Lecture 18: Development of Pharyngeal Arches

Question 1

What are the 3 principle components of the pharyngeal complex?

Answer 1

Pharyngeal arches, clefts, and pouches

Question 2

Name the type of tissue that migrates from the 1st and 2nd pharyngeal arches into the developing face

Answer 2

Neural-crest derived mesenchyme

Question 3

From which embryonic germ layer do muscles develop?

Answer 3

Mesoderm

Question 4

What type of cells give rise to the facial skeleton and coronal and sagittal sutures?

Answer 4

Neural crest cells

Question 5

What gives rise to the posterior neurocranium and basicranium?

Answer 5

Mesoderm

Question 6

Which pharyngeal arch gives rise to Meckel’s cartilage, malleus, incus, mandible, and maxilla?

Answer 6

Pharyngeal arch 1

Question 7

Fusion of which prominences is required for the normal development of the upper lip?

Answer 7

Nasomedial, nasolateral, and maxillary prominences

Question 8

What facial abnormality is the result of failure of the nasomedial and maxillary prominences to fuse?

Answer 8

Cleft lip

Question 9

What is the problem underlying cleft palate?

Answer 9

Problem with nasomedial segments fusing

Question 10

What are the muscular components of pharyngeal arch 1?

Answer 10

Muscles of mastication - temporalis, masseter, mylohyoid, anterior belly of digastric

Question 11

What are the muscular components of pharyngeal arch 2?

Answer 11

Muscles of facial expression - buccinator, orbicularis oris, posterior belly of digastric, platysma, frontalis, orbicularis oculi, occipitalis

Question 12

What are the muscular components of pharyngeal arch 3?

Answer 12

Stylopharyngeus

Question 13

What are the muscular components of pharyngeal arches 4 and 6?

Answer 13

levator veli palatini, pharyngeal muscles, intrinsic muscles of larynx

Question 14

What are the nerve components of pharyngeal arch 1?

Answer 14

Trigeminal nerve (CN V) - specifically mandibular division (V3)

Question 15

What are the nerve components of pharyngeal arch 2?

Answer 15

Facial nerve (CN VII)

Question 16

What are the nerve components of pharyngeal arch 3?

Answer 16

Glossopharyngeal nerve (CN IX)

Question 17

What are the nerve components of pharyngeal arches 4 and 6?

Answer 17

Vagus nerve (CN X)

Question 18

What structures does the frontonasal prominence form?

Answer 18

forehead, bridge of nose, medial/lateral nasal prominences

Question 19

What structures does the maxillary prominence form?

Answer 19

cheeks, lateral portion of upper lip

Question 20

What structures does the medial nasal prominence form?

Answer 20

Philtrum of upper lip, crest/tip of nose

Question 21

What structures does the lateral nasal prominence form?

Answer 21

Alae of nose

Question 22

What structures does the mandibular prominence form?

Answer 22

Lower lip

Question 23

When are BMPs expressed and what is their function in development of facial structures?

Answer 23

Early expression; induce superficial location of palatal shelves

Question 24

What is the function of Shh in induction of facial development?

Answer 24

Early induction of facial primordia; medial edge epithelial of palatal shelves (fusion of epithelium)

Question 25

What is the function of Tbx22 in facial development?

Answer 25

Ensures mobility of tongue and allows tongue to move and make way for palatal shelf fusion

Question 26

Ankyloglossia

Answer 26

Mutations in Tbx22 - immobile tongue

Question 27

Median cleft lip

Answer 27

Incomplete merging of two medial nasal prominences; leads to forms of bifid nose

Question 28

What is the primary feature of a complete bilateral cleft palate?

Answer 28

Premaxilla is unattached, grows forward

Question 29

Macrostonia

Answer 29

"Large mouth"; hypoplasia or incomplete fusion of maxillary and mandibular prominences

Question 30

Treacher-Collins Syndrome, Pierre Robins Syndrome

Answer 30

Classic arch 1 abnormalities; deficiency in formation of facial skeleton

Question 31

Which pharyngeal arch gives rise to Reichert's cartilage, stapes, styloid process, lesser horns and superior portion of hyoid bone?

Answer 31

Pharyngeal arch 2

Question 32

Which pharyngeal arch gives rise to greater horns and inferior portion of hyoid bone?

Answer 32

Pharyngeal arch 3

Question 33

Which pharyngeal arch gives rise to the laryngeal cartilages?

Answer 33

Pharyngeal arches 4 and 6

Question 34

Which aortic arch contributes to maxillary arteries?

Answer 34

Aortic arch I

Question 35

Which aortic arch produces stapedial and hyoid arteries?

Answer 35

Aortic arch II

Question 36

Which aortic arch contributes to common carotid arteries and internal carotid arteries?

Answer 36

Aortic arch III

Question 37

Which pharyngeal cleft is the external auditory meatus derived from?

Answer 37

Pharyngeal cleft I

Question 38

Which pharyngeal cleft is the neck derived from?

Answer 38

Pharyngeal cleft II, III, and IV

Question 39

Which aortic arch gives rise to the right subclavian artery and aorta?

Answer 39

Aortic arch IV

Question 40

Which pharyngeal pouch is the middle ear and auditory tube derived from?

Answer 40

Pharyngeal pouch I

Question 41

Which pharyngeal pouch is the supra-tonsillar fossa derived from?

Answer 41

Pharyngeal pouch II

Question 42

Which pharyngeal pouch is the thymus and parathyroid gland derived from?

Answer 42

Pharyngeal pouch III

Question 43

Which pharyngeal pouch is the thymus, parathyroid gland, ultimobranchial body formed from?

Answer 43

Pharyngeal pouch IV (and V)

Question 44

Cervical cysts/fistulas

Answer 44

Result of remnants of pharyngeal clefts 2-4 along border of sternocleidomastoid muscle

Question 45

DiGeorge Syndrome

Answer 45

Group of disorders which share a common microdeletion on chromosome 22. Characterized by hyoparathyroidism, hypocalcemia, underdeveloped/absent thymus, heart defects; may also involve delays in speech/learning development

Question 46

From which pharyngeal arches does the tongue arise?

Answer 46

Pharyngeal arches 1, 2, and 3

Question 47

Sulcus terminalis of tongue

Answer 47

Site of union between the base and body of the tongue, delineated by V-shaped groove

Question 48

Name the sensory and taste bud innervations of the anterior 2/3 of the tongue

Answer 48

Sensory: lingual nerve (branch of trigeminal) | Taste buds: facial nerve (chorda tympani)

Question 49

Name the sensory and taste bud innervations of the posterior 1/3 of the tongue

Answer 49

Sensory: glossopharyngeal nerve (CN IX) | Taste buds: glossopharyngeal nerve, vagus nerve

Question 50

From what structure does the thyroid originate?

Answer 50

Thyroid diverticulum

Question 51

Ectopic thyroid tissue

Answer 51

Anomaly in thyroid development where thyroid tissue is present along the course of thyroglossal duct

Question 52

Thyroglossal duct fistula

Answer 52

Rupturing of a thyroglossal duct cyst presenting as a draining sinus