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GAS - Embryology of the Pharyngeal Arches

Terms in this set (23)

Insufficient migration of the neural crest cells into the first pharyngeal arch results in what malformations?
First Arch Syndrome - Mandibulofacial dystosis

Cheek malformations
Hypoplasia of mandible
Macrostomia (small mouth)
Given that in DiGeorge's syndrome, individuals lack a thymus gland -- this results from a problem with which arch?
3rd/4th arch
Maxillary Prominence = Upper first arch while Mandibular Prominence = Lower first arch - True or False?
True
Opening that will eventually give rise to the mouth:
Stomodeum
Space between two pharyngeal arches on the inside; outside:
Pouch; Cleft
3 streams of neural crest cells migrate down into the pharyngeal arches -- and set up innervation to each -- outline the innervation for the arches:
1st arch -- CN V (trigeminal)
2nd arch -- CN VII (facial)
3rd arch -- CN IX (glosspharyngeal)
4th/6th arch -- CN X (vagus)
Explain the concept of epithelial mesenchymal interaction with respect to the formation of the different skeletal elements of the face and pharynx:
Endodermal factors regulated the differentiation of pharyngeal arch mesenchyme to specific skeletal elements.

Response of the mesenchyme however is dependent on transcription factors expressed in that mesenchyme.
Pouch that gives rise to the palatine tonsil:
2nd pouch
Pouch that gives rise to the parathyroid gland and thymus gland:
3rd pouch
Pouch that gives rise to the Parathyroid tissue
4th Pouch
The 4th pouch gives rise to the ______ PT gland while the 3rd pouch gives rise to the ______ PT land:
superior; inferior

The 3rd pouch migrates down below the 4th pouch
Develops on the tongue and migrates down the neck right about the cricoid cartilage:
Thyroid Gland
Why is hypocalemia associated with DiGeorge's syndrome?
Given that Digeorge's syndrome results from a lack of the 3rd and 4th arch --- there is no PT gland. PTH is responsible for Ca2+ reabsorption.
What is the fate of 1st pouch?
The 1st pouch meets the 1st cleft --- forming the external auditory meatus (i.e. the Eustachian tube)

The membrane between = tympanic membrane
The mandible is not formed from 1st arch - True or False?
True --- it's formed from intramembranous bone growth (begins in Meckel's Cartilage)
How can you differentiate between a thyroglossal and cervical cyst?
Thyroglossal cyst occur down the midline while cervical cyst occur just anterior to the sternocleidomastoid muscle.
Portion of the 4th arch that gives rise to calcitonin producing cells:
Ultimobronchial bodies
Inward growth of endoderm into arch:
Pouch
Arch that gives rise to the muscles of mastication, anterior digastric, and mylohyoid:
1st arch
Arch that gives rise to muscles of facial expression, posterior digastric and stylohyoid:
2nd arch
Arch that gives rise to stylopharyngeus:
3rd arch
Arch that gives rise to cricothyroid and pharyngeal constrictors:
4th arch
Arch that gives rise to laryngeal structures:
6th arch
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