Development of the Head and Face

Question 1

What is the name of the expanded region at the cranial end of the primitive groove?

What does it do?

Answer 1

primitive node

directs the formation and disappearnce of the primitive groove

Question 2

What happens at the prechordal plate?

What feature of the embryo does this signify?

Answer 2

the epiblast and hypoblast cells have stuck together so that the mesoderm cannot get between

this signifies the cranial portion of the embryo & important signaler for differentiation of the head

Question 3

What is the chordamesoderm?

Answer 3

group of mesoderm that rolls through the primitive node and migrade cranially (mesoderm that will form the notochord)

little tip of chordamesoderm at the tip of the cranial direction that does not differentiate into notochord

Question 4

nondifferentiated chordemesoderm and prechordal plate set signaling for what structure?

How does it do this?

Answer 4

neural tube (head)

1. signaling markers to ectoderm, cauing ectoderm immediately superficial to differentiate (neural ectoderm)
   
   1. neural ectoderm will break free and form neural tube
2. neural tube combines with chordemesoderm and prechordal plate to form the head

Question 5

What is the name of the embryonic forehead?

What is makes up the early mouth?

Answer 5

frontonasal prominence

oropharyngeal membrane

Question 6

Identify the aspects of the early face

Answer 6

Question 7

What fuses to form the lower jaw?

What fuses to form the upper jaw?

Answer 7

lower jaw: mandibular processes

upper jaw: maxillary and nasomedial processes

Question 8

Identify the features of the developing face

Answer 8

Question 9

Where does most of the connective tissue of the face develop from?

Answer 9

most of the connective tissue of the face develops rom neural crest cells and migrates to the area

Question 10

What portion of the face is nerual crest derived?

What portion of the face is mesoderm derived?

Answer 10

nerual crest: ventral

mesoderm: dorsal

Question 11

What three major structures are formed from the first pharyngeal arch?

Answer 11

maxilla, mandible, inner ear ossicles

Question 12

Which muscels are formed from the first pharyngeal arch?

Which muscles are formed from the second pharyngeal arch?

Answer 12

1st: muscles mastication
2nd: muscles of facial expression

Question 13

Which cranial nerve is associated with the first pharyngeal arch?

Which cranial nerve is associated with the second pharyngeal arch?

Answer 13

1st: trigeminal
2nd: facial

Question 14

What is the new name once the two medial nasal prominences merge?

What other fusion is necessry for normal development?

Answer 14

the primary palate

fusion of the medial nasal processes and the advancing maxillary processes

Question 15

When the primary process grows dorsally, what does its name change to?

What is the name of the shelf of bone growing out of the medial side of the maxillary?

Together these structures form what?

Answer 15

median palatal process

lateral palatal process

the secondary palate

Question 16

Why does the tongue have such a weird innervation pattern?

Answer 16

It is formed from the first 3 arches

it gets trigeminal from the first (lingual)

facial from the second (chorda tympani)

and glossopharyngeal from the 3rd

Question 17

What is formed from the pharyngeal pouches and clefts?

Answer 17

1. First cleft and pouch
   
   • auditory system
   • external auditory meatus
   • tympanic membrane and tympanim
2. 2nd pouch
   
   • palatine tonsils
3. Rest of pouches
   
   • midline glandular derivatives
     
     • thyroid
     • thymus
     • parathyroid

Question 18

What are the two examples of First Arch problems?

Answer 18

1. Treacher Collins Syndrome
   
   1. autosomal dominant
   2. abnormal mandible and zygomatic development
   3. disruption orbit of the eye, ear, and tongue
2. Pierre Robin Sequence (Syndrome)
   
   1. may be genetic
   2. micrognathia
   3. displaced tongue
   4. cleft palate
   5. obstructed airway

Question 19

What is the outcome if the palates do not fuse medially?

Answer 19

cleft palate

Question 20

check out all these patterns of cleft palate formation

Question 21

What happens when pharyngeal clefts persist?

Answer 21

can see sometimes when infants are succling

instead of disapearing, they can fill with fluid or tissue