Anatomy of the thyroid and parathyroid

Question 1

Where does the thyroid sit in relation to the spine?

Answer 1

Anteriorly to C7

Question 2

What is the name of the narrow band that connects between the two lobes of the thyroid?

Answer 2

Isthmus

Question 3

Where do the two lobes of the thyroid attach to?

Answer 3

Lateral aspects of the thyroid and cricoid cartilages as well as to the trachea

Question 4

Where does the isthmus lie?

Answer 4

Between anterior 2nd and 3rd cartilages of the trachea

Question 5

How will a lump in the thyroid gland or an enlarged gland move when a patient swallows?

Answer 5

Superiorly then inferiorly with the larynx This is due to the relationship between larynx, trachea and thyroid

Question 6

How many parathyroid glands are there?

Answer 6

4

Question 7

Where are the parathyroid glands situated?

Answer 7

On the posterior surfaces of the thyroid gland’s LATERAL lobes, external to fibrous capsule

Question 8

What is the thyroid covered by?

Answer 8

Thin fibrous capsule which sends septa deeply into the gland

Question 9

What do septa contain?

Answer 9

Larger blood vessels, lymphatics and nerves that enter the thyroid gland

Question 10

What attaches the fibrous capsule to the cricoid cartilage and superior tracheal rings?

Answer 10

Dense connective tissue

Question 11

What does dense connective tissue attach the fibrous capsule surrounding the thyroid to?

Answer 11

Cricoid cartilage and superior tracheal rings

Question 12

What is external to the fibrous capsule?

Answer 12

Loose fascial sheath

Question 13

How is the loose fascial sheath formed?

Answer 13

By the visceral portion of the pretracheal layer of deep cervical fascia

Question 14

Where does the thyroid gland begin its development?

Answer 14

At the junction between the anterior 2/3rd and posterior 1/3 of the tongue, as a midline epithelial proliferation

Question 15

What is the junction between the anterior 2/3 and posterior 1/3 of the tongue called in adults?

Answer 15

Foramen caecum

Question 16

Where does the thyroid gland migrate to during developement?

Answer 16

It migrates inferiorly, whilst remaining attached to tongue via the thyroglossal duct

Question 17

In its development, how does the tongue remain attached to the tongue as it migrates inferiorly?

Answer 17

Via the thyroglossal duct

Question 18

When does the thyroid gland reach its final position?

Answer 18

7 weeks of development

Question 19

Where can thyroid duct cysts or ectopic thyroid tissue be located?

Answer 19

At any point in the migratory path

Question 20

Where does a pyramidal lobe most commonly originate from?

Answer 20

Left lateral lobe

Question 21

What is the prevalence of pyramidal lobe?

Answer 21

About 45%

Question 22

9% of pyramidal lobes arent connected with main thyroid gland. True or false?

Answer 22

True

Question 23

1. Where do most pyramidal lobes attach superiorly? 2. Where may the pyramidal lobe extend as far superiorly as?

Answer 23

1. Thyroid cartilage 2. Hyoid bone

Question 24

Define platysma

Answer 24

Skeletal muscle in the superficial fascia, runs near thyroid gland laterally

Question 25

Where are the platysma muscles located?

Answer 25

Located immediately deep to the skin, within the superfiscial fascia of the neck, from lower border of mandible down the neck

Question 26

What group of muscles do the platysma muscles belong to?

Answer 26

Fascial expression

Question 27

What nerve supplies the platysma muscles?

Answer 27

Facial nerve

Question 28

What is the name of the fascial compartment shown in green?

Answer 28

Investing (deep) fascia

Question 29

What is the name of the fascial compartment shown in orange?

Answer 29

Prevertebral (deep) fascia

Question 30

What is shown in red?

Answer 30

Carotid sheath

Question 31

What fascial compartment of neck is shown in purple?

Answer 31

Pretrachial (deep) fascia

Question 32

What muscle sits posterior to the neck?

Answer 32

trapezius

Question 33

What are the muscles seen at the anterior edge of the neck?

Answer 33

Sternocleidomastoid

Question 34

Where does the retropharyngeal space run from and to?

Answer 34

Base of skull to superior mediastinum

Question 35

How fast will infection spread in the retropharyngeal space?

