution: Upper 1/3 of lobe & Upper 1/2 of isthmus 3. Inferior thyroid artery: o Origin: thyro-cerival branch of 1st part of subclavian DR.Hendawy o Associated nerve: recurrent laryngeal nerve o Site of ligation: away from the gland o Distribution: lower 2/3 of lobe & lower 1/2 of isthmus & parathyroid gland DR.Hendawy “thyroid gland” Venous drainage: Superior & middle thyroid: drain into Internal jugular vein Inferior Thyroid: drain into brachiocephalic vein Lymph drainage: Upper part: drain into Upper deep Cervical LN Lower part: drain into Lower deep Cervical LN Isthmus: drain into Pre-tracheal LN Relation: Lobe: Lateral surface: related to 1. Sternomastoid 2. Sternohyoid 3. Superior Belly of omohyoid 4. Sternothyroid Medial surface: Upper part: related to Larynx, Pharynx& External Laryngeal nerve DR.Hendawy Lower part: related to Trachea, Esophagus& Recurrent laryngeal nerve Posterior surface: related to: Carotid sheath with its content  Anterior border: related to anterior branch of superior thyroid artery  Posterior border: related to parathyroid gland & anastomosis between superior, inferior thyroid arteries Isthmus: Anterior surface: related to Sterno-hyoid & Sterno- thyroid & anterior jugular vein Posterior surface: related to Tracheal ring “2,3,4” Superior border: related to Anastomosis between superior Thyroid arteries Inferior border: related to Anastomosis between inferior Thyroid arteries & Inferior thyroid vein & Thyroida ima artery DR.Hendawy “thyroid gland” Development:  Solid bilobed endodermal mass appears at foramen caecum of tongue  It descends anterior to hyoid bone then thyroid cartilage till it reaches its final position at 7th week  It becomes formed of isthmus & 2 lobes  It remain connected to tongue by thyro-glossal duct  Fate of thyro-glossal duct: 1. Proximal part: above hyoid bone degenerate 2. Distal part: forms pyramidal lobe & levator glandulae thyrodie  Para-follicular cells form 5th pharyngeal arch Anomalies:  Agenesis of thyroid  Agenesis of isthmus  Ectopic thyroid: lingual , sublingual, suprahyoid, subhyoid, retrosternal DR.Hendawy  The persistance of thyroglssal duct  Thyroglossal duct cyst  Thyroglossal fistula DR.Hendawy “thyroid gland”  Parathyroid gland Site: On posterior border of thyroid gland Arterial supply Inferior thyroid arteries Nerve supply: Superior & middle cervical sympathetic ganglion Development: DR.Hendawy  Superior parathyroid gland develop from 4th pharyngeal pouch  Inferior parathyroid gland develop from 3rd pharyngeal pouch DR.Hendawy “thyroid gland”