Superior Thyroid Artery

Origin

• Arises at commencement of External Carotid Artery
  • 1st branch from the anterior aspect of the External Carotid Artery after giving off its Sternocleidomastoid and Superior Laryngeal branches

Course

• Pierces Pretracheal Fascia
• Runs almost vertically downwards, with the vein, to the upper pole of Thyroid
• Runs with the External Laryngeal Nerve
  • The Cernea Classification describes this relationship
• 4 branches prior to reaeching the upper pole
  • A single vessel reaches summit of upper pole
• Artery divides on the gland into anterior and posterior glandular branches
  • Anterior branch – runs down to Isthmus
  • Posterior branch – runs down the back of the lobe and anastomoses with an ascending branch of the Inferior Thyroid Artery from the lower pole
• In thyroidectomy – artery ligated close to upper pole or its anterior and posterior branches are ligated instead – avoid damage to External Laryngeal Nerve

Branches

• Before reaching Thyroid, it gives off
  • Infrahyoid branch
  • SCM brnach
  • Superior Laryngeal branch
    • Superior Laryngeal Artery pierces the Thyrohyoid Membrane with the Internal Laryngeal Nerve
  • Cricothyroid branch
    • Cricothyroid Artery crosses the upper part of the Cricothyroid membrane to anastomose with the contralateral artery