Give an account for the anatomy of the thyroid gland

Introduction: the thyroid gland is the largest endocrine gland
in the body. It is situated in the neck anterior to the trachea between the
levels of C5 and C7

Parts: it is made up of left and right lobes connected by
isthmus.

Relations:

Anteriorly: pretracheal fascia, strap muscle and sternocleidomastoid.
The anterior jugular vein courses over the isthmus.

Posteriorly: larynx and trachea, pharynx and esophagus and
the recurrent laryngeal nerve.

On left and right sides: the carotid sheath.

Arterial supply:

–         
Superior thyroid artery

–         
Inferior thyroid artery

–         
Thyroidea ima artery

Venous drainage:

–         
Superior thyroid vein

–         
Middle thyroid vein

–         
Inferior thyroid vein

Lymph drainage: the thyroid glands lymph drainage follows
the arteries:

1.      
From the upper poles: they enter the
anterosuperior group of deep cervical lymph nodes.

2.      
From the lower pole: lymph pass with inferior
thyroid artery into the posterior inferior group of deep cervical lymph nodes.

Nerve supply: nerve supply to the thyroid gland are derived
from the superior, middle and inferior cervical sympathetic ganglia.

Clinical correlates: enlargement of the thyroid may compress
or displace the trachea and esophagus resulting in their narrowing and
difficulty in breathing and swallowing.