Pharyngeal Arches B&B

Question 1

what are the three components of the pharyngeal apparatuses?

Answer 1

1. Pharyngeal arches - bilateral mounds
2. pharyngeal clefts - invaginations between the mounds (arches), outside of embryo made of ectoderm
3. Pharyngeal pouches - depressions between the mounds (arches), inside of embryo made of endoderm

Question 2

What is contained in each of the pharyngeal arches? (3)

Answer 2

1. Core of mesenchyme connective tissue that gives rise to cartilage/bones and muscles.
2. Neural crest cells which migrate to the center and give rise to cranial nerves.
3. An artery which forms the aortic arches.

Question 3

What are the bones of the first pharyngeal arch?

Answer 3

1. maxillary process —> maxilla, zygomatic bone
2. mandibular process —> mandible, Meckel’s cartilage (becomes incus and malleus in adults)

Question 4

what does embryonic Meckel’s cartilage become in adults? from which pharyngeal arch is it derived?

Answer 4

first pharyngeal arch (part of mandibular process), becomes incus and malleus (inner ear) in adults

Question 5

What are the muscles of the first pharyngeal arch?

Answer 5

muscles of mastication (this makes sense because the mandible develops from the first arch!)

1. temporalis (on temporal skull)
2. pterygoids (side of jaw)
3. masseter (side of jaw)
4. mylohyoid (connects mandible to hyoid)
5. anterior digastric (below jaw)
6. tensor tympani (ear)
7. anterior 2/3 of tongue

Question 6

which cranial nerves are derived from the first pharyngeal arch?

Answer 6

mandibular and maxillary divisions of the trigeminal nerve (this makes sense because the mandible/maxilla are derived from the first arch!)

sensory to face + motor to muscle of mastication (which also derive from first arch! woah!)

Question 7

what blood vessel derives from the first pharyngeal arch?

Answer 7

maxillary artery

this makes sense because maxilla/mandible/muscles of mastication all derive from first arch!

Question 8

Which bones are derived from the second pharyngeal arch? (3)

Answer 8

“Reichert’s cartilage” becomes:
1. stapes (ear)
2. styloid process of temporal bone
3. lesser horn of hyoid

Question 9

from which pharyngeal arch is Reichert’s cartilage derived and what does it become? (3)

Answer 9

second pharyngeal arch, becomes:
1. stapes (ear)
2. styloid process of temporal bone
3. lesser horn of hyoid

Question 10

What are the muscles of the second pharyngeal arch?

Answer 10

1. muscles of facial expression
2. stapedius (ear)
3. auricular muscles (ear)
4. stylohoid
5. posterior digastric (under jaw)

Question 11

which nerve is associated with the second pharyngeal arch?

Answer 11

facial nerve which makes sense because the muscles of facial expression derive from the second arch!!

Question 12

Which arteries are associated with the second pharyngeal arch?

Answer 12

1. stapedial artery - embryonic vessel, involutes in development
2. hyoid artery - embryonic vessel, develops into small branch of internal carotid

Question 13

which bone, muscle, nerve, and artery are associated with the third pharyngeal nerve?

Answer 13

bone: hyoid (body and greater horn)
muscle: stylopharyngeus (connects styloid process to pharynx)
nerve: glossopharyngeal (IX) (mixed)
arteries: common carotid + proximal internal carotid

Question 14

from which pharyngeal arch does the common carotid artery derive?

Answer 14

Third pharyngeal arch

Question 15

which pharyngeal arch does not persistent humans?

Answer 15

Fifth pharyngeal arch

Question 16

Which nerve innervates both the fourth and sixth pharyngeal arches?

Answer 16

vagus nerve

4th: superior laryngeal branch
6th: recurrent laryngeal branch (loops around aorta)

Question 17

what cartilage develops from the 4th and 6th pharyngeal arches?

Answer 17

both arches fuse to form larynx cartilage - thyroid, cricoid, arytenoid, corniculate, cuneiform

Question 18

what muscles develops from the 4th and 6th pharyngeal arches?

Answer 18

laryngeal muscles (this makes sense because the larynx cartilage also derives from these arches!)

4th: cricothyroid, levator palatini, pharyngeal constrictors
6th: intrinsic muscles of larynx (besides cricothyroid)

Question 19

which arteries are derived from the 4th and 6th pharyngeal arches?

Answer 19

4th: aortic arch (left) + proximal right subclavian artery (right)

6th (“pulmonary arch”): proximal pulmonary artery (right/left) + ductus arteriosus (left)

Question 20

from which pharyngeal arch does the aortic arch derive?

Answer 20

4th pharyngeal arch (left)

on the right, becomes proximal right subclavian artery

Question 21

from which pharyngeal arch does the right subclavian artery derive?

Answer 21

4th pharyngeal arch (right)

on the left, becomes aortic arch

Question 22

from which pharyngeal arch does the proximal pulmonary arteries and ductus arteriosus derive?

Answer 22

6th pharyngeal arch - “pulmonary arch”

Question 23

from which pharyngeal arch are the following nerves derived?
a. facial
b. trigeminal
c. vagus
d. glossopharyngeal

Answer 23

1st: trigeminal (CN V, 5)
2nd: facial (CN VII, 7)
3rd: glossopharyngeal (CN IX, 9)
4th/6th: vagus (CN X, 10)

Question 24

which nerves develop from the following pharyngeal arches?
1st
2nd
3rd
4th/6th

Answer 24

1st: trigeminal (CN V, 5)
2nd: facial (CN VII, 7)
3rd: glossopharyngeal (CN IX, 9)
4th/6th: vagus (CN X, 10)

Question 25

which structures (on a large scale) are associated with the 1st, 2nd, 3rd, and 4th/6th pharyngeal arches?

Answer 25

1st —> maxilla/ mandible
2nd —> hyoid
3rd —> hyoid
4th/6th —> larynx

Question 26

from which pharyngeal arches are the following arteries derived?
a. common/internal carotid
b. aortic arch (left)
c. ductus arteriosus/ pulmonary artery

Answer 26

a. common/internal carotid - 3rd pharyngeal arch
b. aortic arch (left) - 4th pharyngeal arch
c. ductus arteriosus/ pulmonary artery - 6th pharyngeal arch

Question 27

Treacher Collins Syndrome

Answer 27

failure of neural crest cell migration to first pharyngeal arch

underdeveloped facial bones (mandibular hypoplasia, micrognathia, absent/small ears, glossoptosis)

may lead to difficulty breathing due to airway obstruction by tongue

Question 28

baby with abnormal facial features struggling to breath may have an abnormally developed _____ pharyngeal arch

Answer 28

first pharyngeal arch —> Treacher Collins Syndrome

underdeveloped facial bones (mandibular hypoplasia, micrognathia, absent/small ears, glossoptosis)

may lead to difficulty breathing due to airway obstruction by tongue

Question 29

from which pharyngeal arches does the tongue and it’s innervation derive?

Answer 29

anterior 2/3: 1st/2nd arches, sensation via CN V (trigeminal, 1st arch), taste via CN VII (facial, 2nd arch)

posterior 1/3: 3rd/4th arches, sensory via CN IX (glossopharyngeal, 3rd arch), taste via CN X (vagus, 4th arch)

motor: CN XII (hypoglossal) with tiny bit from CN X