Thyroid Gland

Question 1

Consist of right and left lobes united to each other by the ———.

Answer 1

Isthmus

Question 2

A third lobe called ——— may project upwards from the isthmus or from one of the lobes.

Answer 2

Pyramidal

Question 3

Sometimes a band of tendon called ——descends from the body of the hyoid bone
• to the ———
•or to the ——— lobe

Answer 3

Sometimes a band (levator of the thyroid/ levator glandulae thyroidae ) descends from the body of the hyoid bone
• to the isthmus
•or to the pyramidal lobe

Question 4

————— are sometimes found as small detached masses of thyroid tissue in the vicinity of the lobes or above the isthmus

Answer 4

Accessory thyroid glands

Question 5

Situation and Extent
●The gland lies against vertebrae —- to ——, clasping the upper part of the trachea
●Each lobe extends from the middle of the ——— to the —or — tracheal ring.
●The isthmus extends from the — to the — tracheal ring.

Answer 5

Situation and Extent
●The gland lies against vertebrae C5, 6, 7 and T1, clasping the upper part of the trachea
●Each lobe extends from the middle of the thyroid cartilage to the 4th or 5th tracheal ring.
●The isthmus extends from the 2nd to the 3rd tracheal ring.

Question 6

Dimensions and Weight
●Each lobe measures about —- x —cm x —cm, and the isthmus, —-cm x —- cm.
● On an average the gland weighs about —.
● it is larger in, ——— than in ———
● further increases in size occur during ——— and ———.

Answer 6

Dimensions and Weight
●Each lobe measures about 5 cm x 2.5cm x 2.5. cm, and the isthmus, 1.2 cm x 1.2 cm.
● On an average the gland weighs about 25 g.
● it is larger in, females than in males
● further increases in size occur during menstruation and pregnancy.

Question 7

Capsules of Thyroid

Answer 7

True capsule
False capsule

Question 8

Capsules of Thyroid
●1. The true capsule is the peripheral condensation of the ————
●2. The false capsule
●derived from the ——- layer of the ——cervical fascia
●thin along the ——— border of the lobes
●thick on the ——— surface of the gland
●forms a suspensory ligament (called——-), which connects the lobe to the cricoid cartilage.

Answer 8

Capsules of Thyroid
●1. The true capsule is the peripheral condensation of the connective tissue of the gland.
●2. The false capsule
●derived from the pretracheal layer of the deep cervical fascia
●thin along the posterior border of the lobes
●thick on the inner surface of the gland
●forms a suspensory ligament (of Berry), which connects the lobe to the cricoid cartilage.

Question 9

compare the relationship of the venous plexuses related to the thyroid gland and to the prostate, with the true and false capsules around these organs.

Answer 9

For thyroid gland, the venous plexus after the true capsule
For prostrate, the venous plexus is in between true and false capsule

Question 10

A dense ——- plexus is present in the thyroid true capsule.
►To avoid haemorrhage during operations the thyroid is removed along with ———.

Answer 10

A dense capillary plexus is present in the thyroid true capsule.
►To avoid haemorrhage during operations the thyroid is removed along with capsule.
► (Compare with the prostate in which the venous plexus lies between the true capsule and the gland; and therefore during prostatectomy, the capsules are left behind).

Question 11

Relations
●The lobes are ——— in shape has:
●(a) ———, (b) a ——, (c) ——-

Answer 11

Relations
●The lobes are conical in shape has:
●(a) apex, (b) a base, (c) three surfaces

Question 12

The lateral (superficial) surface of the lobe is covered by:

Answer 12

The lateral (superficial) surface is covered by: (a) the sternothyroid; (b) sternohyoid; (c) the superior belly of the omohyoid (d) ant. border of the sternomastoid

Question 13

The medial surface of the lobe is related to:

•The posterolateral (posterior) surface of the lobe is related to

Answer 13

The medial surface is related to:
(a) 2 tubes-trachea and esophagus;
(b) 2 muscles the inferior constrictor and cricothyroid
(c) 2 nerves- the external laryngeal and recurrent laryngeal nerves
•The posterolateral (posterior)
the carotid sheath and overlaps the carotid artery.

