Anatomy of the thyroid and parathyroid Flashcards

1
Q

Where does the thyroid sit in relation to the spine?

A

Anteriorly to C7

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2
Q

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

A

Isthmus

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3
Q

Where do the two lobes of the thyroid attach to?

A

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

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4
Q

Where does the isthmus lie?

A

Between anterior 2nd and 3rd cartilages of the trachea

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5
Q

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

A

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

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6
Q

How many parathyroid glands are there?

A

4

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7
Q

Where are the parathyroid glands situated?

A

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

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8
Q

What is the thyroid covered by?

A

Thin fibrous capsule which sends septa deeply into the gland

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9
Q

What do septa contain?

A

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

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10
Q

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

A

Dense connective tissue

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11
Q

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

A

Cricoid cartilage and superior tracheal rings

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12
Q

What is external to the fibrous capsule?

A

Loose fascial sheath

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13
Q

How is the loose fascial sheath formed?

A

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

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14
Q

Where does the thyroid gland begin its development?

A

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

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15
Q

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

A

Foramen caecum

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16
Q

Where does the thyroid gland migrate to during developement?

A

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

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17
Q

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

A

Via the thyroglossal duct

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18
Q

When does the thyroid gland reach its final position?

A

7 weeks of development

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19
Q

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

A

At any point in the migratory path

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20
Q

Where does a pyramidal lobe most commonly originate from?

A

Left lateral lobe

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21
Q

What is the prevalence of pyramidal lobe?

A

About 45%

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22
Q

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

A

True

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23
Q
  1. Where do most pyramidal lobes attach superiorly? 2. Where may the pyramidal lobe extend as far superiorly as?
A
  1. Thyroid cartilage 2. Hyoid bone
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24
Q

Define platysma

A

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

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25
Q

Where are the platysma muscles located?

A

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

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26
Q

What group of muscles do the platysma muscles belong to?

A

Fascial expression

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27
Q

What nerve supplies the platysma muscles?

A

Facial nerve

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28
Q

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

A

Investing (deep) fascia

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29
Q

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

A

Prevertebral (deep) fascia

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30
Q

What is shown in red?

A

Carotid sheath

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31
Q

What fascial compartment of neck is shown in purple?

A

Pretrachial (deep) fascia

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32
Q

What muscle sits posterior to the neck?

A

trapezius

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33
Q

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

A

Sternocleidomastoid

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34
Q

Where does the retropharyngeal space run from and to?

A

Base of skull to superior mediastinum

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35
Q

How fast will infection spread in the retropharyngeal space?

A

Extremely quickly

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36
Q

Where is the prevertebral (deep) fascia located?

A

Deep to investing fascia

Located posteriorly

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37
Q

What does the prevertebral fascia enclose?

A

The cervical vertibrae and postural neck muscles

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38
Q

What does the investing (deep) fascial compartment enclose?

A

All neck fascial compartments

2 pairs of muscles - R and L trapezius and anteriorly sternocleidomastoid

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39
Q

Where is the investing fascia located?

A

Deep to superficial fascia

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40
Q

How many carotid sheaths are there?

A

2

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41
Q

Where are the carotid sheaths located?

A

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

42
Q

What do the carotid sheaths enclose?

A
  • Internal jugular veins
  • Carotid arteries
  • Vagus nerves
  • Deep cervical lymph nodes
43
Q

Where does the pretracheal (deep) fascia lie?

A

Anteriorly, deep to the investing fascia

44
Q

What does the pretracheal fascia enclose?

A
  • Strap muscles
  • Thyroid gland
  • Trachea
  • Oesophagus
  • Recurrent laryngeal nerves
45
Q

Where dot he carotid sheaths attach superoirly?

A

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

46
Q

How do carotid sheaths attach inferiorly?

A

Blend inferiorly with mediastinal fascia

47
Q

What nerve supplies the sternocleidomastoid?

A

CN XI - spinal accessory nerve

48
Q

What nerve supplies the trapezius?

A

CN XI - spinal accessory nerve

49
Q

Where does the anterior jugular vein drain into?

A

External jugular vein

50
Q

Where does the external jugular vein drain into?

A

Subclavian vein

51
Q

Where does the sternal head of the sternocleidomastoid?

A

Manubrium of sternum

52
Q

Where does the clavicular head attach to of the sternocleidomastoid?

A

Medial end of the clavicle

53
Q

Where do both heads of the sternocleidomastoid attach to superiorly?

