Anatomical and Metabolic Description of Endocrine Glands

Anatomical and Metabolic Description of Endocrine Glands

Pituitary Gland:

• Intermediate lobe: This portion atrophies during embryonic development and no longer exists.

• Location: Resides in the hypophyseal fossa of the sphenoid bone.

• Shape: Resembles an apple.

Thyroid Gland:

• Color: Reddish brown.

• Size: In females, the thyroid gland is larger than in males, particularly during menstruation and pregnancy.

• Location: Located at the level of the 5th, 6th, and 7th cervical vertebrae, above the 2nd and 3rd tracheal rings, anterior to the cricoid and thyroid cartilage.

• Anterior relations: Skin, subcutaneous muscle, tracheal rings located immediately behind the isthmus of the thyroid gland.

• Medial relations: Cricoid cartilage, thyroid cartilage, cricothyroid muscle, inferior constrictor muscle of the pharynx.

• Anterolateral relations: Sternothyroid muscle, sternocleidomastoid muscle, omohyoid muscle, sternohyoid muscle.

• Posterolateral relations: Carotid sheath, external carotid artery, internal jugular vein.

• Mobility: The thyroid gland moves with swallowing due to the inferior constrictor muscle of the pharynx.

Blood Supply to the Thyroid Gland:

• Superior thyroid artery: Branches from the external carotid artery, divides into anterior and posterior branches, runs downward and laterally into the isthmus of the thyroid gland. The anterior branch connects with the opposite anterior branch, and the posterior branch connects with the branch of the inferior thyroid artery on the same side.

• Inferior thyroid artery: Branches from the thyrocervical trunk (branch of the subclavian artery), divides into two branches. One branch enters the lower posterior border of the thyroid lobe, the other enters the posterior internal part of the thyroid lobe. The two branches connect at the isthmus of the thyroid gland, with the recurrent laryngeal nerve running between them.

• Inferior thyroid artery: Branch of the thyrocervical trunk or aortic arch.

Venous Drainage from the Thyroid Gland:

• Superior thyroid vein: Travels along the superior thyroid artery and empties into the internal jugular vein.

• Middle thyroid vein: Runs along the lateral surface of the gland near the lower pole and drains externally into the internal jugular vein.

• Inferior thyroid vein: Descends anterior to the trachea and drains into the brachiocephalic veins.

Nerves of the Thyroid Gland:

• Only motor nerves: They do not regulate thyroid activity.

Parathyroid Glands:

• Location: These yellow, pea-sized glands are situated in the region below the lower poles of the thyroid lobes. The two superior parathyroid glands are located at the upper pole of the thyroid lobes, approximately 1.5 cm away.

• Blood supply: Inferior thyroid artery.

• Nerves: Nerves from the superior and middle cervical sympathetic ganglia.

Adrenal Glands:

• Location: Situated retroperitoneally.

• Right adrenal gland: Forms an impression on the liver, as a triangular area on the anterior surface of the liver, creating a suprarenal impression on the liver located near the inferior vena cava on the right lobe of the liver but not the part between the inferior vena cava and the ligamentum venosum.

• Left adrenal gland: The anterior surface – the superior surface presses against the cardiac stomach, separated by the lesser sac of the peritoneum.

Blood Supply to the Adrenal Glands:

• Superior adrenal artery: Branches from the inferior phrenic artery, divides into 6-8 branches that enter the adrenal gland forming a comb-like structure.

• Middle adrenal artery: Branches from the abdominal aorta, supplying blood to the upper and lower parts of the adrenal gland.

• Inferior adrenal artery: Branches from the renal artery.

Venous Drainage from the Adrenal Glands:

• Largest adrenal vein: The central vein originating from the hilum of the gland.

• Left: Empties into the inferior vena cava.

• Right: Empties into the renal vein.