Question 14

The apex :directed upwards and slightly laterally. Limited superiorly by the attachment of the ———— to the oblique line of the thyroid cartilage.
●The base is on level with the —th or —th. ring.

Answer 14

The apex :directed upwards and slightly laterally. Limited superiorly by the attachment of the sternothyroid to the oblique line of the thyroid cartilage.
●The base is on level with the 4th or 5th. ring.

Question 15

The Isthmus connects the lower parts of the two lobes. It has

● (a) how many surfaces, includes:
● (b)how many borders, includes:
●Occasionally the ——— is absent.

●The anterior surface is covered by:
●right & left ——- and —— muscles
● the ———veins& ——

●The posterior surface related to
●—— & ——tracheal rings.
●It may be placed at a higher, or lower level.

Answer 15

The Isthmus connects the lower parts of the two lobes. It has

● (a) 2 surfaces, anterior& posterior;
● (b) 2 borders, superior &inferior.
●Occasionally the isthmus is absent.

●The anterior surface is covered by:
●right & left sternothyroid and sternohyoid muscles
● the anterior jugular veins& fascia

●The posterior surface related to
●2nd & 3rd tracheal rings.
●It may be placed at a higher, or lower level.

Question 16

Arterial Supply
●supplied by the ———- and ——-arteries

Answer 16

Arterial Supply
●supplied by the superior and inferior thyroid arteries

Question 17

Arterial Supply
●supplied by the superior and inferior thyroid arteries
●The superior thyroid artery -1st ant. br. of the ——— artery.
● runs downwards and forwards in intimate relation to the ———nerve.
●After giving branches to adjacent structures it pierces the ——— fascia to reach the upper pole of the lobe.
●Here it divides into ——— and ——- branches

The anterior branch descends on the ——— border of the lobe
● continues along the border of the ——
●anastomose with ——— of the opposite side.
● The posterior branch descends on the ——— border of the lobe
●anastomoses with the ascending branch of the ———— artery.

Answer 17

Arterial Supply
●supplied by the superior and inferior thyroid arteries
●The superior thyroid artery -1st ant. br. of the ext. carotid artery.
● runs downwards and forwards in intimate relation to the ext. laryngeal nerve.
●After giving branches to adjacent structures it pierces the pretracheal fascia to reach the upper pole of the lobe.
●Here it divides into anterior and posterior branches
The anterior branch descends on the anterior border of the lobe
● continues along the border of the isthmus
●anastomose with its fellow of the opposite side.
● The posterior branch descends on the posterior border of the lobe
●anastomoses with the ascending branch of the inferior thyroid artery.

Question 18

The inf. thyroid artery: br. of the ——— trunk
•Runs 1st upwards , medially
• and downwards to reach the —— pole of the gland.
•Passes
•behind the ——— and the ———-
• in front of the ——— and gives off br. to adjacent structures.

Terminal part is intimately related to the ————.
•Artery divides into — or — glandular branches which pierce the fascia separately to reach the —— part of the gland

One ascending branch anastomoses with the posterior branch of the superior thyroid artery, and supplies the parathyroid glands.

●The superior thyroid artery supplies the upper — of upper —of the isthmus; and Inf. thyroid artery supplies the lower lobe and the lower — of the isthmus

●The superior and inferior thyroid artery anastomose through their branches

Answer 18

The inf. thyroid artery: br. of the thyrocervical trunk (from the subclavian art.)

•Runs 1st upwards
• medially
• and downwards to reach the lower pole of the gland.
•Passes
•behind the carotid sheath and the middle cervical sympathetic ganglion
• in front of the vertebral vessels and gives off br. to adjacent structures.

Terminal part is intimately related to the recurrent laryngeal nerve.
•Artery divides into 4 or 5 glandular branches which pierce the fascia separately to reach the lower part of the gland

One ascending branch anastomoses with the posterior branch of the superior thyroid artery, and supplies the parathyroid glands.

