Anatomy

Question 1

Endocrine gland

Answer 1

Not through a duct to a surface, goes straight to bloodstream

Question 2

Examples of endocrine glands

Answer 2

 Pituitary (Two‐in‐one).
 Thyroid.
 Parathyroid.
 Adrenal / suprarenal (Two‐in‐one).
 Islets in the pancreas.
 Gonads.
 Others.
 Hypothalamus – pituitary axis adrenal cortex, gonads, thyroid.

Question 3

Relationship between pituitary and optic chiasm

Answer 3

Optic chasm is directly anterior to the gland

Question 4

Pituitary - hypophysis parts

Answer 4

Neurohypophysis (posterior)
- Hypothalamus cells produce hormones and stored in NH for release
Adenohypophysis (anterior)
- Hypothal releasing hormones, hypophyseal portal system
- specialised cells for each hormone

Question 5

Adrenal - parts

Answer 5

Cortex: intermediate mesoderm

• zona glomerulosa (outer)
• zona fasciculata
• zona reticularis

Medulla: neural crest cells
- produce noradrenaline and adrenaline

Question 6

Thyroid location and structure

Answer 6

Anterior part of neck

2 lobes, separated by isthmus (pyramidal lobe from isthmus is variable)

Question 7

Venous drainage of the thyroid

Answer 7

Venous drainage is carried out by the superior, middle and inferior thyroid veins, which form a venous plexus. The superior and middle veins drain into the internal jugular veins, whereas the inferior drains into the brachiocephalic vein.

Question 8

Thyroid cells

Answer 8

Secretory cells form follicles - spherical structures, cuboidal columnar epithelium (T3/4)

Parafollicular cells - large cells with clear cytoplasm and produce calcitonin

Question 9

What is the anterior pituitary derived from and what are the thee parts?

Answer 9

Derived from an outpouching of Rathke’s pouch

1. pars anterior
2. pars intermedia
3. pars tuberalis

Question 10

How does the hypothalamus communicate with the anterior pituitary?

Answer 10

Via neurotransmitters secreted into the hypophyseal portal vessels

Question 11

What does the posterior lobe of the pituitary arise from? and where are ADH and oxytocin produced and stored?

Answer 11

Derived from the embryonic forebrain

Produced in the supraoptic and paraventricular nuclei of hypothalamus and stored in posterior pituitary gland

Question 12

Describe the vascular supply of the pituitary gland

Answer 12

Anterior and posterior venous drainage: anterior and posterior hypophyseal veins

Arterial supply of Anterior p: superior hypophyseal artery (first forms capillary network around hypothalamus and then transported to form capillary plexus around anterior pituitary) - known as hypothalamus-hypophyseal portal system

Arterial supply of posterior pituitary: receives a rich blood supply from many arteries including the superior hypophyseal artery, infundibular artery and hypophyseal artery

Question 13

Anatomical location of thyroid

Answer 13

Vertebrae: C5-T1

Tracheal rings: 2-3

Question 14

Arterial supply of the thyroid

Venous drainage

Answer 14

2 main arteries:
superior (branch of external carotid) - supplies the superior and anterior portions of the gland

Inferior thyroid arteries (branch of subclavian) - supplies the poster-inferior aspect

Venous drainage: superior, middle and inferior thyroid veins form and plexus. Superior and middle drain into internal jugular and inferior drains into brachiocephalic

Question 15

Clinical relevance of innervation of and around the thyroid

Answer 15

Innervation: by branches derived from sympathetic trunk
2 recurrent laryngeal nerves L R (Arise from respective vagus nerves) and wrap around subclavian and arch of aorta and pass underneath the thyroid gland to innervate the larynx. During surgery care must be taken to now ligate or damage the recurrent laryngeal nerves