anatomy of glands

1. SUPRA RENAL
GLANDS
Supra renal glands or adrenal glands are a pair of glands situated retroperitoneally on
the upper pole of the corresponding kidney.

2. Suprarenal
glands

3. CAPSULES
◦ Inner true capsule and outer false capsule
◦ Inner true capsule is derived from the condensation of the fibrous stroma of the gland.
◦ Outer false capsule is derived from renal fascia. Renal fascia splits into two layers at the
upper pole of each kidney, covers the supra-renal gland. At the upper pole of each
supra-renal gland, the two layers of renal fascia reunite and then reflect towards the
diaphragm as the suspensory ligament of supra-renal gland.

4. Capsule

5. SHAPE
◦ Right gland is pyramidal
◦ Left gland is semilunar in shape

7. RIGHT SUPRA-RENAL GLAND
◦ It presents- base, apex, anterior and posterior surfaces, lateral and medial borders.
◦ Base is directed below and overlaps the upper end of right kidney.
◦ Apex is directed above and presents a hilum for right supra-renal vein.
◦ Anterior surface is related to Liver, IVC and superior duodenal flexure.
◦ Posterior surface is related to diaphragm and right kidney.

8. LEFT SUPRA-RENAL GLAND
◦ The gland presents- lower and upper ends, anterior and posterior surfaces, lateral and
medial borders.
◦ Lower end presents the hilum for left supra-renal vein.
◦ Upper end is related to spleen.
◦ Anterior surface is related to stomach, pancreas and splenic artery.
◦ Posterior surface is related to diaphragm and left kidney.

9. Relations

10. STRUCTURE
◦ Each gland consists of outer cortex and inner medulla.
◦ The cells of the cortex are arranged in three zones named from outside inwards- zona
glomerulosa, zona fasciculata and zona reticularis.
◦ Zona glomerulosa consists of small polyhedral cells which have basophilic cytoplasm
and deeply stained nuclei. Cells are arranged in arches or irregular clusters. Thiszone
liberates mineralocorticoids which regulate sodium and potassium balance of the
body. The principal mineralocorticoid is aldosterone.
◦ Zona fasciculata is thickest of the three zones and consists of polyhedral cells with
basophilic cytoplasm, abundant mitochondria and smooth endoplasmic reticulum.
Cells are arranged in straight cords. Zona fasciculata releases glucocorticoids which
regulate protein and carbohydrate metabolism of the body. Cortisol is the most active
glucocorticoid.

11. STRUCTURE
◦ Zona reticularis consists of irregularly arranged cell clusters. Cells are polyhedral and
contain basophilic cytoplasm. Zona reticularis mainly secrete sexcorticoids- androgen
and estrogen which regulate the secondary sexual characteristics.
◦ Zona fasciculata also secretes sex-corticoids.
◦ Zona reticularis also releases glucocorticoids.
◦ Medulla consists of chromaffin cells and ganglion cells. Chromaffin cells are tall
columnar cells with basophilic cytoplasm and membrane bound granules. They
secrete epinephrine and nor-epinephrine.

12. Structure

13. ARTERIAL SUPPLY
◦ Superior supra-renal artery ( branch of inferior phrenic artery)
◦ Middle supra-renal artery (branch of abdominal aorta)
◦ Inferior supra-renal artery (branch of renal artery)

14. VENOUS DRAINAGE
◦ Right supra renal vein drains into IVC.
◦ Left supra-renal vein drains into left renal vein.

15. Arterial
supply

16. Venous
drainage

17. APPLIED ANATOMY
◦ Deficiency of mineralocorticoids- Addison's disease
◦ Adrenal hyperplasia-
◦ Conn's syndrome (excessive mineralocorticoids)
◦ Cushing's syndrome (excessive glucocorticoids)
◦ Adrenogenital syndrome ( excessive sex-corticoids)
◦ Pheochromocytoma is a tumor of medulla.

