ANAT 2: Anatomy of the Thyroid & Parathyroid Glands

Question 1

What connects right/left Lobes of thyroid gland?

Answer 1

Isthmus (2nd-3rd tracheal rings)

Question 2

What tethers the capsule of the Thyroid Gland?

Answer 2

Fascial Sheath (Larynx/trachea)

Suspensory Ligament of Berry (cricoid cartilage)

Question 3

Nerve of importance that passes through the thyroid?

Answer 3

Recurrent Laryngeal Nerve

Damage can lead to weakened/lost voice
(at risk in thyroid surgery)

Question 4

Arterial Supply of the Thyroid Gland?

Answer 4

Superior Thyroid Artery (Anterior-superior aspect of the gland)

Inferior Thyroid Artery (Postero-inferior part of the gland)

Thyroid Ima Artery (10%)- should be considered before tracheotomy

Question 5

Risk of Cricothyrotomy?

Answer 5

Can potentially damage cricothyroid artery (Branch of superior thyroid artery)

Question 6

Venous drainage of Thyroid Gland?

Answer 6

Superior/Middle Thyroid veins drain to Internal Jugular Vein

Inferior Thyroid Vein drains to left brachiocephalic vein

Question 7

Innervation of thyroid gland?

Answer 7

Superior/Middle/Nferior Cervical Sympathetic ganglia (Vasomotor => Constriction of blood vessels)

Endocrine secretion is hormaooly regulated by secretion of TSH from anterior Pituitary gland

Question 8

Thyroid gland development?

Answer 8

3rd week (Outpouching in the floor of pharynx => thyroid primordium)

Becomes diverticulum as cells develop

7 weeks (Definitive shape, finally located)

Question 9

What does the proximal opening of the thyroglossal duct form?

Issues with this structure?

Answer 9

Pit in tounge called Foramen Caecum

Thyroglossal Duct Cysts => Swelling in neck (ALWAYS) at midline. Lined by tissue recognizable as thyroid tissue (Diagnostic)

Question 10

What does failure of descent of the thyroid lead to?

Answer 10

Ectopic Thyroid (Can develop in any part of thyroglossal duct) => Suprahyoid, retrohyoid or infrahyoid positions

Question 11

Enlarged thyroid gland? Conseqeuneces?

Answer 11

Goitre

May compress trachea, esophagus, Recurrent laryngeal nerves

Question 12

Considerations for Thyrodectomy?

Answer 12

Relations (Recurrent Laryngeal Nerve, Superion/Inferior/Ima (10%) Arteries)

Parathyroid Glads

Question 13

Small flattened oval glands on posterior aspect of thyroid gland?

Answer 13

Parathyroid glands (4)

Question 14

What type of parathyroid cell is responsible for hormonal secretion/ What does it secrete?

Answer 14

Chief cells secrete parathyroid hormone (Calcium control)

Question 15

Development of Parathyroid Glands?

_____ Pharyngeal Pouch:

• Dorsal Part=> ______________
• Ventral Part=> _____________

___ Pharyngeal Pouch:

• Dorsal Part => ______________

Answer 15

3rd Pharyngeal Pouch:

• Dorsal Part=> Interior Parathyroid gland
• Ventral Part=> Bi-lobed Thymus

4th Pharyngeal Pouch:

• Dorsal Part => Superior Parathyroid Gland

Question 16

Blood supply of Parathyroid Glands?

Answer 16

Inferior Thyroid Arteries (Primarily)

Also STA/IMA when present