Development of Midline Structures Flashcards Preview

ESA 4 - Head and Neck > Development of Midline Structures > Flashcards

Flashcards in Development of Midline Structures Deck (88):
1

Where does the pituitary gland sit?

In the sella turcica, or pituitary fossa, of the sphenoid bone

2

What is the pituitary gland made up of?

Anterior and posterior lobe

3

What is the anterior lobe of the pituitary gland also known as?

Adrenohypophysis

4

What is the embryological origin of the anterior lobe of the pituitary gland?

Ectoderm

5

What kind of tissue is the anterior lobe of the pituitary gland?

Endocrine

6

What is Rathke's pouch?

Idk jono wasn't very clear

7

What is the posterior lobe of the pituitary also known as?

Neurohypophysis

8

What is the embryological origin of the posterior lobe of the pituitary?

Neuroectoderm

9

What kind of function does the posterior lobe of the pituitary have?

Neuroendocrine

10

What is the infundibulum?

Idk

11

How are the embryological origins of the anterior and posterior pituitary gland related?

They have entirely separate embryological origins, which later become structurally and functionally linked.

12

What is the posterior pituitary gland derived from?

The developing brain

13

What is the first step in the development of the posterior lobe of the pituitary gland from the developing brain?

A down-growth from the dicephalon forms in the midline, called the infundibulum

14

What happens to the part of the dicephalon from which the infundibulum arises as development proceeds?

It becomes the floor of the hypothalamus

15

What does the connection between the dicephalon and infundibulum become?

The pituitary stalk

16

Where does the infundibulum extend?

Down towards the roof of the developing oral cavity

17

What does the infundibulum retain when it extends down towards the roof of the oral cavity?

It's connection with the brain

18

How does the infundibulum retain its connection to the brain?

By the pituitary stalk

19

What develops in the pituitary stalk?

Nerve fibre tracts

20

How do nerve fibre tracts develop in the pituitary stalk?

They grow down from the hypothalamus

21

What happens simultaneously to the infundibulum forming?

An out-pouching from the roof of the oral cavity grows up to meet the infundibulum

22

What is the out-pouching that pushes out from the roof of the oral cavity to meet the infundibulum known as?

Rathke's pouch

23

What happens to Rathkes pouch once it has met the infundibulum?

It loses its connection with the roof of the mouth

24

Where does Rathke's pouch come to lie?

Anterior to the infundibulum, and wrapped around the pituitary stalk

25

What happens to the cells of Rathke's pouch?

They differentiate into the endocrine cells of the anterior pituitary

26

What functionally links the anterior lobe and posterior lobe of the hypothalamus?

A network of blood vessels, the hypophyseal portal system

27

What may persistent remnants of Rathke's pouch form?

Cysts

28

When does the tongue appear in development?

4th week

29

What does the appearance of the tongue in development coincide with?

It is about the same time as the palate begins to form

30

What appears first in development of the tongue?

Two lateral lingual swellings
Three medial lingual swellings

31

What are the lateral lingual swellings derived from?

1st pharyngeal arch

32

What are the medial lingual swellings derived from?

1st, 2nd, 3rd, and 4th pharyngeal arch

33

What part of the tongue is derived from the 1st pharyngeal arch portion of the medial lingual swellings?

Tuberculum impar

34

What part of the tongue is derived from the 2nd and 3rd pharyngeal arch portion of the medial lingual swellings?

Cupola

35

What part of the tongue is derived from the 4th pharyngeal arch portion of the medial lingual swellings?

Epiglottal swelling

36

What happens to the lateral lingual swellings as development proceeds?

They over-grow the tuberculum impar

37

What happens to the 3rd arch component of the cupola as development proceeds?

It overgrows the 2nd arch component

38

How is the tongue freed from the floor of the oral cavity?

Extensive degeneration occurs

39

What part of the tongue is not freed from the floor of the oral cavity?

Lingual frenulum

40

What is the general sensory innervation of the anterior 2/3 of the tongue?

Lingual nerve (CN VIII - mandibular branch of trigeminal)
Nerve of 1st pharyngeal arch

41

What is the general sensory innervation of the posterior third of the tongue?

Glossopharyngeal arch (CN IX)
Nerve of 3rd pharyngeal arch

42

What is the special sensory innervation to the anterior 2/3 of the tongue?

Chorda tympani (CN VII - facial nerve)

43

What pharyngeal arch is the facial nerve related to?

2nd pharyngeal arch

44

Where does the nerve of the 2nd pharyngeal arch pass?