●The superior supplies the upper 1/3 of upper 1/2 of the isthmus; and Inf. thyroid artery supplies the lower lobe and the lower 1/2 of the isthmus

●The superior and inferior thyroid artery anastomose through their branches

Question 19

Venous Drainage
•The thyroid is drained by the ——— and ——— veins.
•The superior thyroid vein apical pole and accompanies the artery: drains into the ——— vein or in the —— vein.
•The ——— vein is a channel which emerges at the middle of isthmus and soon enters the ——— vein.

Inferior thyroid veins emerge at the —— part of the isthmus.
● form a ——- in front of the trachea
●drain into the ———— vein.
●A fourth thyroid vein (called——) may occur between the middle and inferior veins
● drain into the ———- vein.

Answer 19

Venous Drainage
•The thyroid is drained by the superior and inferior thyroid veins.
•The superior thyroid vein apical pole and accompanies the artery: drains into the internal jugular vein or in the facial vein.
•The middle thyroid vein is a channel which emerges at the middle of isthmus and soon enters the internal jugular vein.

Inferior thyroid veins emerge at the lower part of the isthmus.
● form a plexus in front of the trachea
●drain into the left brachiocephalic vein.
●A fourth thyroid vein (of Kocher) may occur between the middle and inferior veins
● drain into the internal jugular vein.

Question 20

Large goiters are prevalent in areas of ———

Answer 20

Large goiters are prevalent in areas of iodine deficiency

Question 21

Normal anatomy of the recurrent laryngeal nerve.
•on the right side the recurrent laryngeal nerve hooks around behind the ———
•on the left side this nerve passes around behind the ———- before ascending in the neck.

Answer 21

Normal anatomy of the recurrent laryngeal nerve.
•on the right side the recurrent laryngeal nerve hooks around behind the subclavian artery
•on the left side this nerve passes around behind the aortic arch before ascending in the neck.

Question 22

in a vascular anomaly of the right subclavian artery, the recurrent laryngeal nerve no longer “recurs” around this artery
•It proceeds in what manner? .

Answer 22

) in a vascular anomaly of the right subclavian artery, the recurrent laryngeal nerve no longer “recurs” around this artery
•It proceeds from the vagus nerve in a more transverse direction to the larynx.
• the nerve is much more likely to be damaged during operation unless care is taken to visualize its course in the neck.

Question 23

Lymphatic Drainage
●Lymph from the upper part of the gland reaches —— lymph nodes either directly or through the ——— nodes. Lymph from lower part reaches ——— nodes directly, and also through the —— and ——— nodes.

Answer 23

Lymphatic Drainage
●Lymph from the upper part of the gland reaches upper deep cervical lymph nodes either directly or through the prelaryngeal nodes. Lymph from lower part lower deep cervical nodes directly, and also through the pretracheal and paratracheal nodes.

Question 24

Nerve Supply
•Nerves are derived mainly from the ———- and partly also from the ——— & ————-.
–These are secretomotor T or F

Answer 24

Nerve Supply
•Nerves are derived mainly from the middle cervical ganglion and partly also from the superior & inferior cervical ganglia.
–These are secretomotor.

Question 25

The thyroid gland is made up of 2 types of secretory cells:

Answer 25

The thyroid gland is made up of 2 types of secretory cells:
Follicular cells
Parafollicular(C) cells

Question 26

The thyroid gland is made up of 2 types of secretory cells:
•Follicular cells lining the ——— of the thyroid secrete ———— and ——— which stimulate ———-.

Parafollicular cells (C cells) lie in between the ———. They secrete ———- which promotes the ————.
•NOTE
•Parathormone effects —are opposite to those of ———

Answer 26

The thyroid gland is made up of 2 types of secretory cells:
•Follicular cells lining the follicles of the thyroid secrete tri-iodothyronin and tetra-iodothyronin (thyroxin) which stimulate basal metabolic rate and somatic and psychic growth of the individual.

