thyroid gland , types of capsule, borders surfaces of thyroid gland, relation of thyroid gland, blood supply lymphatic drainage an nerve supply of thyroid gland, goiter, hyper and hypo thyroidism, thyroidectomy.

1. THYROID
Dr. SANA YASEEN
ANATOMY DEPARTMENT

2. • Endocrine gland
• Endodermal in origin
• Location: front of lower part of larynx and upper part of
trachea (anterior to the junction of the thyroid and cricoid
cartilages ).
• Weigh: 25gm

4. Extension

6. Parts
• Composed of
– 2 lobes joined together by isthmus.
• In some people, the gland has an additional lobe, called
the pyramidal lobe, that ascends from the left side of
the isthmus.
• The pyramidal lobe is an embryological remnant of the
path of descent of the thyroid primordium from its origin
in the forming tongue by way of the thyroglossal duct.
– 2 capsules (true and false)
• Each lobes are composed of :
– 3surfaces
– 2borders
– Apex
– Base

7. TRUE CAPSULE: is peripheral condensation of
connective tissue surrounding gland. Throwing into
septa and lobules.
FALSE CAPSULE: derived from pretracheal layer
of deep fascia.
• Moves during deglutition and speech.
• It is thick on inner surface of gland where it
forms suspensory ligament of berry, connects
lobe of thyroid to cricoid cartilage.

11. SURFACES
 Lateral:
 Is lateral and forward
 Covered by: skin, fascia, sternothyroid, sternohyoid,
omohyoid, sternocleidomastoid muscle
 Medial:
 Lies over thyroid & cricoid cartilage, trachea and
esophagus.
 Inferior constrictor of pharynx, recurrent laryngeal nerve
and external laryngeal nerve.
 Posterior:
• Carotid sheath and its contents

13. BORDERS
 Anterior:
 between lateral and medial surface.
Relation: branch of superior thyroid artery.
 Posterior:
 between posterior and medial surface
Relation: inferior thyroid artery
 Parathyroid gland
 Thoracic duct

14. • APEX: upper end extends up to oblique line of
thyroid cartilage
• Base: lower end extends up to 5-6 tracheal ring
or T1 vertebrae.

16. ISTHMUS
• lies in front of 2-4 tracheal ring
• Anteriorly related to: skin, fascia, sternohyoid,
sternothyroid muscles.
• Upper border: finger like projection (pyramidal
lobe) attach to hyoid bone by levator of thyroid
gland

18. ARTERIAL SUPPLY
• Superior thyroid artery: branch of ECA-
upper border of gland and isthmus
• Inferior thyroid artery: branch of
thyrocervical trunk- lower pole of gland

20. VENOUS DRAINAGE
• Superior thyroid
vein- IJV
• Middle thyroid vein
– IJV
• Inferior thyroid vein-
L-brachiocephalic
vein

22. FUNCTIONS OF THYROID GLAND
• Brain maturation
• Bone growth
• Beta adrenergic effects
• Increase rate of Basal metabolism
• Another hormone, calcitonin, aids in
decreasing blood calcium levels and
facilitates the storage of calcium in bones

23. • GOITER: is increase in the size of thyroid
gland.
• Hyperthyroidism:
• Hypothyroidism:

27. THYROIDECTOMY