The thyroid gland is a butterfly-shaped endocrine organ located in the front of the neck. It secretes thyroid hormones that help regulate metabolism. During development, it begins as an outgrowth in the pharynx that migrates down the neck. Congenital anomalies can occur if the gland fails to descend fully or develops ectopically. The thyroid is supplied by superior, inferior, and thyroid iodine arteries and drains into internal jugular veins. Diseases like goiter, hyperthyroidism, and hypothyroidism may affect the thyroid and surrounding structures.

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Contents…
✓ Thyroid Gland
✓ Development of the Thyroid Gland
✓ Congenital anomalies of thyroid gland
✓ clinical Notes
PRESENTED BY - GURJAR GANESH KUMAR

2. Glands of Head & Neck
Thyroid Gland
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3. ● The thyroid gland is a highly vascular endocrine organ which
secretes the thyroid hormone.
Shape:
● roughly H-shaped
Parts
● 2 lobes: Rt & Lt
● isthmus, which connects the lobes
● sometimes a pyramidal lobe is present
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Thyroid gland

4. Position:
● It is situated in front and at the sides of trachea opposite to the level
of CV5, 6, 7 & T1
● each lobe extends from the middle of thyroid cartilage to 4th or 5th
tracheal ring
● isthmus extends from 2nd to 3rd tracheal ring
Dimension & weight:
● Lobe – 5 X 2.5 X 2.5 cm / Isthmus – 1.2 X 1.2 cm
● Avg. weight – 25 g
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Thyroid gland contd…

5. Dr.HSMMali
Relations
Anterolat
● sternothyroid
● sternohyoid
● sup belly of
omohyoid
● ant border of
sternocleido-
mastoid
Posterolat
carotid sheath & its
contents:
● 1. CCA
● 2. IJV
● 3. vagus n
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6. Dr.HSMMali
Relations
Medially
● larynx
● trachea
● inf constrictor of
pharynx
● esophagus
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7. Arterial Supply:
● Superior thyroid artery - from External carotid
artery
● Inferior thyroid artery - from thyrocervical trunk
● Arteria thyroidea inferior Mesenteric artery -
from brachiocephalic artery / arch of aorta
Venous Drainage:
● Superior thyroid vein - into Internal jugular vein
● middle thyroid vein - into Internal jugular vein
● Inferior thyroid vein – into brachiocephalic vein
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10. Development of the Thyroid Gland
● The thyroid gland begins to develop during the third
week as an entodermal thickening in the midline of
the floor of the pharynx between the tuberculum impar
and the copula.
● Later, this thickening becomes a diverticulum that grows
inferiorly into the underlying mesenchyme and is called
the thyroglossal duct.
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11. Development of the Thyroid Gland contd…
● As development continues, the duct elongates, and its distal end
becomes bilobed.
● Soon, the duct becomes a solid cord of cells, and as a result of
epithelial proliferation, the bilobed terminal swellings expand to form
the thyroid gland.
● The thyroid gland now migrates inferiorly in the neck.
● By the seventh week, it reaches its final position in relation to the
larynx and trachea.

12. Developmental sources of thyroid
● Follicular cells: Develop from the median endodermal
thyroid diverticulum in the primitive pharynx.
● Parafollicular cells: Develop from ultimobranchial body,
which is derivative of pharyngeal pouch.
● Fibrous capsule and connective tissue: From
surrounding mesoderm.
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13. Congenital anomalies of thyroid gland
1. Agenesis of the thyroid
2. Incomplete descent of the thyroid, eg, Lingual thyroid.
3. Ectopic thyroid tissue
4. Persistent thyroglossal duct
5. Thyroglossal cyst
6. Thyroglossal fistula.
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14. Ectopic thyroid
● When the thyroid gland lies other than its normal
position and along its roots of descent, it is known
as ectopic thyroid, e.g. lingual thyroid, retrosternal
thyroid etc.
● Ectopic thyroid tissue is occasionally found in the
thorax in relation to the trachea or bronchi or even
the esophagus.
● It is assumed that this thyroid tissue arises from
entodermal cells displaced during the formation of
the laryngotracheal tube or from entodermal cells of
the developing esophagus.
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15. ● goitre = any enlargement of thyroid gland
➢ Causes: eg, iodine def, puberty (puberty goitre), tumours, etc
● hyperthyroidism
● hypothyroidism
● because of the relations of the thyroid to impt structures,
thyroidectomy may cause damage to the structures
● enlargement of the gland may displace & compress the
structures, eg, trachea
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clinical Notes

16. Dr.HSMMali
REFERENCES
● B. D. Chaurasiya
● Grays anatomy
● Google
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17. The End
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