Dev. of Face, Nose, Palate and Tongue

Question 1

name the cartilagenous neurocranium parts

Answer 1

endochondrial ossification

• chondrocranium: base of skull
  
  • occipital base
  • sphenoid body
    
    • hypophyseal cartilage forms around developing pituitary and fuses
  • ethmoid bone
  • lesser wing of sphenoid

Question 2

name the membranous neurocranium parts

Answer 2

• calvaria (cranial vault)
  
  • intramembranous ossification of the mesenchyme at sides and top of brain

Question 3

name the cartilagenous parts of viscerocranium

Answer 3

• forms from the cartilagenous skeleton of the 1st and 2nd pharyngeal arches
  
  • 1st arch dorsal
    
    • malleus and incus
  • 2nd arch dorsal
    
    • stapes and styloid process

Question 4

name the membranous parts of viscerocranium

Answer 4

• intramembranous ossification in the maxillary prominences of the 1st arch
• forms the squamous temporal, maxillary and zygomatic bones
• mandibular prominence forms the mandible

Question 5

name the derivatives of the prominences

Answer 5

• frontonasal
  
  • forehead, external nose, philtrum of upper lip, primary plate
• maxillary
  
  • maxilla, secondary plate, upper cheeck, upper lip (not philtrum)
• mandibular
  
  • mandible, lower cheek, lower lip

Question 6

describe the nasal prominences

Answer 6

• medial nasal prominence
  
  • upper parts of medial prominences migrate medially and eventually fuse to form the nasal septum
  • lower parts of fuse as intermaxillary segment which then fuse with maxillary prominence to form philtrum
• lateral nasal prominence
  
  • form sides of nose
  • fuse with maxillary prominences at nasolacrimal groove

Question 7

describe the intermaxillary segment

Answer 7

• formed by fusion of the medial nasal prominences
• forms:
  
  • deep middle part of the upper lip (covered by extension of maxillary prominence to produce philtrum)
  • primary palate
  • premaxillary part of maxilla and associated gigiva

Question 8

describe the muscle derivatives of the 1st arch

Answer 8

muscles of mastication

Question 9

describe the muscle derivatives of the 2nd arch

Answer 9

muscles of facial expression

Question 10

the muscles of the tongue form from _____ that migrate from ____ ____

Answer 10

the muscles of the tongue form from myoblasts that migrate from occipital somites

Question 11

describe ankyloglossia

Answer 11

“tongue-tied”, where there is a short frenulum that extends to the tip of the tongue

interferes with protrusion of the tongue and may make feeding difficult

Question 12

describe the development of the primary palate and secondary palate

Answer 12

• primary palate
  
  • deep part of intermaxillary segment
  • bone formed by membranous ossification
  • fuses with secondary palate at incisive foramen
  • adult: premaxilla and small part of hard palate
• secondary palate
  
  • lateral palatine processes from internal part of maxillary prominences
  • bone extends from primary palate into palatine processes
  • fuses with primary palate at incisive foramen
  • adult: majority of hard palate, soft palate

Question 13

describe the 2 types of clefts

Answer 13

• anterior:
  
  • cleft lip, cleft of the alveolar part of hard palate
• posterior
  
  • cleft of the secondary part of hard palate, soft palate

Question 14

describe what causes a median cleft lip

Answer 14

• medial nasal prominences fail to fully fuse and form the intermaxillary segment

Question 15

describe what causes a unilateral cleft lip

Answer 15

maxillary prominences failes to fuse with intermaxillary segment

Question 16

describe what causes a bilateral cleft lip

Answer 16

bothy maxillary prominences fail to fuse with the intermaxillary segment

Question 17

describe what causes an oblique facial cleft

Answer 17

maxillary prominence fails to fuse with the lateral nasal prominence so the nasolacrimal duct is open to the surface