3.1.2 Branchial Arches

Question 1

What fraction of birth abnormalties involve craniofacial defects?

Answer 1

1/3

Question 2

What are branchial pouches?

Answer 2

Endodermal outpocketings

Question 3

Answer 3

Question 4

Describe the ebryonic orgin of the tongue

Answer 4

Top 2/3 of tongue: 1st

Posterior 1/3 of tongue: 3rd

Most posterior: 4th-6th

Question 5

What CN are associated with the pharygeal arches: 1, 2, 3, 4-6?

Answer 5

1st arch: CN V

2nd arch: CN VII

3rd arch: CN IX

4-6 arches: CN X

Question 6

Answer 6

Question 7

How many branchial/pharyngeal arches are there?

Answer 7

4-6

Question 8

What comprises branchial arches?

Answer 8

mesenchymal core (mesoderm and neural crest) in b/t clefts and pounches

Question 9

Where do the pharyngeal arches sit in relation to the pharyngeal clefts/pouches?

Answer 9

The pharyngeal arches sit rostral to their respective clefts/pouches. Thus, the first pharyngeal arch sits rostral to the first cleft/pouch.

Question 10

Age of development? What is covered?

Answer 10

Question 11

How is the general sensation of the tongue distributed?

Answer 11

Anterior 2/3: CN V₃

Posterior 1/3: CN IX

Extreme Posterior: CN X

Epiglottis: CN X

Question 12

How is taste distributed throughout the tongue?

Answer 12

Anterior 2/3: CN VII

Posterior 1/3: CN IX

Epiglottis: CN X

Question 13

What are the muscle derivatives of the pharyngeal arches?

Answer 13

First arch: muscles of mastication/ anterior belly of digastric

2nd arch: muscles of facial expression/posterior belly of digastric

3rd: stylopharyngeus
4th: pharyngeal and laryngeal

Question 14

Fill in this chart.

Answer 14

Question 15

Which aortic arches orginate from the pharyngeal arches? What is the adult derivative of those arches?

Answer 15

1st and 2nd: degenerate

3rd in 3rd: internal carotid

4th in 4th: subclavian on R, portion of arch of aorta on L

6th in 6th: pulmonary arteries (ductus arteriosus)

Question 16

What is being covered? Where will it be found along the neck?

Answer 16

Pharyngeal cyst; laterally

Question 17

What is the innervation of the branchial arches?

Answer 17

1st branchial arch: CN V

2nd branchial arch: CN VII

3rd branchial arch: CN IX

4th branchial arch: CN X

Question 18

Age of development? What is covered?

Answer 18

Question 19

Answer 19

Cervical sinus

Question 20

What two structures play an important role in the mirgration of the thyroid?

Answer 20

Top: Foramen cecum

Bottom: Thyroglossal duct

Question 21

What is the intrinsic motor innervation of the tongue?

Answer 21

Intrinsic musculature: CN XII (Hypoglossal)

Palatoglossus: CN X (pharyngeal plexus)

Question 22

What are the 4 possible consituents of a branchial arch?

Answer 22

Artery (aortic arch), nerve (cranial nerve), muscle (mesoderm-derivative), cartilage (neural crest derivative)

Question 23

Answer 23

C

Question 24

What age of development? ID the parts

Answer 24

Question 25

Answer 25

Question 26

What are branchial clefts?

Answer 26

Ectodermal ingrowths

Question 27

Know the cartilages

Question 28

Age of development? What is covered?

Answer 28

Neural crest cells migrate into the ultimobranchial body which forms from the ventral part of the 4th pouch or the 5th pouch (if it forms in humans). The C cells of the thyroid are therefore derived from neural crest cells. Please note the vertical transposition of the parathyroids developing from the 3rd and 4th pouches. Note: They are vertically transposed during embryogenesis. This is significant in function-preserving parathyroidectomy, because both the superior and the inferior parathyroids are supplied by the inferior thyroid artery. If the surgeon is to leave a single functional parathyroid for the patient, he/she must preserve the appropriate blood supply. Neural crest cells migrate into the ultimobranchial body which forms from the ventral part of the 4th pouch or the 5th pouch (if it forms in humans). The C cells of the thyroid are therefore derived from neural crest cells. Please note the vertical transposition of the parathyroids developing from the 3rd and 4th pouches. Note: They are vertically transposed during embryogenesis. This is significant in function-preserving parathyroidectomy, because both the superior and the inferior parathyroids are supplied by the inferior thyroid artery. If the surgeon is to leave a single functional parathyroid for the patient, he/she must preserve the appropriate blood supply.

Question 29

What are these images of?

Answer 29

Branchial (pharyngeal) fistula

Question 30

Where in the neck?

Answer 30

Top: Lateral Bottom: Midline

Question 31

Fill in this chart

Answer 31

Question 32

How old is this embryo?

Answer 32

28 days