Anatomy

Question 1

Location of the hypophysis

Answer 1

Encased in the sphenoid bone
- Sella turcica

Inferior to the hypothalamus
- Connected by the infundibulum

Posterior to the optic chiasm

Question 2

Structure of hypophysis

Answer 2

Divided into
- Neurohypophysis, posterior–> Neural down-growth of the diencephalon

• Adenohypophysis, anterior–> Outpouch of ectoderm, Rathke’s pouch (oral cavity)

Question 3

Function of the hypophysis

Answer 3

Master gland

- Secretes hormones to to all glands, control their secretion.

Question 4

Arterial supply to the hypophysis

Answer 4

Superior and Inferior hypophyseal artery
- From ICA

Superior supplies

• Median eminence
• Upper infundibulum

Inferior supplies

• Neurohypophysis
• Lower infundibulum

Arteries supplying the infundibulum and median eminence end as capillary plexus as the anastomose.

Question 5

Venous drainage of the hypophysis

Answer 5

Portal system

Capillary plexus at the stalk ending and median eminence drain into portal veins.

• Form secondary capillary plexus at the anterior pituitary.
• Allows substances from the hypothalamus to reach the anterior pituitary.

Question 6

Compare hormonal from neurotransmission

Answer 6

Hormonal—> Release of hormones

• Much slower
• Transported every in the body via circulatory system

Neurones–>Neural impulse, using neurotransmitters

• Very fast (1-2ms)
• Act locally from pre to postsynaptic neurones, microns apart

Question 7

Thyroid location

Answer 7

Anterior to the trachea
- Lateral to thyroid cartilage

Recurrent laryngeal nerves passes deep to the posteromedial surface of the lobes.

Question 8

Type of endocrine glands [3]

Answer 8

Discrete- separate and distinct. Only secretes hormones

• Hypophysis
• Thyroid and parathyroid
• Adrenal

Larger glands- both exocrine and endocrine function

• Pancreas
• Kidney
• Ovaries/ testes
• Placenta

Diffuse neuroendocrine
- Nerve cells with endocrine function

Question 9

Anatomy of thyroid

Answer 9

Two lobes joined by the isthmus

• Covers 5-6 cartilage rings
• Covers cricoid and lower cartilage

Question 10

Arterial supply of the thyroid

Answer 10

Superior thyroid
- From external carotid

Inferior thyroid
- From thyrocervical trunk (subclavian)

Question 11

Venous drainage of the thyroid gland

Answer 11

Plexus drains into the superior, middle and interior thyroid veins.

Thyroid veins drain into

• Internal jugular (superior and middle)
• Brachiocephalic (inferior)

Question 12

Development of the thyroid

Answer 12

Endodermal origin

- From the floor of the pharynx, near the base of the tongue

Question 13

Thyroid function

Answer 13

Release of thyroid hormones that regulate growth and development- T3, T4
- Under the control of TRH and TSH from the hypothalamus and anterior pituitary

Question 14

Cricothyrotomy

Answer 14

Incision in the cricothyroid membrane to establish patent airway.

Question 15

Parathyroid location

Answer 15

Deep to the lateral lobes of the thyroid
- Posterior aspect of the thyroid capsule.

Can also be located elsewhere between the carotid bifurcation and the mediastinum.

Question 16

Parathyroid origin

Answer 16

Third pharyngeal pouch
- inferior parathyroid

Fourth pharyngeal pouch
- Superior parathyroid

The pouches grow caudally towards the thymus to their adult positions.

Question 17

Anatomy of the parathyroid gland

Answer 17

2 pairs- 4 altogether

• Superior and inferior
• Very small- 40mg, size of the grain of rice.

Question 18

Arterial supply of the parathyroid

Answer 18

Mainly inferior thyroid artery
- From Thyrocervical trunk (subclavian)

Superior thyroid
- From external carotid

Question 19

Venous drainage of parathyroid

Answer 19

Superior, middle and thyroid veins

- Drains into Internal jugular and brachiocephalic

Question 20

Nervous supply of the parathyroid

Answer 20

Middle and inferior cervical ganglion.

Question 21

Function of the parathyroid

Answer 21

Composed predominantly of epithelial chief cells
- Secretes PTH

PTH regulates blood calcium and phosphate levels.

Question 22

Parathyroid implication of thyroidectomy

Answer 22

Parathyroid MUST be conserved
- Unless calcium and phosphate regulation is disrupted.

Leads to hypocalcaemia–> Tetanic contraction—> death.

Question 23

Adrenal gland location

Answer 23

Superior to kidneys

• At T12 level
• Retroperitoneal

Question 24

Adrenal gland gross anatomy

• Shape
• Layers
• Size

Answer 24

Left gland—> Semilunar

Right gland—> Pyramidal

Layers

• Outer capsule
• Cortex
• Medulla

Size
- 3.5-5g

Question 25

Adrenal gland orgin

Answer 25

Medulla---> Neural function - Neural crest origin Cortex---> Exocrine - Mesodermal orgin

Question 26

Adrenal medulla function

Answer 26

Release of catecholamines - NA and ADR from chromaffin cells Cells act are modified sympathetic post-ganglionic Release of catecholamines= fight or flight - Raised HR, BP - Relaxation of SM viscera.

Question 27

Adrenal cortex function

Answer 27

Release of adrenal corticosteroids and adrenal androgens - Glucocorticoids, from zona fasciculata---> Maintains blood glucose concentration - Mineralocorticoids, from zona glomerulosa---> Maintains Na+ levels Secretion of hormones under the control of ACTH, RAS.

Question 28

Adrenal medulla ANS

Answer 28

Receives direct preganglionic fibres from the sympathetic trunk - Allows fast fight-or-flight response Impulse--->release of Ach--> Chromaffin cells---> Release of NA, ADR Also receives post-ganglionic fibres from coeliac ganglion - Supplies blood vessels that penetrates the cortex

Question 29

Arterial supply of the adrenal gland

Answer 29

Superior suprarenal artery - From Inferior phrenic Middle suprarenal - From aorta Inferior suprarenal - From renal Arteries branch before entering capsule Cortex - Arteries branch into subcapsular plexus---> sinusoids Medulla - Arteries pass through cortex, into medulla---> Cortical activity can influence medulla

Question 30

Venous drainage of the adrenal glands

Answer 30

Adrenal veins - Drain into IVC (R) - Drain into left renal vein (L)