Thyroid Diseases

2 Thyroid Diseases



Thyroid and Parathyroid Anatomy



image

Thyroid Gland and Pharynx: Posterior View



Thyroid



• Thyroid typically consists of right and left lobes, connected by a midline isthmus, with an ascending pyramidal lobe in about 50% of cases.

• Location
image Immediately anterior and lateral to trachea, from about 5th cervical vertebra to 1st thoracic vertebra

image Medial to internal jugular veins

image Anterior to common carotid arteries

image Deep to infrahyoid muscles: sternohyoid (medial), omohyoid, sternothyroid (lateral)

image Infrahyoid muscles embedded in pretracheal fascia, deep to investing fascia of neck (superficial layer of deep fascia)

• Connective tissue (true) capsule is continuous with the septa dividing the stroma of the gland.

• Surgical (false) capsule lies external to the true capsule and is derived from the pretracheal fascia.

• Of the overlying strap muscles, the sternohyoid is most superficial, overlying the sternothyroid and thyrohyoid.

• Thyroid follicular (epithelial/principal) cells secrete thyroxine (T4) and triiodothyronine (T3), regulated by TSH receptors.

• Thyrotropin-releasing factor or hormone (TRF or TRH) from hypothalamus controls TSH release from pituitary.

• Parafollicular (C) cells secrete calcitonin.


Parathyroids



• Superior parathyroid glands usually lie between the true capsule of the thyroid and its investing surgical (false) capsule fascia.

• Inferior parathyroid glands might lie between the true and false capsules, within the thyroid parenchyma, or on the outer surface of the surgical capsule.


Vessels and Lymphatics



image

Blood Vessels and Parathyroid Glands

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Aug 12, 2016 | Posted by in ANATOMY | Comments Off on Thyroid Diseases

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