Pharyngeal Arches

Question 1

What are the 4 structures of the pharyngeal apparatus?

Answer 1

Arches, Pouches, Grooves/Clefts, Membrane.

Question 2

Where do neural crest cells derive from? Where do they migrate to and how do they differentiate?

Answer 2

Derive from the lateral edges of the neural plate. Migrate from the posterior region of the neural tube to the anterior region. they have their own genetic code for development.

Question 3

What is the Stomadaeum and primitive pharynx separated by?

Answer 3

The buccopharyngeal (oropharyngeal) membrane.

Question 4

Most of the oral cavity will develop from which germ layer?

Answer 4

Ectoderm

Question 5

What are made up of what material inside, middle, and out?

Answer 5

Mesenchyme is encased in external Ectoderm and internal Endoderm.

Question 6

What is contained in each pharyngeal arch?

Answer 6

Nerve, Artery, Cartilage, and muscle components.

Question 7

Arch 1 includes what prominence?

Answer 7

The maxillary and Mandibular prominence.

Question 8

What arches contain what arteries?

Answer 8

I: Maxillary Artery
II: Stapedial artery (embryonic) Corticotymphanic (adult)
III: Carotid Artery
IV: Arch of Aorta and R subclavian artery
VI: Ductus Arteriosus, pulmonary arteries.

Question 9

What arches contain Cartilage/Skeletal elements?

Answer 9

I: Incus, Malleus, Maxilla, Zygomatic, Tempora bone, Mandible.
II: Stapes, Syloid process, Lesser horn of hyoid.
II: Greater Horn of Hyoid.
IV: Laryngeal cartilage/Thyroid
VI: Laryngeal cartilage/Cricoid.

Question 10

What arches form which muscles?

Answer 10

I:Muscles of Mastication 
II: Muscles of Facial Expression 
III: Stylopharyngeus 
IV: Constrictors of pharynx
VI: Intrinsic muscles of larynx

Question 11

What arches form what cranial nerves?

Answer 11

I: Maxillary and Mandibular branch of Trigeminal nerve V
II: Facial Nerve VII
III: Glossopharayngeal nerve IX
IV:Superior Laryngeal Vagus nerve X
VI: Recurrent Laryngeal vagus nerve X

Question 12

What are derivatives?

Answer 12

Formations originating from Clefts/Grooves (Ectoderm) and pouches (endoderm).

Question 13

What does cleft 1 do?

Answer 13

Forms External Auditory meatus.

Question 14

What happens to clefts 2-4?

Answer 14

Arch 2 grows over remaining clefts, and clefts 2-4 form the cervical sinus.

Question 15

Cervical cysts appear where?

Answer 15

On the lateral sides of the neck

Question 16

What do pouches 1-4 form?

Answer 16

1: Pharyngotympanic tube (internal auditory canal).
2: Palatine tonsils
3: Inferior parathyroid gland and thymus
4: Superior parathyroid gland and ultimo branchial body

Question 17

What are the derivatives/migration of pouch 3 and 4?

Answer 17

3: Inf Parathyroid gland joins Inf posterior border of thryroid. Thymus descends to forgut
4: Sup parahtyroid gland joins superior border of thyroid. Ultimobranchial body joins the thryroid.

Question 18

What is the purpose of the ultimobranchial body?

Answer 18

Joins the thyroid to form follicular C Cells that produce Calcitonin.

Question 19

Where does the primitive thyroid form? What does its migration form?

Answer 19

Forms at the midline of the pharynx. Forms the thyroglossal duct.

Question 20

Thyroglossal Duct cysts form where?

Answer 20

The midline of the neck.