Superior thyroid artery

Artery: Superior thyroid artery
Superficial dissection of the left side of the neck, showing the carotid and subclavian arteries.
The fascia and middle thyroid veins. (Superior thyroid artery labeled at upper right.)
Latin	arteria thyreoidea superior
Gray's	subject #144 552
Supplies	thyroid
Source	external carotid artery
Branches	Hyoid (infrahyoid) artery Sternocleidomastoid artery Superior laryngeal artery Cricothyroid artery
Vein	superior thyroid vein

The superior thyroid artery arises from the external carotid artery just below the level of the greater cornu of the hyoid bone and ends in the thyroid gland.

Relations

From its origin under the anterior border of the Sternocleidomastoideus it runs upward and forward for a short distance in the carotid triangle, where it is covered by the skin, Platysma, and fascia; it then arches downward beneath the Omohyoideus, Sternohyoideus, and Sternothyreoideus.

To its medial side are the Constrictor pharyngis inferior and the external branch of the superior laryngeal nerve.

Branches

It distributes twigs to the adjacent muscles, and numerous branches to the thyroid gland, anastomosing with its fellow of the opposite side, and with the inferior thyroid arteries.

The branches to the gland are generally two in number;

Besides the arteries distributed to the muscles and to the thyroid gland, the branches of the superior thyroid are:

• Hyoid (infrahyoid) artery
• Sternocleidomastoid artery
• Superior laryngeal artery
• Cricothyroid artery

Surgery

This artery must be ligated at the thyroid when conducting a thyroidectomy. If the artery is severed, but not ligated, it will bleed profusely. In order to gain control of the bleeding the surgeon may need to extend the original incision laterally to gain access to its origin from the external carotid artery and ligate it there.

A surgeon tells a medical student to tap the side of the face of a patient who just had thyroid surgery. The surgeon is most worried about damage to which of the following vessels? Answer: Superior and inferior thyroid arteries. Why? These vessels also supply the parathyroid glands. If disrupted during surgery, necrosis of the parathyroids occurs, with subsequent hypocalcaemia and tetany. The masseter is a good muscle to test for tetany.

See also

• Inferior thyroid artery

Additional images

• 

  Diagram showing the origins of the main branches of the carotid arteries.

• 

  The internal carotid and vertebral arteries. Right side. (Superior thyroid visible at center.)

• 

  The thyroid gland and its relations.

• 

  Side of neck, showing chief surface markings.

External links

• SUNY Figs 26:02-02
• Superior+thyroid+artery at eMedicine Dictionary
• lesson5 at The Anatomy Lesson by Wesley Norman (Georgetown University) (antthyroidgland)

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.