19 - Embryology of the Head and Neck II Flashcards Preview

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Flashcards in 19 - Embryology of the Head and Neck II Deck (15)
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1
Q

What is the location of the pituitary gland and what is it’s embryological origin?

A
  • Sits in hypophyseal fossa of sella turcica in sphenoid bone

- Anterior: from ectoderm Rathke’s pouch so endocrine

- Posterior: from neuroectoderm infundibulum so neuroendocrine

2
Q

How does the pituitary gland form embryologically?

A
  • Downward outgrowth of forebrain (infundibulum) to the roof of the pharynx
  • Invagination of ectoderm at stomatodeum (Rathke’s) which grows dorsally towards forebrain
  • Sphenoid bone ossifies and pinches off the Rathke’s pouch so it can join with the infundibulum, which is still connected to the forebrain by a stalk
3
Q

What are the two structures being pointed to on the tongue?

A

Foramen cecum: remnant of where the thyroid gland developed from

Sulcus terminalis: separates the two boundaries of the tongue

4
Q

How does the tongue form embryologically?

A
  • Develops around the same time as the soft palate and recieves contributions from all 6 arches (6 insignificant)
  • 2 lateral lingual swellings (arch 1) and 3 lingual swellings arches 1 to 4
  • Lateral lingual swellings overgrow tuberculum impar and third arch overgrows cupola of 2nd arch
  • Cell degeneration at floor of oral cavity leaving lingual frenulum so tongue can move freely
5
Q

What is the sensory innervation of the tongue and how does this relate to it’s embryological origin?

A

Mucosa of anterior 2/3: V and IX as from arch 1 and 3

Posterior 1/3: IX and X as from arch 3 and 4

Taste buds: special sensory from VII (chorda tympani)

6
Q

What is the motor innervation to the tongue and where does it come from embryologically?

A

XII - Hypoglossal

Occipital somites all migrate to the tongue to innervate intrinsic and extrinsic muscles

7
Q

Where does the primordium of the thyroid gland form?

A

Between the tuberculum impar and the cupola in an area called the foramen cecum so thyroid depends on tongue to develop

8
Q

How does the thyroid gland form embryologically?

A
  • Gland differentiates and bifurcates as it descends so bilobed diverticulum joined by isthmus
  • During descent thyroid remains connected to tongue by thyroglossal duct which degenerates at final positon
9
Q

What abnormalities can arise during the embryological development of the thyroid gland?

A
  • Pyramidal lobe: 50% of population have third lobe as thyroglossal duct persists

- Thyroglossal cysts/fistula

- Ectopic thyroid tissue

10
Q

What embryonic structures contribute to the development of the face?

A
  • FNP and 1st/2nd pharyngeal arches
11
Q

In general terms how does a cleft lip and palate form?

A
  • Faliure of fusion of median nasal prominence from FNP and maxillary prominence
  • Failure of palate shelves to form
12
Q

What is the importance of neural crest cells in the development of the face?

A

They populate the cartilage bars to make up the skeleton of the face, they are susceptible to alcohol and can lost in the body when migrating

13
Q

What is Treacher Collins Syndrome? (first arch syndrome)

A
  • Failure of neural crest cells to populate 1st PA
  • Defect in development of eyes, ears, mandible and palate
  • Hypoplasia of mandible and maxilla with low set ears
  • Autosomal dominant insufficiency of treacle involved in neural crest cell migration
14
Q

What is DiGeorge syndrome?

A
  • Thymic aplasia and absence of parathyroid glands
  • CATCH 22 deletion
  • Disruption of 3rd and 4th PA
  • Difficulty regulating Ca levels and infections
15
Q

What is CHARGE syndrome?

A
  • CHD7 mutation that is normally needed for production of multipotent neural crest cells