Answer 35

Extremely quickly

Question 36

Where is the prevertebral (deep) fascia located?

Answer 36

Deep to investing fascia Located posteriorly

Question 37

What does the prevertebral fascia enclose?

Answer 37

The cervical vertibrae and postural neck muscles

Question 38

What does the investing (deep) fascial compartment enclose?

Answer 38

All neck fascial compartments 2 pairs of muscles - R and L trapezius and anteriorly sternocleidomastoid

Question 39

Where is the investing fascia located?

Answer 39

Deep to superficial fascia

Question 40

How many carotid sheaths are there?

Answer 40

2

Question 41

Where are the carotid sheaths located?

Answer 41

Anterolaterally deep to the investing fascia, either side of the thyroid gland

Question 42

What do the carotid sheaths enclose?

Answer 42

* Internal jugular veins * Carotid arteries * Vagus nerves * Deep cervical lymph nodes

Question 43

Where does the pretracheal (deep) fascia lie?

Answer 43

Anteriorly, deep to the investing fascia

Question 44

What does the pretracheal fascia enclose?

Answer 44

* Strap muscles * Thyroid gland * Trachea * Oesophagus * Recurrent laryngeal nerves

Question 45

Where dot he carotid sheaths attach superoirly?

Answer 45

The base of the skull (around the jugular foramen and entrance to carotid canal)

Question 46

How do carotid sheaths attach inferiorly?

Answer 46

Blend inferiorly with mediastinal fascia

Question 47

What nerve supplies the sternocleidomastoid?

Answer 47

CN XI - spinal accessory nerve

Question 48

What nerve supplies the trapezius?

Answer 48

CN XI - spinal accessory nerve

Question 49

Where does the anterior jugular vein drain into?

Answer 49

External jugular vein

Question 50

Where does the external jugular vein drain into?

Answer 50

Subclavian vein

Question 51

Where does the sternal head of the sternocleidomastoid?

Answer 51

Manubrium of sternum

Question 52

Where does the clavicular head attach to of the sternocleidomastoid?

Answer 52

Medial end of the clavicle

Question 53

Where do both heads of the sternocleidomastoid attach to superiorly?

Answer 53

mastoid process of the temporal bone

Question 54

What two arteries supply the thyroid?

Answer 54

Inferior and superior thyroid arteries

Question 55

What artery supplies the parathyroid glands?

Answer 55

Inferior arteries supply both inferior and superior parathyroid glands

Question 56

What are internal jugular veins a branch of?

Answer 56

Brachiocephallic veins

Question 57

What veins drain the thyroid gland?

Answer 57

Superior, middle and inferior thyroid veins

Question 58

Where do the superior and middle thyroid veins drain into?

Answer 58

Internal jugular vein

Question 59

Where do the inferior thyroid veins normally drain into?

Answer 59

Left brachiocephallic vein

Question 60

What are the yellow structures that look like dots on this diagram?

Answer 60

Superior deep cervical lymph nodes

Question 61

What is the name of the purple dots on this diagram?

Answer 61

Inferior deep cervical lymph nodes

Question 62

What is the name of the red dot on this diagram?

Answer 62

Pretracheal node

Question 63

What is the name of the green dots on this diagram?

Answer 63

Paratracheal nodes

Question 64

On the right hand side, how is the lymph drained?

Answer 64

Via the right lymphatic duct to the right venous angle

Question 65

How does lymph drain on the left hand side of thyroid?

Answer 65

Returned via the thoracic duct to the left venous angle

Question 66

Describe the lymphatic drainage of the thyroid and parathyroid glands

Answer 66

Initially pass to the prelaryngeal, pretracheal and paratracheal lymph nodes Drain into superior and inferior deep cervical lymph nodes Right - lymphatic duct then right venous angle Left - thoracic duct then left venous angle

Question 67

In the neck, is the vagus nerve medial or lateral to the recurrent laryngeal nerve

Answer 67

Lateral

Question 68

Where does the left recurrent laryngeal nerve recur?

Answer 68

Under the arch of the aorta

Question 69

Where does the right recurrent laryngeal nerve recur?