Into the 1st pharyngeal arch, through the middle ear

45

What is the special sensory innervation of the posterior third of the tongue?

Glossopharyngeal nerve (CN IX)

46

What pharyngeal arch is the glossopharyngeal nerve associated with?

3rd

47

What are both the intrinsic and extrinsic muscles developed from?

Myogenic precursors that migrate into the developing tongue

48

What is the palatoglossus innervated by?

The vagus nerve (CN X)

49

What are all muscles of the tongue apart from the palatoglossus innervated by?

Hypoglossal nerve (CN XII)

50

What is the first endocrine gland to develop?

The thyroid gland

51

Where does the thyroid gland appear in development?

On the floor of the pharynx, between the tuberculum impar and cupola

52

What does the thyroid gland appear as in development?

An expansion of the mesenchyme

53

Where does the site of origin of the thyroid gland lie in relation to the brachial arches?

Between the 1st and 2nd

54

What is the site of origin of the thyroid gland marked by in the adult?

Foramen cecum

55

Where is the final position of the thyroid gland?

The anterior neck

56

How does the thyroid gland reach its final position from its embryonic origin?

At its point of origin, the thyroid bifurcates and descends as a bi-lobed diverticulum, connected by the itsthmus

57

What is the relationship between the thyroid gland and the tongue during its descent?

It remains connected to the tongue by the thyroglossal duct

58

What are the constituent cells of the thyroid gland?

Follicular cells
Parafollicular cells (C-cells_

59

What do the follicular cells of the thyroid gland secrete?

Thyroxine and triiodothyronine

60

What are the follicular cells of the thyroid gland formed from?

The thyroid diverticulum

61

What is the thyroid diverticulum derived from?

1st/2nd brachial arches

62

What do the parafollicular cells of the thyroid gland secrete?

Calcitonin

63

What are the parafollicular cells of the thyroid gland formed from?

The ultimobranchial body of the 4th pouch

64

What are the potential thyroid abnormalities of development?

Thyroglossal cysts and fistulae
Ectopic thyroid tissue
First arch syndrome
Di-George syndrome
CHARGE syndrome

65

Where may a thyroglossal cyst lie?

At any point along the migratory path of the thyroid gland, but always near, or in, the midline of the neck

66

What are thyroglossal cysts/fistulae?

Cystic remnants of the thyroglossal duct

67

What % of thyroglossal cysts are close to, or just inferior, to the body of the hyoid bone?

Approximately 50%

68

What is a thyroglossal fissure?

When a thyroglossal cyst is connected to the outside by a fistulouscanal, a thyroglossal fissure

69

What is the usual scenario in which a thyroglossal fissure arises?

Secondarily, after a rupture of a cyst

70

When may a thyroglossal fistula occur, other than secondary to a rupture of a cyst?

May be present at birth

71

Where may ectopic thyroid tissue be found?

Anywhere along the path of descent of the thyroid gland

72

Where is ectopic thyroid tissue commonly found?

In the base of the tongue, just behind the foramen cecum

73

What pathologies is ectopic thyroid tissue subject too?

The same as the thyroid gland itself

74

What is First Arch syndrome?

A spectrum of defects in the development of the eyes, ears, mandible, and palate

75

What is First Arch syndrome thought to result from?

Failure of colonisation of the 1st arch with neural crest cells

76

What is the presentation of First Arch syndrome known as?

Treacher-Collins syndrome

77

What is the inheritance pattern of Treacher-Collins syndrome?

Autosomal dominant

78

What is Treacher-Collins syndrome characterised by?

Hypoplasia of the mandible and facial bomes

79

What is DiGeorge Syndrome also known as?

Congential thymic aplasia

80

What is the abnormality in DiGeorge syndrome?

Absence of parathyroid hormone

81

What causes DiGeorge syndrome?

Deletion of chromosome 22

82

What are the features of DiGeorge syndrome?

Cardiac abnormality (especially tetralogy of Fallot)
Abnormal facies (not a typo)
Thymic aplasia
Cleft palate
Hypocalcaemia/hypoparathyrodism

83

What is the abnormality in CHARGE syndrome?

CHD7 heterozygous mutation

84

What does the CHD7 gene code for?

Chromodomain helicase DNA-binding domain, an ATP-dependant chromatin remodeller

85

What is CHD7 expression essential for?

The production of multipotent neural crest cells

86

What are the features of CHARGE syndrome?

Coloboma
Heart defects
Atresia (choanal)
Retardation of growth and development
Genital hypoplasia
Ear defects

87

What is coloboma?

Hole in iris

88

What is choanal atresia?

Blockage of posterior nasal cavity