Parafollicular cells (C cells) lie in between the follicles. They secrete thyrocalcitonin which promotes the deposition of calcium salts in skeletal and muscular tissues, and tends to produce hypocalcemia.
•NOTE
•Parathormone effects —are opposite to those of thyrocalcitonin

Question 27

Development
●The thyroid develops from a ————
● grows down in front of the neck from the floor of the primitive ———
●just caudal to the ———.

●The lower end of the diverticulum enlarges to form the ——-.
●The rest of the diverticulum remains narrow and is known as the ——- duct.

Most of the duct soon disappears.
● The position of the upper end is marked by the ——— of the tongue
● the lower end often persists as the ———.

Thyroid tissue may develop at abnormal sites along the course of the duct resulting in:.

●——— thyroids may be present

●Remnants of the thyroglossal duct
●may form thyroglossal cysts
●thyroglossal fistula.

Answer 27

Development
●The thyroid develops from a median endodermal thyroid diverticulum
● grows down in front of the neck from the floor of the primitive pharynx
●just caudal to the tuberculum impar.

●The lower end of the diverticulum enlarges to form the gland.
●The rest of the diverticulum remains narrow and is known as the thyroglossal duct.

Most of the duct soon disappears.
● The position of the upper end is marked by the foramen caecum of the tongue
● the lower end often persists as the pyramidal lobe.

●Remnants of the thyroglossal duct
●may form thyroglossal cysts
●thyroglossal fistula.

Thyroid tissue may develop at abnormal sites along the course of the duct resulting in lingual
● retrosternal thyroids.

●Accessory thyroids may be present

Question 28

Applied Anatomy
•Any enlargement of the thyroid gland is called a ———.

•2. Removal of the thyroid (called——-) may be necessary in ————

Answer 28

Applied Anatomy
•Any enlargement of the thyroid gland is called a goitre.

•2. Removal of the thyroid (thyroidectomy) may be necessary in hyperthyroidism

Question 29

hyperthyroidism can also be called——-

Answer 29

thyrotoxicosis

Question 30

In partial thyroidectomy
●——— parts of both lobes are left behind
●This avoids the risk of simultaneous removal of the ———
●and also of postoperative ——— caused by deficiency of ——-/ hormones

Answer 30

In partial thyroidectomy
●posterior parts of both lobes are left behind
●This avoids the risk of simultaneous removal of the parathyroids
●and also of postoperative myxoedema caused by deficiency of thyroid hormones

Question 31

During operation the superior thyroid artery is ligated (near/far away ?) the gland to save the ——— nerve
the inferior thyroid artery is ligated( near/far away?) from the gland to save the ———- nerve

Answer 31

During operation the superior thyroid artery is ligated near the gland to save the external laryngeal nerve
the inferior thyroid artery is ligated away from the gland to save the recurrent laryngeal nerve

Question 32

Hypothyroidism causes —— in infants and ——— in adults.

Benign tumours of the gland may do what to adjacent structures?.

Malignant growths tend to do what?

Pressure symptoms and nerve involvements are common in ——- of the gland

Answer 32

Hypothyroidism causes cretinism in infants and myxoedema in adults.

Benign tumours of the gland may displace and even compress neighbouring structures, like the carotid sheath, the trachea, etc.
Malignant growths tend to invade and erode neighbouring structures.

Pressure symptoms and nerve involvements are common in carcinoma of the gland

Question 33

——— causes cretinism in infants and myxoedema in adults.

Answer 33

Hypothyroidism causes cretinism in infants and myxoedema in adults.

Question 34

The lower pole of the thyroid gland extends along the side of the trachea as low as the —— tracheal ring

Answer 34

sixth tracheal ring

Question 35

The upper pole of the thyroid cannot normally rise above the level of the ——of thyroid cartilage

Answer 35

Oblique line

Question 36

Superior thyroid artery
• entersdeepto ——— muscle

Answer 36

Superior thyroid artery
• entersdeepto sternothyroid

Question 37

The recurrent laryngeal nerve always lies behind the ———- fascia

Answer 37

The recurrent laryngeal nerve always lies behind the pre- tracheal fascia

Question 38

Thyroidae ima artery
• In about —% of individuals, an unpaired artery, the thyroidae ima is a small occasional artery from the ———, or ——— artery, or direct from the ——

