Pharyngeal Mesoderm

Question 1

1st arch

Answer 1

From brainstem
CN V

From mesoderm
Aortic arch I (maxillary a.)
Skeletal muscle: muscles of mastication, tensors, anterior digastric and mylohyoid

From neural crest
Maxilla, zygomatic, squamous temporal, palatine and vomer, plus the mandible, malleus, and incus (Meckel’s)

Question 2

2nd arch

Answer 2

From brainstem
CN VII

From mesoderm
Aortic arch II (stapedial a.)
Muscles of fascial expression plus stapedius, posterior digastric, stylohyoid

From neural crest
stapes, styloid process, lesser horn of hyoid and upper hyoid body (Reichert’s)

Question 3

3rd arch

Answer 3

From brainstem
CN IX

From mesoderm
Aortic arch III (part of internal carotid)
Stylopharyngeus

From neural crest
greater horn of hyoid and lower body

Question 4

4th arch

Answer 4

From brainstem
CN X (superior laryngeal)

From mesoderm
Parts of right subclavian and the aortic arch
Soft plate mm except tensor palati
pharyngeal muscles except stylopharyngeus and the cricothyroid

From neural crest
laryngeal cartilages

Question 5

6th arch

Answer 5

From brainstem
CN X (recurrent laryngeal)

From mesoderm
ductus arteriosus and pulmonary aa.
Intrinsic laryngeal mm. except cricothyroid and esophageal mm.

From neural crest
laryngeal cartilages

Question 6

Frontonasal

Answer 6

forehead, nose, nasal septum, philtrum of upper lip, primary palate, 4 upper incisors