Thyroid & Parathyroid Glands

Question 1

Describe extent of thyroid glands

Answer 1

Apex at C5 (oblique line of thyroid cartilage)
Base at T1 with level of 5th or 6th tracheal rings
Isthmus extends from 2nd to 4th tracheal rings

Question 2

Levator glandylar thyroidae is remnant of…….

Answer 2

Thyroglossal duct

Question 3

List capsules of thyroid gland

Answer 3

1. Inner true capsule condensation of CT
2. Outer false capsule from pretracheal layer of deep cervical fascia

Question 4

Ant border of thyroid is related to…..while posterior is related to…..

Answer 4

Ant branch of superior thyroid artery
Inferior thyroid artery & its anastomosis with STA and parathyroid glands

Question 5

Enumerate relations of superficial surface of thyroid

Answer 5

1. Skin & fascia
2. Sternomastoid
3. Sterohyoid, sternothroid, superior belly of omohyoid

Question 6

Enumerate relations of medial surface of thyroid

Answer 6

2 tubes: esophagus & trachea
2 muscles: cricothyroid & inferior constrictor
2 nerves: external & recurrent laryngeal

Question 7

Enumerate posterolateral relations of thyroid gland

Answer 7

Carotid sheath with its contents

Question 8

Describe relations of thyroid isthmus

Answer 8

Upper border related to anastomsis of STAs + pyramidal lobe
Lower border to thyroid ima art + inferior thyroid veins
Ant related to skin, fascia, sternothyroid, sternohyoid
Post related to 2-4 tracheal rings

Question 9

Describe arterial supply of thyroid gland

Answer 9

1. Superior thyroid artery: 1st branch of ECA runs close to external laryngeal nerve
2. Inferior thyroid artery: branch of thyrocervical trunk (1st part of subclavian artery), runs close to recurrent laryngeal nerve
3. Thyroid ima a. from brachiocephalic trunk or aortic arch

Question 10

Describe venous & lymph drainage & nerve supply of thyroid gland

Answer 10

Superior & middle thyroid veins to IJV, inferior thyroid veins to left brachiocephalic vein
LD by deep cervical & pretracheal LNs
From 3 cervical sympathetic ganglia. Middle ganglion

Question 11

List precautions of thyroidectomy

Answer 11

1. Cut infra-hyoid muscles near their upper part (nerves lower)
2. Ligate STA near thyroid gland to avoid external laryngeal a
3. Ligate ITA away from thyroid gland to avoid recurrent laryngeal a
4. Avoid removal of posterior border to save parathyroids (subtotal thyroidectomy)

Question 12

…..run ant to trachea inf to isthmus & may be a source of bleeding during…..

Answer 12

Thyroid ima a & inf thyroid v
Tracheostomy

Question 13

Blood supply & LD of parathyroids

Answer 13

Inf thyroid a&v
Deep cervical LNs

Question 14

Thyroid & parathyroid are…..in origin. Thyroid begins development during…., development complete at…..and functions at……

Answer 14

Endodermal
4th week
7th week
11th week

Question 15

Thyroid develops from…..
Name its stages

Answer 15

Floor of primordial pharynx between 1st & 2nd pharyngeal pouches
Primodium-diverticulum-thyroglossal duct

Question 16

Parafollicular C cells develop from…..

Answer 16

4th pharyngeal pouch, migrating neural crest cells

Question 17

Sup parathyroid develop from…..while inf parathyroid develop from…..

Answer 17

4th pouch
3rd pouch

Question 18

The most common ectopic thyroid is……

Answer 18

Lingual thyroid

Question 19

Explain DiGeorge syndrome

Answer 19

3rd & 4th pouches syndrome
Ansence of thymus & parathyroids
Anomalies of heart
Facial defects as fish mouth & cleft lip