Dr Nimir Dr.Safaa

Objectives Discussing the anatomical structure of the thyroid gland in addition to the parathyroid glands. Recognizing the blood supply of the thyroid and parathyroid glands. Describing the nerve supply and lymphatic drainage of the thyroid and parathyroid glands. Describing the anatomical structure and relations of the suprarenal glands Recognizing the blood supply of the suprarenal glands.

The thyroid gland consists of right and left lobes connected by a narrow isthmus. Surrounded by a sheath derived from pretracheal fascia. The sheath attaches the gland to the larynx and the trachea. Lobe is pear shaped its apex reaches oblique line of thyroid cartilage. Its base lies below at the level of the fourth or fifth tracheal ring.

A pyramidal lobe often projects upward from the isthmus, usually to the left of the midline. A fibrous or muscular band frequently connects the pyramidal lobe to the hyoid bone, if it is muscular, it is referred to as the levator glandulae thyroideae.

Relations of the Lobes Anterolaterally: The sternothyroid, the superior belly of the omohyoid, the sternohyoid, and the anterior border of the sternocleidomastoid. Posterolaterally:Parathyroi d glands, the carotid sheath with the common carotid artery, the internal jugular vein, and the vagus nerve. Medially: The larynx, the trachea, the pharynx, and the esophagus.

Relations of the Isthmus Anteriorly: The sternothyroids, sternohyoids, anterior jugular veins, fascia, and skin Posteriorly: The second, third, and fourth rings of the trachea.

Blood Supply: The arteries are the superior thyroid artery, the inferior thyroid artery, and sometimes the thyroidea ima. superior thyroid artery, a branch of the external carotid artery, and the inferior thyroid artery, a branch of the thyrocervical trunk, and sometimes by the thyroid ima artery, branching directly from the subclavian artery. The veins are the superior thyroid, which drains into the internal jugular vein; the middle thyroid, which drains into the internal jugular vein; and the inferior thyroid drain into the left brachiocephalic vein.

Lymph Drainage: The lymph from the thyroid gland drains mainly laterally into the deep cervical lymph nodes. A few lymph vessels descend to the paratracheal nodes. Nerve Supply Superior, middle, and inferior cervical sympathetic ganglia.

The parathyroid glands are ovoid bodies about 6 mm long. They are four in number and are closely related to the posterior border of the thyroid gland, lying within its fascial capsule.

Blood Supply: The arterial supply to the parathyroid glands is from the superior and inferior thyroid arteries. The venous drainage is into the superior, middle, and inferior thyroid veins. Lymph Drainage: Deep cervical and paratracheal lymph nodes Nerve Supply Superior or middle cervical sympathetic ganglia.

Suprarenal Glands: The two suprarenal glands are yellowish retroperitoneal organs that lie on the upper poles of the kidneys. They are surrounded by renal fascia (but are separated from the kidneys by the perirenal fat). Each gland has a yellow cortex and a dark brown medulla.

The right suprarenal gland is pyramid shaped on the upper pole of the right kidney. It lies behind the right lobe of the liver and extends medially behind the inferior vena cava. It rests posteriorly on the diaphragm. The left suprarenal gland is crescentic in shape and extends along the medial border of the left kidney from the upper pole to the hilus. It lies behind the pancreas, the lesser sac, and the stomach and rests posteriorly on the diaphragm

Blood Supply: superior suprarenal artery (from inferior phrenic artery) middle suprarenal artery (from abdominal aorta) inferior suprarenal artery (from renal artery) venous drainage suprarenal veins drain emerge from the hilum and drain to left renal vein (left adrenal gland) IVC (right adrenal gland) Lymph Drainage: The lymph drains into the lateral aortic nodes.

Nerve Supply: Preganglionic sympathetic fibers derived from the splanchnic nerves supply the glands. Most of the nerves end in the medulla of the gland.