Embryo (incl. Branchial)

Question 1

Derivative of first aortic arch

Answer 1

Maxillary artery

1st is MAXimal

Question 2

Derivative of second aortic arch

Answer 2

Stapedial

Second is Stapedial

Question 3

Derivative of third aortic arch

Answer 3

Common Carotid
internal Carotid

3Cs: C is the 3rd letter

Question 4

Derivative of the fourth aortic arch

Answer 4

Aortic arch (left)
Right subclavian

Arteries that go to the 4 limbs

Question 5

Derivative of sixth branchial arch

Answer 5

Pulmonary artery
Pulmonary-to-systemic shunt (ductus arteriosus)

What’s left? the lungs.

Question 6

Derivative of first branchial cleft

Answer 6

External auditory meatus

Question 7

Derivative of second-fourth branchial clefts

Answer 7

Temporary cervical sinuses

- Obliterated by proliferation of 2nd arch mesenchyme

Question 8

Derivatives of the 1st branchial arch: cartilage

Answer 8

Meckel’s cartilage
Mandible
Malleus & incus
spheno-Mandibular ligament

Question 9

Derivatives of the 1st branchial arch: muscles

Answer 9

Muscles of Mastication:

• teMporalis
• Masseter
• Medial and lateral pretygoids
• Mylohyoid
• ant. belly of digastric
• tensor tympani
• tensor veli palatini

Question 10

Derivatives of the 1st branchial arch: nerves

Answer 10

CN V2 & V3 (chew)

Question 11

Derivatives of the 1st branchial arch: abnormalities

Answer 11

Treacher Collins Syndrome

• 1st arch neural crest fails to migrate
• Mandibular hypoplasia, facial abnormalities

Question 12

Derivatives of the 2nd branchial arch: cartilage

Answer 12

Stapes
Styloid process
leSSer horn of hyoid
Stylohyoid ligament

Question 13

Derivatives of the 2nd branchial arch: muscles

Answer 13

Stapedius
Stylohyoid
platySma
belly of digastric

Question 14

Derivatives of the 2nd branchial arch: nerves

Answer 14

CN VII (facial expression, Smile)

Question 15

Derivatives of the 2nd branchial arch: abnormalities

Answer 15

Congenital pharyngo-cutaneous fistula

• Persistence of cleft and pouch
• Fistula between tonsillar area and lateral neck

Question 16

Derivatives of the 3rd branchial arch: cartilage

Answer 16

Greater horn of hyoid

Question 17

Derivatives of the 3rd branchial arch: muscles

Answer 17

Stylopharyngeus

Question 18

Derivatives of the 3rd branchial arch: nerves

Answer 18

CN IX Glossopharyngeal

Innervates stylopharyngeus–swallow stylishly

Question 19

Derivatives of the 4th-6th branchial arches: cartilage

Answer 19

Thyroid, cricoid, arytenoid, corniculate, cuneiform

Question 20

Derivatives of the 4th-6th branchial arches: muscles

Answer 20

4th: pharyngeal constrictors, cricothyroid, levator veli palatini
6th: all intrinsic muscles of larynx except cricothyroid

Question 21

Derivatives of the 4th-6th branchial arches: nerves

Answer 21

4th: CN X Vagus, Superior Laryngeal Branch
6th: CN X Vagus, Recurrent Laryngeal Branch

Question 22

Derivatives of the 4th-6th branchial arches: abnormalities

Answer 22

Arches 3 and 4 form posterior 1/3 of tongue

Question 23

Derivates of the first branchial pouch

Answer 23

Ear: middle ear cavity, eustachain tube, mastoid air cells

Question 24

Derivatives of the second branchial pouch

Answer 24

Tonsils: epithelial lining of palatine tonsils

Question 25

Derivatives of the third branchial pouch

Answer 25

Dorsal wings > inferior parathyroids

Ventral wings > thymus

Question 26

Derivatives of the fourth branchial pouch

Answer 26

Dorsal wings > superior parathyroids