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.