Answer 38

Thyroidae ima artery
• In about 10% of individuals, an unpaired artery, the thyroidae ima is a small occasional artery from the brachiocephalic trunk, or left common carotid artery, or direct from the arch of the aorta

Question 39

Thyroidae ima artery
• The possible presence of the thyroid ima artery must be remembered when incising the trachea inferior to the ——.
• As the thyroidae ima runs anterior to the ——-, it is a potential source of serious bleeding

Answer 39

Thyroidae ima artery
• The possible presence of the thyroid ima artery must be remembered when incising the trachea inferior to the isthmus.
• As the thyroidae ima runs anterior to the trachea, it is a potential source of serious bleeding

Question 40

Thyroglossal cyst
• cystsderivedfromthe duct may also appear anywhere between the foramen cecum and the normal position in the midline of the neck, the different positions are:

Answer 40

Thyroglossal cyst
• cystsderivedfromthe duct may also appear anywhere between the foramen cecum and the normal position in the midline of the neck
1. Beneath foramen cecum
2. Floor of the mouth
3. Suprahyoid
4. Subhyoid
5. On thyroid cartilage
6. At level of cricoid cartilage

Question 41

Thyroglossal cyst
• Canbediagnosed because
characteristically when it does what in relation to the movement of the tongue

Answer 41

Thyroglossal cyst
• Canbediagnosed because
characteristically it moves upwards as the patient puts his tongue out.

Question 42

Ectopic thyroid
• Failure of descent mar result in a superior cervical thyroid in the region of the ——- bone
• thethyroidmay sometimes descended too far and be found in the ——-

Answer 42

Ectopic thyroid
• Failure of descent mar result in a superior cervical thyroid in the region of the hyoid bone
• thethyroidmay sometimes descended too far and be found in the superior mediastinum

Question 43

Parathyroid glands
• how many on each side
• They are what color endocrine glands, about the size of a small —- (about —x— cm ovoids)
• They are important because of their role in ——— metabolism. They secrete parathormone that mobilizes bone calcium and increases gut and kidney calcium absorption

Answer 43

Parathyroid glands
• Two on each side
• They are yellow-brown endocrine glands, about the size of a small pea (about 0.5x0.8 cm ovoids)
• They are important because of their role in calcium metabolism. They secrete parathormone that mobilizes bone calcium and increases gut and kidney calcium absorption

Question 44

Parathyroid glands
• Are located —— to the thyroid gland between its ——- and ———

Answer 44

Parathyroid glands
• Are located posterior to the thyroid gland between its capsule and fascial sheath

Question 45

In superior parathyroid and inferior parathyroid gland, which has a variable position and which has a constant position

Answer 45

Superior parathyroid gland is more constant in position
Inferior parathyroid gland is variable in position

Question 46

Superior parathyroid glands
• embedded in the posterior surface of the thyroid gland, a short distance above the entry of —— artery (and the level of the ——- cartilage).

Answer 46

Superior parathyroid glands
• more constant in position
• embeddedinthe posterior surface of the thyroid gland, a short distance above the entry of inferior thyroid artery (and the level of the cricoid cartilage).

Question 47

Inferior parathyroid glands
• usually embedded behind the —— pole but is often found elsewhere (they may even present in the ———).

Answer 47

Inferior parathyroid glands
• variableinposition
• usuallyembedded behind the lower pole but is often found elsewhere (they may even present in the superior mediastinum).

Question 48

Parathyroid glands, blood supply
• The glands are usually supplied by the ———— arteries but may also be supplied by both ——- and ——-arteries

Answer 48

Parathyroid glands, blood supply
• The glands are usually supplied by the inferior thyroid arteries but may also be supplied by both superior and inferior thyroid arteries

Question 49

Parathyroid glands
• Awarenessoftheclose relationship between the parathyroid glands and the thyroid gland is essential to prevent removal or damage of the parathyroid glands during ————.

Answer 49

thyroidectomy.