ANATOMY AND HISTOLOGY OF ENDOCRINE ORGANS

Question 1

how is the pituitary gland attached to the brain?

Answer 1

by the infundibulum- stalk attaching it to the hypothalamus

Question 2

why can an enlargement of the pituitary gland cause visual impairments?

Answer 2

as its close to the optic chiasm so any enlargement can put pressure on the optic nerve

Question 3

what is the optic chiasm?

Answer 3

an X-shaped structure formed by the crossing of the optic nerves in the brain

Question 4

describe the structure of the pituitary gland?

Answer 4

it consists of an anterior and posterior lobe and sits within the sella turcica

Question 5

where is the anterior lobe of the pituitary gland derived from?

Answer 5

oral ectoderm of the primitive oral cavity

Question 6

where is the posterior lobe of the pituitary gland derived from?

Answer 6

neuroectoderm of the diencephalon

Question 7

describe the embryology of the pituitary gland?

Answer 7

The oral ectoderm moves upwards and the neuroectoderm of the diencephalon grows downwards. These tissues coalesce and the diverticulum of the oral ectoderm closes and should seal up. This gives rise to the anterior and posterior lobes-

Question 8

what is the arterial supply to the pituitary gland?

Answer 8

inferior and superior hypophyseal artery

Question 9

where does the venous blood from the pituitary gland drain into?

Answer 9

the cavernous sinus

Question 10

describe the structure of the anterior lobe of the pituitary gland?

Answer 10

endocrine cells surrounded by a rich capillary bed

connected to the primary capillary plexus at the top of the stalk via the hypophyseal portal vein

Question 11

describe how the hypothalamus interacts with the anterior pituitary?

Answer 11

axons from the hypothalamus release neurohormones into the capillary plexus and then these neuro-hormones ass through the hypophyseal portal system and target the endocrine cells, stimulating the secretion of hormones into the cavernous sinus

Question 12

describe the posterior pituitary gland’s structure?

Answer 12

a bundle of axons surrounded by a rich blood supply, the axons from the hypothalamus terminates ere

Question 13

how does the hypothalamus interact with the posterior pituitary?

Answer 13

neurohormones from the hypothalamic axons are released directly into the arterial system

Question 14

describe the structure of the thyroid gland

Answer 14

a right and a left lobe connected by a central isthmus

in some cases it can contain a pyramidal lobe too

Question 15

where is the thyroid gland located?

Answer 15

at the level of the cricoid cartilage C6

Question 16

what is the thyroid gland encased in?

Answer 16

the pretracheal fascia

Question 17

what’s the arterial supply to the thyroid gland?

Answer 17

the superior thyroid artery and the inferior thyroid artery (from the subclavian artery)

Question 18

describe the venous drainage of the thyroid gland?

Answer 18

drains into the superior, middle and inferior thyroid veins

Question 19

what do the superior and middle thyroid veins drain into?

Answer 19

The internal jugular vein

Question 20

what does the inferior thyroid vein drain into?

Answer 20

the brachiocephalic vein

Question 21

describe the embryology of the thyroid gland?

Answer 21

the thyroid forms in an invgaination of the oral ectoderm- they thyroglossal duct continues down into the invagination, leaving behind the foramen caecum.
when it gets to in front of the hyoid bone it starts to form a big pit and the duct disintegrates

Question 22

why might we get cysts in the midline of the neck?

Answer 22

if the thyroglossal duoesnt seal up properly (thyroglossal duct cysts)

Question 23

why might we get solid masses in the midline of the neck?

Answer 23

they could be ectopic remnants from the descent of the thyroid

Question 24

whats the histology of the thyroid gland?

Answer 24

epithelial cells surrounding follicles

Question 25

where do we tend to find the parathyroid glands?

Answer 25

we tend to see 2 superior and 2 inferior within the capsule of the thyroid posteriorly. or sometimes within the thyroid itself.

Question 26

what is the vasculature of the parathyroid gland?

Answer 26

the same as the thyroid (can vary depending on positioning of parathyroid glands)

Question 27

describe the histology of the parathyroid gland?

Answer 27

contains chief cells and oxyphil cells

Question 28

where are the superior and inferior parathyroid glands derived from?

Answer 28

4th pharyngeal pouch becomes the superior parathyroid

3rd pharyngeal pouch becomes the inferior parathyroid