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1. Thyroid Gland Anatomy - II
By:
Dr.Faris Muhammed Al-Haddad
PhD In Human Anatomy
Associate Professor In Human Anatomy
Medical College/ Hawler Medical University
February. 2022

2. • Arteries to the thyroid gland are:
1. Superior thyroid artery
2. Inferior thyroid artery
3. Thyroidea ima artery (sometimes)
• These arteries anastomose profusely
with one another over the surface of
the gland.
Blood Supply

3. 1. Superior thyroid artery,
• a branch of the external carotid artery,
• descends to the upper pole of each lobe,
• accompanied by the external laryngeal nerve

4. 2. Inferior thyroid artery (ITA)
• a branch of thyrocervical trunk,
• Ascends behind common carotid
artery & the gland to level of the
cricoid cartilage
• It then turns medially & downward
to reach the posterior border of
the gland.

5. • The recurrent laryngeal nerve (RLN) crosses ITA either:
• In front of the ITA
• Behind the ITA artery
• Pass between its branches.

6. 3. Thyroidea ima, (if present)
• either arises from the brachiocephalic a.
or arises from the arch of the aorta.
• It ascends in front of the trachea to
the isthmus

7. The veins from the thyroid gland
1. Superior thyroid v.: drains into (IJV)
2. Middle thyroid v.: drains into IJV
3. Inferior thyroid veins: of both sides
anastomose with one another as they
descend in front of the trachea. They drain
into the left brachiocephalic vein in the
thorax.

8. Lymphatic Drainagee

9. Nerve Supply

10. Relations of the Lobes

11. Anterolaterally:
• Skin
• Platysma
• Anterior jagular veins
• Investing layer of deep
cervical fascia
• Sternothyroid,
• Omohyoid (superior belly)
• Sternohyoid,
• Sternocleidomastoid
(anterior border)

12. Posterolaterally
• Carotid sheath:
1. Common carotid
artery
2. Internal jugular vein
3. Vagus nerve

13. Medially
1. Larynx / Trachea,
2. Pharynx / Esophagus.
3. Cricothyroid muscle
(and its nerve supply, the
external laryngeal nerve)
4. Recurrent laryngeal nerve
In the groove between the
esophagus and the trachea
5. Superior and inferior
parathyroid glands and
6. the anastomosis between the
superior and inferior thyroid arteries.

14. Relations of the Isthmus
• Anteriorly:
• The sternothyroids,
• sternohyoids,
• anterior jugular veins,
• fascia, and skin
• Posteriorly:
• 2nd, 3rd, and 4th rings of trachea
• The terminal branches of the superior
thyroid arteries anastomose along its
upper border.