Answer 69

Under the subclavian artery

Question 70

Where does the vagus nerve exit the base of the skull?

Answer 70

Jugular foramen

Question 71

What somatic branches does the vagus nerve give to the larynx in the neck?

Answer 71

1. Superior laryngeal nerve 2. Right recurrent laryngeal nerve

Question 72

Where does the vagus nerve exit the brain?

Answer 72

An extension of the spinal cord into the brain called the **medulla oblongata**

Question 73

Describe the route of the right vagus nerve

Answer 73

* Right lateral aspect of trachea * Posterior to right lung route * Forms plexus onto the oesophagus

Question 74

Describe the route of the left vagus nerve

Answer 74

* Left side of the arch of the aorta * Posterior to the lung route * Forms plexus onto the oesophagus

Question 75

Where do both vagus nerves pass through?

Answer 75

The diaphragm along with the oesophagus

Question 76

Where do the vagus nerves divide into terminal branches?

Answer 76

Surface of the stomach

Question 77

What nerve supplies the abdominal organs with parasympathetic axons to the distal midgut?

Answer 77

The vagus nerves

Question 78

How many strap muscles are there?

Answer 78

8 in total, 4 on the left and 4 on the right

Question 79

What is another name for the strap muscles?

Answer 79

Infrahyoid muscles

Question 80

What is the most lateral strap muscle and what are its attachments?

Answer 80

Omohyoid Attaches to the hyoid bone and the scapula

Question 81

What are the names of the 4 strap muscles

Answer 81

1. Superior belly of omohyoid 2. Inferior belly of omohyoid 3. Sternohyoid 4. Thyrohyoid

Question 82

What does the fascial sling attach?

Answer 82

The intermediate tendon of the omohyoid to the clavicle

Question 83

What are the four surgical approaches to the thyroid gland?

Answer 83

* Classical thyroidectomy (similar approach to tracheostomy) * Endoscopically assisted thyroidectomy * Endoscopic trans-axillary approach * Endoscopic trans-breast approach

Question 84

Describe the process of thyroidectomy

Answer 84

A collar incision is made within a natural skin creaseor Langer's lines Incision should be just superior to the clavicles and jugular notch

Question 85

Why should a thyroidectomy incision be just superior to the clavicles and jugular notch?

Answer 85

Optimal aesthetics as the scar is hidden behind clothing Reduces risk of keloid formation

Question 86

Define a keloid

Answer 86

A scar that grows lumpy or larger than the wound that is healing

Question 87

In a thyroidectomy, what layers is the incision made in?

Answer 87

Through the skin and platysma

Question 88

What is **A** on this diagram?

Answer 88

Anterior jugular veins (in superficial fascia)

Question 89

What is B on this diagram?

Answer 89

Right sternohyoid

Question 90

What is **C** on this diagram?

Answer 90

Sternal head of the right sternocleidomastoid

Question 91

What is **D** on this diagram?

Answer 91

Laryngeal prominence of the thyroid cartilage

Question 92

What is **E** on this diagram?

Answer 92

Left sternohyoid

Question 93

What is **F** on this diagram?

Answer 93

Pretrachial fascia

Question 94

Where does the right recurrent laryngeal nerve ascend in the neck?

Answer 94

In the groove between the trachea anteriorly and oesophagus posteriorly

Question 95

Describe how you would remove the thyroid gland

Answer 95

Mobilise the thyroid gland anteriorly Dissect parathyroid glands Dissect their blood supply free from the posterior surface of the gland

Question 96

Where does the right recurrent laryngeal nerve provide somatic motor supply to?

Answer 96

Most of the skeletal muscles that move the right vocal cord (intrisic muscles of the larynx)

Question 97

What does injury to the recurrent laryngeal nerve cause?

Answer 97

Paralysis of the vocal cord

Question 98

What is the rima glottidis?

Answer 98

Opening between the vocal cords

Question 99

What does unilateral damage of the recurrent laryngeal nerve cause?

Answer 99

Hoarseness or weakness of the voice and a weak cough

Question 100

What does bilateral injury to the recurrent laryngeal nerve cause?

Answer 100

* Aphonia (inability to make sound) * Inability to close the rima glottidis * Can no longer prevent aspiration or produce a good cough