18. PANCREAS
Pancreas is a soft lobulated gland consisting of both exocrine and endocrine parts.

19. Pancreas

21. PRESENTING PARTS
◦ It occupies posterior part of the epigastrium and left hypochondrium.
◦ From right to left the pancreas presents head, neck, body and tail.
◦ Head is contained within curve of duodenum.
◦ Neck lies in front of portal vein.
◦ Body extends from the front of the aorta to the front of left kidney. It is triangular on
cross-section.
◦ Tail is present between two layers of leino-renal ligament and reaches the spleen.

22. Head and
Neck of
Pancreas
◦ Anterior view

23. Head and
neck of
Pancreas
◦ Posterior view

24. HEAD
◦ Head is contained within C shaped curve of the duodenum.
◦ Vertebral level- L1, L2
◦ Two surface- anterior and posterior
◦ Four borders- upper, lower, right and left
◦ One process- uncinate process
◦ Anterior relations- transverse colon, few coils of jejunum, superior
mesentricartery
◦ Posterior relations: IVC, both renal veins, bile duct, right crus of the
diaphragm

25. HEAD
◦ Upper border is related firstpart of duodenum.
◦ Right border is related to second part of duodenum.
◦ Lower border is related to third part of duodenum.
◦ Left border is related to fourth part of duodenum.
◦ In the groove between pancreas and duodenum lies the anastomoses between
superior and inferior pancreatico-duodenal vessels.

26. NECK
◦ Two surface- Anterior and posterior
◦ Two borders- upper and lower
◦ Anterior relation: pyloric end of the stomach
◦ Posterior relation: superior mesenteric vein and trunk of portal vein
◦ Upper border is related to first part of duodenum.
◦ Lower border gives attachment to transverse mesocolon.

27. Body of the
Pancreas

28. Body and
tail of the
pancreas
◦ Anterior view

29. BODY
◦ Three surface: anterior, posterior and inferior
◦ Three borders- superior, inferior and anterior
◦ Anterior relation: Stomach
◦ Inferior relation: duodeno-jejunal flexure, left colic flexure, few coils
of jejunum.
◦ Posterior relation: abdominal aorta, superior mesenteric artery,
splenic vein, left kidney, left supra renal gland, pelvis of left ureter
◦ Superior border presents an elevation known as tuber omentale.
◦ Anterior border gives attachment to transverse mesocolon.

30. TAIL
◦ Tail reaches the spleen in between two layers of leino-renal ligament.
◦ It is the most mobile part of spleen.
◦ Lies opposite T12.
◦ Comes in relation with spleen and splenic vessels, stomach and left colic flexure.

31. Pancreatic
ducts

32. PANCREATIC DUCTS
◦ Main pancreatic duct/ Duct of Wirsung:
◦ It begins in the tail by union of a number of smaller pancreatic ducts and passes from left to
right through the midway between upper and lower margins and close to the posterior surface.
The main duct receives a number of smaller ducts resembling Herring Bone Pattern. The duct
passes downwards and backwards at the neck and pierces the postero-medial wall of 2nd part
of duodenum and unite with the bile duct to form ampulla of Vater. This ampulla opens at the
summit of major duodenal papilla.
◦ Accessory pancreatic duct/ Duct of Santorini:
◦ It receives the secretion of uncinate process. The duct passes upwards and to the right,
communicates with the main pancreatic duct and finally opens at the summit of minor
duodenal papilla.

33. Pancreatic
ducts

34. STRUCTURE
◦ The exocrine part of the pancreas consists of numerous lobules separated by
interlobular septa.
◦ Each lobule consists of numerous alveoli and terminal most branches of the main duct.
The alveolar wall is lined by single layer of columnar cells.
◦ Each alveolar cell presents a basophilic basal zone and an eosinophilic apical zone.
The basal zone contains RER for protein synthesis. The apical region contain zymogen
granules and store digestive enzymes.
◦ Each alveolus is connected to the main pancreatic duct by a succession of intercalary
ducts, intralobular ducts and interlobular ducts.

