PHARYNGEAL ARCH 1

Question 1

when

Answer 1

4th week

Question 2

appearance

Answer 2

fish due to pharyngeal arch

Question 3

PA appears in

Answer 3

cranial chordal sequence

Question 4

origin

Answer 4

1. stomodeum is lined by ectoderm
2. P gut forms the anterior part
3. oropharyngeal membrane raptures
4. cavity within the stomodeum will become confluent with the P gut.
5. ectoderm of the stomodeum will become continuous with the endoderm of the P gut forming a common mucous membrane surrounded by mesoderm from lateral plate mesoderm
6. P gut has a common mucous membrane which forms P pouch
7. mesoderm of the common mucous membrane is populated by neural crest cells which means its mesenchymal cells are neural crest-derived.
8. the mesenchymal cell arrange themselves to become pharyngeal arches.

Question 5

stomodeum is the future

Answer 5

oral cavity

Question 6

how many P arch

Answer 6

6

Question 7

5th P arch

Answer 7

it is rudimentary, forms for a short period

Question 8

each P arch consists of

Answer 8

a core of mesoderm, ectoderm and endoderm

Question 9

P arch are separated from each other by

Answer 9

1. P clefts outside/groove

2. P pouches inside

Question 10

mesoderm forms the core of

Answer 10

P arch

Question 11

mesenchyme in each P arch will condense to form cartilage known as

Answer 11

P arch cartilage

Question 12

mesenchyme cells will differentiate to form

Answer 12

aortic arch artery/ P arch artery

Question 13

some mesenchyme will differentiate into

Answer 13

striated muscles

Question 14

mixed nerve consists of a motor and sensory component

Answer 14

true

Question 15

motor component

Answer 15

supply striated muscles

Question 16

sensory component

Answer 16

branches into

1. pre-trematic branch which goes to the preceding P arch to supply its chordal aspect
2. post-trematic branch will run with the motor component and supply the cranial aspect of that P arch

Question 17

1st P arch

Answer 17

1. Consists of the maxillary process (dorsal) and a ventral mandibular process
2. Mandibular prominence contains Meckel’s cartilage
   Meckel’s cartilage forms incus and malleus of the ear
3. The maxillary prominence gives rise to premaxilla, maxilla, zygomatic bone, and part of the temporal bone
4. Muscles include muscles of mastication, anterior belly of digastric, mylohyoid, tensor tympani, and tensor palatine
5. Muscle innervation is by the mandibular branch of the trigeminal nerve (cranial nerve of the first pharyngeal arch)
6. Primitive maxillary artery

Question 18

2nd P arch

Answer 18

1. Contains cartilage (of the Hyoid arch)
2. This cartilage gives rise to stapes, styloid process of the temporal bone, stylohyoid ligament, the lesser horn, and upper part of the body of the hyoid bone
3. Muscles include the stapedius, stylohyoid, posterior belly of the digastric, auricular, and muscles of facial expression
4. These muscles are supplied by the facial nerve
5. Stapedial artery

Question 19

3rd P arch

Answer 19

1. cartilage will Produce lower part of the body of the hyoid bone and Contributes to the mucosa of the posterior third of the tongue
2. Stylopharengeus muscles
3. The muscles are innervated by the glossopharyngeal nerve
4. Internal carotid artery

Question 20

4th and 6th P arch

Answer 20

1. Cartilage components fuse to form the thyroid, cricoid, arytenoids, corniculate, and cuneiform cartilages of the larynx
2. Muscles (cricothyroid, levator palatine, constrictors of the pharynx) are innervated by the superior laryngeal branch of the vagus (superior part of the accessory nerve).
3. Intrinsic muscles of the larynx are supplied by the recurrent laryngeal branch of the vagus (superior part of the accessory nerve)
4. 4th P arch
   Left: aortic arch
   Right: proximal part of the right subclavian
5. 6TH P arch
   Pulmonary arteries
   Ductus arteriosus