Week 10.0 - Development of midline structures Flashcards Preview

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Flashcards in Week 10.0 - Development of midline structures Deck (21)
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1
Q

What is the sella turcica?

A

-The bony pocket where the pituitary sits

2
Q

What is the infundibulum with regards to pituitary development?

A

-A downward outgrowth of the forebrain which gives rise to the posterior pituitary and the neural stalk

3
Q

What is rathke’s pouch?

A

-An outpocketing of ectoderm of the stomatodeum which grows dorsally towards the developing forebrain and becomes the anterior pituitary after ossification of the skull

4
Q

Describe how the pharayngeal arches contribute to the development of the tongue

A

1) Mesenchyme proliferations in each of the pharyngeal arches appear in the floow of the oral cavity at the same time as the palate develops
- Ph A1-> two lateral swellings and medial tuberculum impat
- Ph A2,3 and 4 -> cupola
- Ph A4 (6) -> epiglottal swelling
2) Lateral swellings overgrow TI and the 3rd arch copula overgrows the 2nd
3) Extensive degeneration by apoptosis occurs freeing the tongue from the oral cavity (lingual frenulum)

5
Q

What tethers the tongue to the floor?

A

-Lingual frenulum

6
Q

What/where is sulcus terminalis?

A

-grooves on the posterior 1/3 of the tongue

7
Q

What/where is foramen cecum?

A

-Demarkation on the tongue where sulcus terminalis meet. denotes the point of descent of the thyroid

8
Q

Describe the sensory innervation to the tongue

A
  • Ant 2/3 -> special sensory = chorda tympani (VII), general sensory = V3 (lingual branch)
  • Post 1/3 gen and special = CNIX (small section by CNX)
9
Q

Through what part of the ear does chorda tympani pass? What is the clinical significance of this?

A
  • Middle ear

- Can affect taste in otitis media and other middle ear infections

10
Q

From where do the muscles of the tongue develop?

A

-Myogenic precurors of occipital somites which migrate into the developing tongue

11
Q

Describe the motor innervation of the tongue

A

-Hypoglossal

12
Q

Where does the primordia of the thyroid gland appear?

A

-In the floor of the pharynx between tuberculum impar and cupola

13
Q

Describe the descent of the thyroid gland

A
  • Begins at what is later the foramen cecum and bifurcates and descends as a bi-lobed diverticulum connected by an isthmus
  • Remains connected to tongue during descent by thyroglossal duct
  • Looses patency after developed
14
Q

What is a pyramidal lobe of the thyroid?

A

-Normal variant which remains in 50% of the population and is associated with a remnant of the thyroglossal duct

15
Q

What is a thyroglossal cyst?

A

-Cyst which forms in a persistent thyroglossal duct

16
Q

Why can the development of the thyroid gland make it possible to get ectopic thyroid tissue?

A
  • Remnants of the thyroglossal duct

- Failed descent of all or part of the thyroid

17
Q

Name some differentials of swellings in the neck (not tumour)

A
  • Branchial cyst
  • Thyroid goitre
  • Cerivcal lymphadenopathy
  • Thyroglossal cyst
18
Q

What is the cause of a cleft lip and palate?

A

-Failed fusion of the FNP with the palatal shelves of the maxillary prominence of the 1st Ph A

19
Q

What is first arch syndrome?

A

-A spectrum of defects in development involving the eyes, ears mandible and palate as a result of failed colonisation of the 1st Ph A with neural crest cells

20
Q

What is treacher-collins syndrome?

A
  • Form of first arch syndrome which is an autosomal dominant condition
  • Characterised by hypoplasia of the mandible and facial bones
21
Q

What is di-george syndrome?

A
-Disorder of the pharyngeal pouches resulting in congenital thymic aplasia and absence of the parathyroid gland due to abnormal development of neural crest cells
CATCH 22 (deletion of Chromosome 22)
-Cardiac abnormality
-Abnormal facies
-Thymic aplasia
-Cleft palate
-Hypoparathyroidism