A

mastoid process of the temporal bone

54
Q

What two arteries supply the thyroid?

A

Inferior and superior thyroid arteries

55
Q

What artery supplies the parathyroid glands?

A

Inferior arteries supply both inferior and superior parathyroid glands

56
Q

What are internal jugular veins a branch of?

A

Brachiocephallic veins

57
Q

What veins drain the thyroid gland?

A

Superior, middle and inferior thyroid veins

58
Q

Where do the superior and middle thyroid veins drain into?

A

Internal jugular vein

59
Q

Where do the inferior thyroid veins normally drain into?

A

Left brachiocephallic vein

60
Q

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

A

Superior deep cervical lymph nodes

61
Q

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

A

Inferior deep cervical lymph nodes

62
Q

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

A

Pretracheal node

63
Q

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

A

Paratracheal nodes

64
Q

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

A

Via the right lymphatic duct to the right venous angle

65
Q

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

A

Returned via the thoracic duct to the left venous angle

66
Q

Describe the lymphatic drainage of the thyroid and parathyroid glands

A

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

67
Q

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

68
Q

Where does the left recurrent laryngeal nerve recur?

A

Under the arch of the aorta

69
Q

Where does the right recurrent laryngeal nerve recur?

A

Under the subclavian artery

70
Q

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

A

Jugular foramen

71
Q

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

A
  1. Superior laryngeal nerve
  2. Right recurrent laryngeal nerve
72
Q

Where does the vagus nerve exit the brain?

A

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

73
Q

Describe the route of the right vagus nerve

A
  • Right lateral aspect of trachea
  • Posterior to right lung route
  • Forms plexus onto the oesophagus
74
Q

Describe the route of the left vagus nerve

A
  • Left side of the arch of the aorta
  • Posterior to the lung route
  • Forms plexus onto the oesophagus
75
Q

Where do both vagus nerves pass through?

A

The diaphragm along with the oesophagus

76
Q

Where do the vagus nerves divide into terminal branches?

A

Surface of the stomach

77
Q

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

A

The vagus nerves

78
Q

How many strap muscles are there?

A

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

79
Q

What is another name for the strap muscles?

A

Infrahyoid muscles

80
Q

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

A

Omohyoid

Attaches to the hyoid bone and the scapula

81
Q

What are the names of the 4 strap muscles

A
  1. Superior belly of omohyoid
  2. Inferior belly of omohyoid
  3. Sternohyoid
  4. Thyrohyoid
82
Q

What does the fascial sling attach?

A

The intermediate tendon of the omohyoid to the clavicle

83
Q

What are the four surgical approaches to the thyroid gland?

A
  • Classical thyroidectomy (similar approach to tracheostomy)
  • Endoscopically assisted thyroidectomy
  • Endoscopic trans-axillary approach
  • Endoscopic trans-breast approach
84
Q

Describe the process of thyroidectomy

A

A collar incision is made within a natural skin creaseor Langer’s lines

Incision should be just superior to the clavicles and jugular notch

85
Q

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

A

Optimal aesthetics as the scar is hidden behind clothing

Reduces risk of keloid formation

86
Q

Define a keloid

A

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

87
Q

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

A

Through the skin and platysma

88
Q

What is A on this diagram?

A

Anterior jugular veins (in superficial fascia)

89
Q

What is B on this diagram?

A

Right sternohyoid

90
Q

What is C on this diagram?

A

Sternal head of the right sternocleidomastoid

91
Q

What is D on this diagram?

A

Laryngeal prominence of the thyroid cartilage

92
Q

What is E on this diagram?

A

Left sternohyoid

93
Q

What is F on this diagram?

A

Pretrachial fascia

94
Q

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

A

In the groove between the trachea anteriorly and oesophagus posteriorly

95
Q

Describe how you would remove the thyroid gland

A

Mobilise the thyroid gland anteriorly

Dissect parathyroid glands

Dissect their blood supply free from the posterior surface of the gland

96
Q

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

A

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

97
Q

What does injury to the recurrent laryngeal nerve cause?

A

Paralysis of the vocal cord

98
Q

What is the rima glottidis?

A

Opening between the vocal cords

99
Q

What does unilateral damage of the recurrent laryngeal nerve cause?

A

Hoarseness or weakness of the voice and a weak cough

100
Q

What does bilateral injury to the recurrent laryngeal nerve cause?

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