Pharyngeal arches (embryology 1)

Question 1

what is pharyngeal arch 1 known as?

Answer 1

mandibular arch

Question 2

how does pharyngeal arch appear?

Answer 2

below FNP, largest arch (has 2 sections)

maxillary and mandibular prominences

Question 3

what does facial skeleton develop from?

Answer 3

1st Ph A + FNP

Question 4

nerve to the pharyngeal arches?

Answer 4

1st: V
2nd: VII
3rd: IX
4th + 6th: X

Question 5

what is the first arch’s cartilage? forming?

Answer 5

Meckel’s cartialge:
future mandible, malleus, incus
(provides template for mandible to form - via intramembranous ossification)

Question 6

muscles of Ph A 1?

Answer 6

muscles of mastication
mylohyoid
anterior belly of digastric
tensor tympani
tensor veli palatine

main sensory to face + NASOpharynx

Question 7

skeletal elements of Ph A 1?

Answer 7

maxillae and zygomatic bones

Question 8

what is 2nd pharyngeal arch known as?

Answer 8

hyoid arch

Question 9

muscles and sensory of Ph A 2?

Answer 9

muscles of facial expression
stapedius
stylohyoid
posterior belly of digastric

special sensory to anterior 2/3rd tongue (chorda tympani)

Question 10

cartilage of 2nd pharyngeal arch and derivatives?

Answer 10

Reichert's cartilage:
superior part of hyoid
stapes
styloid process
stylohyoid ligament

Question 11

artery of 2nd pharyngeal arch?

Answer 11

no artery to 1st + 2nd pharyngeal arches

Question 12

muscles and sensory of ph A 3?

Answer 12

stylopharyngeus (muscle of the pharynx - inner longitudinal layer)

sensory to posterior 1/3rd tongue + upper pharynx (think cupola)

Question 13

skeletal element of Ph A 3?

Answer 13

no cartilage

inferior part of body of hyoid

Question 14

skeletal element of Ph A 3 + 4?

Answer 14

epiglottis (think epiglottal swelling of tongue)

Question 15

artery to 3rd arch?

Answer 15

ICA

Question 16

innervation of Ph A 4 + 6?

Answer 16

4: superior laryngeal branch of vagus (CN X)
6: recurrent laryngeal branch of vagus

Question 17

motor + sensory innervation to Ph A 4 + 6?

Answer 17

constrictor muscle of pharynx + muscles of soft palate (levator veli palatine)
muscles of larynx
striated muscle of upper (1/3rd) oesophagus

sensory to linings of LOWER pharynx and ALL larynx

Question 18

artery of Ph A 4?

Answer 18

R: brachiocephalic arch
L: arch of aorta

Question 19

skeletal element of Ph A 4 + 6?

Answer 19

cartilages of larynx

Question 20

motor innervation of Ph A 4 (superior laryngeal of vagus)?

Answer 20

cricothyroid
levator palantini
constrictors of pharynx

Question 21

motor innervation of Ph A 6?

Answer 21

intrinsic muscles of larynx (speech)

Question 22

artery of Ph A 6?

Answer 22

pulmonary arch (lungs)

Question 23

how many pharyngeal pouches are there?

Answer 23

4 pairs

epithelial endoderm lining gives rise to structures

Question 24

what does Ph 1 pouch become?

Answer 24

eustachian tube + middle ear
lining of tympanic cavity (middle ear) becomes tympanic membrane
cartilage bars of Ph A 1 + 2 form ossicles

Question 25

what does Ph 2 pouch become?

Answer 25

proliferates and is colonised by lymphatic precursors forming:
palatine tonsils

Question 26

Ph 3 pouch derivatives?

Answer 26

inferior parathyroid

thymus (nodes develop individually on each side and fuse together in middle to form a single gland)

Question 27

Ph 4 pouch derivatives?

Answer 27

superior parathyroid glands
C cells of thyroid (secrete PTH, regulate Ca2+)

(thyroid develops as single gland and bifurcates during descent)