The Thyroid and Parathyroid Glands Flashcards
(23 cards)
What vertebral levels does the thyroid gland sit between?
C5 to T1
What cartilaginous structures does the thyroid sit between?
Thyroid cartilage
6th tracheal ring
Identify and name the strap muscles that sit over the thyroid gland?
- Omohyoid
- Sternohyoid
- Sternothyroid
What two nerves supply the strap muscles?
Recurrent laryngeal nerve
- Supplies everything but cricothyroid
- Runs between trachea and oesophagus
Superior laryngeal nerve
- Supplies cricothyroid
- Runs alongside sup. thyroid artery
What is the blood supply to the thyroid gland?
Sup. thyroid artery
Inf. thyroid artery
From which artery does the sup thyroid artery arise?
ECA
From which artery does the inf thyroid artery arise?
Subclavian
What is the drainage of the thyroid artery?
Sup
Middle
Inf
Thyroid veins
What do the superior and middle thyroid veins drain into?
IJV
What does the inferior thyroid vein drain into?
Left brachiocephalic
How are thyroid hormones stored in the gland?
In cavities surrounded by secretory cells
What is the cavity combined with the secretory cell collectively known as?
Follicle
How arethe thyroid hormones stored within the follicle?
Bound to glycoproteins and is known as colloid
Identify
A) Colloid
B) Follicular cells
What type of cells line the follicle?
Cuboidal epithelial cells
What are the clear cells on histology of the thyroid and what do they produce?
C cells
Secrete calcitonin
What hormones are secreted by the thyroid gland?
Thyroxine
- Triiodinothyronine (T3)
- Tetraiodinothyronine (T4)
Calcitonin
Where are the superior parathyroid glands?
- Lateral to the thyroid lobes
- Cricoid cartilage level
How many thyroid glands does the average person have?
4
What is the arterial supply and venous drainage of the parathyroids?
Via the inferior thyroid artery
- Thyroid veins to IJV
How are the parathyroid glands seperated from the thyroid?
By a thin fibrous capsule
What are the two types of cells in the parathyroid glands?
Chief cells
Oxyphil cells
What is parathyroid hormone secreted in response to and what is it’s action?
Low serum calcium
- Stimulates osteoclasts to release Ca2+ and phosphate from bone
- Inhibits osteoblasts
- Increases renal calcium reabsorption
- Increases renal phosphate secretion
- Stimulates the kidney to release calcitriol
