A,L5 Parathyroid and suprarenal glands .pptx

Parathyroid and suprarenal glands

1. The Parathyroid Glands Dr. Rehab Siddig Mohammed

2. Parathyroid glands Four small, nodular parathyroid glands are embedded in the posterior surface of the thyroid gland.

3. Parathyroid glands Each gland measures 6 × 3 × 2 mm Inside the fascial capsule of the thyroid gland. The secretion of parathyroid glands is called parathyroid hormone or parathormone . It maintains the blood calcium level by mobilizing the stored calcium from the bones.

4. Parathyroid glands The superior parathyroid gland of each side is usually on a level with the junction of upper and middle-thirds of lateral lobe of thyroid gland. The inferior gland lies near the angle between the inferior thyroid artery and recurrent laryngeal nerve.

5. The parathyroid glands Appear as small yellowish brown bodies. They are identified during surgery by isolating a small arterial branch that runs from the inferior thyroid artery to each parathyroid gland.

6. Blood Supply Both upper and lower parathyroids are usually supplied by the inferior thyroid artery, otherwise by an anastomosis between the superior and inferior arteries. Their minute veins join thyroid veins.

7. Nerve supply Sympathetic vasoconstrictor fibres enter with the arteries.

8. Parathyroid gland The superior gland is termed parathyroid IV because it develops from the fourth pharyngeal pouch. The inferior gland is parathyroid III , developed from the third pouch.

9. Development The superior parathyroid glands develop from the endoderm of the fourth pharyngeal pouch on each side. The inferior parathyroid glands develop along with thymus from the endoderm of third pharyngeal pouch. Both descend to reach their definitive positions. At times the inferior parathyroid may descend in superior mediastinum.

10. DiGeorge Syndrome Infants are born without a thymus and parathyroid glands and have defects in their cardiac outflow tracts. In some cases, ectopic glandular tissue has been found. Patients with complete DiGeorge anomaly have immunological deficiencies, hypocalcemia , and a poor prognosis.

11. DiGeorge anomaly Craniofacial defects Orbital hypertelorism Microstomia .

12. Nezelof’s syndrome Thymus and inferior parathyroid glands are absent but superior parathyroid glands are present.

13. Ectopic Parathyroid Glands The location of the parathyroid glands is highly variable. They may be found anywhere near or within the thyroid gland or thymus. The superior glands are more constant in position than the inferior ones. Occasionally, an inferior parathyroid gland remains near the bifurcation of the common carotid artery. In other cases, it may be in the thorax.

14. Abnormal Number of Parathyroid Glands Uncommonly there are more than four parathyroid glands. Supernumerary parathyroid glands probably result from division of the primordia of the original glands. Absence of a parathyroid gland results from failure of one of the primordia to differentiate or from atrophy of a gland early in development.

15. Surgical approach For parathyroidectomy the lobes of the thyroid gland are exposed as for thyroidectomy , and then retracted forwards and medially so that the posterior surfaces can be inspected for the parathyroids . If not obvious, branches of the inferior thyroid artery are followed and should lead to the glands. Exposure of the thymus through a median sternotomy may be necessary.

16. Parathyroidectomy Usually, three and half glands are removed leaving one half in the normal position. Alternatively, all the four glands are removed and a few pieces of one gland are implanted in the muscle of the forearm on one side, where they grow and produce required hormone.

17. Parathyroid The endocrine cells of the parathyroid are arranged in cords There are two types of cells: Chief cells Secrete PTH which Regulate Calcium and phosphorus levels Oxyphil cells

18. Any Questions ?

19. The Suprarenal Glands Dr. Rehab Siddig Mohammed

20. Suprarenal Glands Parts Weight & Shape Relations Histology Arterial Supply Venous Drainage Lymph Nerve Supply Development Anomalies

21. Renal fascia The suprarenal gland and kidney are enclosed in a common fascial sheath called the renal fascia They occupy separate compartments inside the fascial sheath.

22. Parts The suprarenal gland is composed of an outer cortex and an inner medulla, Developmentally, structurally and functionally are distinct from each other. The cortex and medulla are regarded as two separate endocrine glands.

23. Weight & Shape Each gland weighs about 4 to 5 g Each gland measures 50×30×10 mm. The right gland is an irregular tetrahedron. The left gland is of semilunar shape.

24. Relations

25. blood Supply Each adrenal gland is supplied with blood by the superior , middle , and inferior suprarenal arteries and drained by the suprarenal veins parathyroid parathyroid

26. blood Supply The vessels form a system that consists of Capsular capillaries that supply the capsule. Fenestrated cortical sinusoidal capillaries that supply the cortex and then drain into the fenestrated medullary capillary sinusoids. Medullary arterioles that traverse the cortex, traveling within the trabeculae , and bring arterial blood to the medullary capillary sinusoids .

27. blood Supply The venules that arise from the cortical and medullary sinusoids drain into the small adrenomedullary collecting veins that join to form the large central adrenomedullary vein . The central adrenomedullary vein drains directly as the suprarenal vein into the inferior vena cava on the right side and into the left renal vein on the left side.

28. blood Supply In humans, the central adrenomedullary vein and its tributaries have a tunica media containing bundles of smooth muscle cells . Synchronous contraction of longitudinal smooth muscle bundles cause the volume of the adrenal gland to decrease.

29. Lymphatic vessels Are present in the capsule and the connective tissue around the larger blood vessels in the gland.

30. Nerve Supply The postganglionic sympathetic innervation to cortex and medulla is vasomotor in function. The cortex is regulated by ACTH. The medulla is regulated by preganglionic sympathetic fibers from the greater and lesser splanchnic nerves via the suprarenal plexus. They make synaptic contacts with each and every chromaffin cell of the medulla.

31. Development of Adrenal Glands Early in the second month of embryonic development of the adrenal gland begin to develop. The adrenal cortex is derived from intermediate mesoderm located in a region called the urogenital ridge.

32. Development of Adrenal Glands The adrenal medulla develops from neural crest cells that migrated from the developing neural tube . Maturation and development of the adrenal gland continue into early childhood.

33. Anomalies of Suprarenal Gland Accessory suprarenal tissue may be found: around the main gland, in greater omentum , in broad ligament of uterus.

34. Adrenocongenital syndrome The hyperplasia of cortex leads to excess production of androgens In the female fetus the external genitalia resemble that of male ( pseudohermaphroditism ). In the male fetus, leads to a very early development of secondary sexual characters.

35. Anomalies of Suprarenal Gland If the developing kidney fails to ascend to the lumbar region, the suprarenal gland develops in its normal position.

36. Adrenal Gland Functionally divided Cortex Subdivide into: zona glomerulosa zona fasciculata zona reticularis Develop from mesoderm Medulla Develop from ectoderm ( neural crest)

37. Zona Glomerulosa cells are arranged in arched cords surrounded by capillaries Secrete mineralocorticoids: Aldosterone stimulating the reabsorption of sodium.

38. Zona Fasciculata arrangement of the cells in thick straight cords have capillaries between them cells rich in lipid Secrete glucocorticoids : Cortisol affect the metabolism of carbohydrates

39. Zona Reticularis Small cells It contains cells disposed in irregular cords that form an anastomosing network. Secretes androgen

40. Regulation Cortex : pituitary (ACTH) Medulla : sympathetic nervous system

41. Medulla cells arranged in cords and supported by a reticular fiber network. profuse capillary few presympathetic ganglion cells. secrete epinephrine and norepinephrine

42. الحمدُ للهِ ربِّ العَالمَينِ 10:02 PM