Anatomy of the adrenal gland

Question 1

What is the adrenal (suprarenal) gland?

Answer 1

• A yellowish retro-peritoneal organ, that lies on the superomedial part of each kidney
• The right one is triangular/pyramidal
• The left one is semilunar in shape
• They are not covered by the peritoneum, instead surrounded by connective tissue and embedded in perirenal fat

Question 2

What is the vertebral relation of the adrenal gland?

Answer 2

T11

Question 2

What separates the adrenal gland from the kidneys?

Answer 2

The perinephric fat

Question 3

What encloses the adrenal gland?

Answer 3

The RENAL FASCIA (true capsule) is formed by the connective tissue around the kidneys

• A common fascial sheath that encloses the kidney and the adrenal gland
• It covers the whole kidney even the portion underneath the adrenal gland

Question 4

What attaches the adrenal gland to the (crura) of the diaphragm above?

Answer 4

The RENAL FASCIA

Question 5

What are the relations of the renal fascia?

Answer 5

It splits and encloses the kidney after that it splits and encloses the suprarenal glands, and after that, it fixes itself to the inferior surface of the diaphragm.

Question 6

What are the different types of fat around the kidneys and adrenals?

Answer 6

1) Perirenal fat: Around the kidney, protects it inside the renal fascia

2) Pararenal fat: a thick layer of fat located more posteriorly outside the renal fascia

Question 7

What will happen if someone loses weight suddenly?

Answer 7

The kidney will go down, but the adrenals will stay up due to their attachment to the crura of the diaphragm

Question 8

What is the anterior relation of the right (triangular) adrenal gland?

Answer 8

1) Liver

2) IVC

Question 9

What is the medial relation of the triangular adrenal gland?

Answer 9

IVC

Question 10

What is the posterior relation of the right (triangular) adrenal gland?

Answer 10

Diaphragm

Question 11

What is the anterior “superior” relation of the left (semilunar) adrenal gland?

Answer 11

Stomach

Question 12

What is the anterior “inferior” relation of the left (semilunar) adrenal gland?

Answer 12

1) Pancreas

2) Splenic vessels

Question 13

What is the Posterior relation of the left (semilunar) adrenal gland?

Answer 13

Diaphragm

Question 14

What is the Medial relation of the left (semilunar) adrenal gland?

Answer 14

Abdominal aorta

Question 15

What are the parts of the adrenal glands?

Answer 15

1) Outer cortex (80-90%)

2) Inner medulla (10-20%)

Question 16

What is the embryological origin of the outer cortex?

Answer 16

Mesodermal origin

Question 17

What is the embryological origin of the inner medulla?

Answer 17

Neuroectodermal (neural crest, which also gives rise to the sympathetic and parasympathetic ganglia)

• They are considered to be modified sympathetic and postganglionic, who have lost their axons and dendrites during development and became secretory cells

Question 18

Summary

Answer 18

The adrenal glands consist of an outer connective tissue capsule, a cortex and a medulla. Veins and lymphatics leave each gland via the hilum, but arteries and nerves enter the glands at numerous sites.
The outer cortex and inner medulla are the functional portions of the gland. They are two separate endocrine glands, with different embryological origins:
Cortex – derived from the embryonic mesoderm.
Medulla – derived from the ectodermal neural crest cells.
The cortex and medulla synthesise different hormones.

Question 19

Describe the arterial blood supply of the adrenal gland

Answer 19

1) Superior: Inferior phrenic artery

2) Middle: Aorta

3) Inferior: Renal artery

Question 20

What is the venous supply of the right (triangular) adrenal gland?

Answer 20

The right suprarenal vein, which drains into the inferior vena cava

Question 21

What is the venous supply of the left (semilunar) adrenal gland?

Answer 21

The left suprarenal vein, drains into the renal vein then the renal vein will drains into the inferior vena cava

Question 22

Why should we ligate the right adrenal gland vein first in surgery?

Answer 22

The right suprarenal vein is very short so it can be easily cut off in surgery by mistake. That’s why you need to take care of it and ligate it first

• Not ligating the vessels before an adrenal gland surgery can cause a lot of its hormones to be released as a response to you playing with the glands in the surgery and this will affect the stability of the patient

Question 23

What is the nerve innervation of the adrenal cortex?

Answer 23

Only by the vasomotor innervation

• Preganglionic nerves arising from spinal cord 🡪 travel through the sympathetic trunk 🡪 through the celiac ganglia 🡪 postganglionic nerves to the blood vessels present in the cortex to supply vasomotor innervation

Question 24

What is the nerve supply of the medulla?

Answer 24

The preganglionic sympathetic fibers, which arise from the lateral horn of the grey matter of spinal segments (T10-L1) - Sympathetic chain - Celiac ganglion - Celiac plexus - Medulla (chromaffin cells "postganglionic without axon & dendrites")

Question 25

What is the lymphatic drainage of the adrenal glands?

Answer 25

The para-aortic lymph nodes

Question 26

Describe the histological layers of the cortex of the adrenal gland

Answer 26

- The cortex is yellowish in color - The cortex contains a lot of fat in their cytoplasm - This division is based on their shape and the things they secrete - CGFR 1) Capsule (most superior) 2) Zona glomerulosa (oval balls) 3) Zona fasciculata (columns) 4) Zona reticularis (very messy all around the place) -Then the Adrenal medulla

Question 27

What are the different functions of the adrenal cortex?

Answer 27

- Made up of hormone-secreting epithelial columns, between which connective tissue, blood vessels, and nerves run radially from the cortex toward the medulla, All three layers form steroid hormones, called corticosteroids (Mineralocorticoids, Glucocorticoids, Gonadocorticoids) 1) Zona glomerulosa: Secretes mineralcorticoids (aldosterone) 2) Zona fasciculate: Secretes glucocorticoids (cortisol), and some small amount of androgen 3) Zona reticularis: Secretes androgens (like dehydroepiandrosterone) and small amount of corticosteroids

Question 28

What does the adrenal medulla secrete?

Answer 28

Catecholamines (like epinephrine and norepinephrine)

Question 29

What is the histological structure of the cells of the zona glomerulosa?

Answer 29

Columnar/pyramidal (inverted columns with capillaries), they secrete aldosterone "mineralocorticoid"

Question 30

What is the histological structure of the zona fasiculata?

Answer 30

Polyhedral cells that are arranged in one or two layers with capillaries in between (they secrete glucocorticoids "cortisol"

Question 31

What is the histological structure of the zona reticularis?

Answer 31

Irregularly arranges cluster of cells that secretes androgens