1.2 The Thyroid and Parathyroid Gland Flashcards
Where is the Thyroid Gland located?
In the Neck:
- Anterior to the Trachea
- Inferior to the Larynx
Between which Vertebral Levels can the Thyroid Cland be found?
C5 to T1
Where can the Thyroid Gland be found between?
- The Cricoid Cartilage
2. The 6th Tracheal Ring
What are the Parts of the Thyroid Gland?
- The Left Lobe
- The Right Lobe
- The Isthmus
What does the Isthmus do?
Connects the Left and Right Lobe of the Thyroid
Which Tracheal Ring does the Isthmus lie opposite to?
The 2nd to the 3rd Tracheal Rings
What are the 3 Strap Muscles which overlie the Thyroid?
- Sternohyoid
- Sternothyroid
- Omohyoid
What are the 2 Nerves which supply the Muscles of the Vocal Cord?
- The Superior Laryngeal Nerve
2. The Recurrent Laryngeal Nerve
Where does the Superior Laryngeal Nerve run?
From an inferior Ganglion of the Vagus Nerve, Lateral to the Thyroid and then enters into the Thyroid by the Cricoid Cartilage
Where does the Recurrent Larngeal Nerve run?
From inferior to the Thyroid (around the level of the Heart), up to the Thyroid between the Trachea and the Oesophagus
What Arteries supply the Thyroid?
- The Superior Thyroid Artery
2. The Inferior Thyroid Artery
Where does the Superior Thyroid Artery arise from?
The External Carotid Artery
Where does the Inferior Thyroid Artery arise from?
The Thyrocervical Trunk (A Branch of the Subclavian Artery)
What Veins drain the Thyroid?
- The Superior Thyroid Vein
- The Middle Thyroid Vein
- The Inferior Thyroid Vein
Into which vein does the Superior Thyroid Vein drain?
The Internal Jugular Vein
Into which vein does the Middle Thyroid Vein drain?
The Internal Jugular Vein
Into which vein does the Inferior Thyroid Vein drain?
The Left Braciocephalic Vein
Where does the Lymph from the Thyroid Gland drain to?
The Deep Cervical Lymph Nodes
Where are the Hormones of the Thyroid Gland stored?
In Cavities surrounded by Secretory Cells
What is the name of the Cavity and Secretory Cells?
The Follicle
What happens within the Cavity of the Follicle?
The Hormone created is bound to a Glycoprotein
What is the new name for the Hormone bound to the Glycoprotein?
The Colloid
What happens during secretion of the Hormone?
IT is re-absorbed from the Cavity and released into the surrounding Interstitial Space
What separated the Follicles?
Fibrous Septae
What type of Cells line the Follicle?
Follicular Cells
What is the Cell Type of Follicular Cells?
Simple Columnar Epithelium
What colour does the Colloid stain?
Pink
What secretes Calcitonin?
Parafollicular (C) Cells
What is the action of Calcitonin?
Calcitonin reduces Serum Calcium Levels
How does Calcitonin reduce Serum Calcium Levels?
- Inhibiting the Activity of Osteoclasts
2. Decrease Calcium re-absorption at the Kidneys
What Hormones does the Thyroid Gland secrete?
T3 - Triiodothyronine
T4 - Thyroxine
Where do the Parathyroid Hormones lie?
The Medial part of the Posterior Surface of Each Thyroid Lobe
How is the Parathyroid Gland related to the Thyroid Gland?
It is External to (and separated by) the thin Thyroid Fibrous Capsule
How many Parathyroid Hormones do most people have?
4
What is the Arterial Supply to the Superior and Inferior Parathyroid Glands?
The Inferior Thyroid Arteries
Which Vein drains the Parathyroid Glands?
The Veins draining the (Superior and Middle) Thyroid to the Internal Jugular Vein
What are the 2 Cell Types present in the Parathyroid Gland?
- The Chief Cells
2. The Oxyphil Cells
Are there more of fewer Chief Cells than Oxyphil Cells?
More
Do the Chief Cells stain Darker or Lighter than the Oxyphil Cells?
Darker
Are the Chief Cells Larger or Smaller than the Oxyphil Cells?
Smaller
What is the function of the Parathyroid Chief Cells?
To Secrete Parathyroid Hormone
What is the Parathyroid Hormone associated with?
Calcium Homeostasis
How does the Parathyroid Hormone influence Calcium Homeostasis?
It increases the action of Osteoclasts (Bone Re-modelling) which increases the Plasma Calcium Levels
What is the function of the Parathyroid Oxyphil Cells?
There is no known function