35. STRUCTURE
◦ The duct cell epithelium consist of flattened epithelial cells. The junction between
alveoli and ductules is lined by Centro-acinar cells.These cells act as a progenitor cell
for different types of pancreatic cells.
◦ The duct cells and Centro-acinar cells contain carbonic anhydrase.
◦ There is another important cell known as pancreatic stellate cell which plays an
important role in different pathology of pancreas.
◦ The exocrine pancreas releases pancreatic proteases, pancreatic lipase, pancreatic
amylase and many other enzymes. The exocrine pancreas also secretes bicarbonate.

36. STRUCTURE
◦ The endocrine part of the pancreas consists of numerous islets of Langerhans which are
dispersed throughout the entire organ as isolated cellular masses. They are more
numerous in the tail.
◦ Each islet is a collection of polyhedral cells and permeated by capillaries.
◦ Four major types of cells are found in islets. They are alpha cells (glucagon), beta
cells(insulin), delta cells (somatostatin) and PP cells (pancreatic polypeptide).
◦ Alpha cells secrete glucagon.
◦ Beta cells secrete insulin.
◦ Delta cell secrete somatostatin which inhibits release of both insulin and glucagon.
◦ PP cells secrete pancreatic polypeptide hormone which stimulates the secretion of
gastric and intestinal enzymes and inhibits intestinal motility.
◦ There are also cells that secrete VIP, serotonin.

37. Arterial
supply

38. Venous
drainage

39. BLOOD SUPPLY
◦ Head and neck of the pancreas are supplied by the anastomoses of superior and
inferior pancreatico-duodenal arteries.
◦ Body and tail are supplied by the pancreatic branches of splenic arteries.
◦ Veins correspond to the arteries and drain into superior mesenteric and splenic vein;
ultimately into portal vein.

40. THYMUS
Thymus is a primary lymphoid organ. Within the thymus T cells mature.

41. Thymus

42. STRUCTURE
◦ The thymus has two lobes and is situated in the anterior superior mediastinum, in front of
the heart and on either side of the trachea.
◦ At birth thymus weighs 10-15gm. It progressively increases in size up to the age of
puberty when it weighs about 20-30 gm. Thereafter the thymus undergoes involution
and is converted into fibro-fatty mass. In mid adult life it weighs about 10 gm.
◦ Each thymic lobe is covered by a fibrous capsule which projects in the substance of
the organ as trabecular septa. The trabecular septa convey the blood vessels and
divide the thymus into numerous lobules.
◦ Each lobule consists of outer cortex and inner medulla.

43. STRUCTURE
◦ The cortex is primarily composed of aggregated lymphocytes and occasional
macrophage cells. Such cells are supported by a network of finely branched epithelial
reticular cells.
◦ In the medulla the lymphocytes are less in number and there are concentric nest like
bodies called Hassall’s corpuscles. The network of epithelial reticular cells is continuous
with that of cortex.
◦ The epithelial reticular framework also contains macrophages, plasma cells and mast
cells. This network forms a haemo-thymic barrier.
◦ The cortex is the place for earlier events in thymocyte development whereas the
medulla is the place for later stages of thymocyte development.
◦ Thymocytes are hematopoietic progenitor cells present in the thymus. Thymocytes
differentiate into mature T lymphocytes.

44. Histology

45. STRUCTURE
◦ More than 90% of the thymic lymphocytes are shortlived with a span of 3-4 days. About
5% of the surviving lymphocytes appear in the circulating pool, and thereby appear in
primary lymphatic folliclesand peripheral organs of lymphatic system.
◦ The arteries supplying the thymus are internal thoracic, inferior thyroid and superior
thyroid arteries.
◦ The veins end in left brachio-cephalic vein, internal thoracic vein and in inferior thyroid
veins.
◦ Lymphatic vessels from thymus drain into brachiocephalic, tracheobronchial and
parasternal lymph nodes.