Maxilla & Mandible

• What are the three main parts of the skull?

  The cranial vault, cranial base, and face
• What does the cartilaginous cranial base represent anteriorly?

  The nasal capsule
• What do the terminal parts of the first and second arch cartilages become?

  Ear ossicles
• What process does the cartilaginous base undergo?

  Endochondral ossification
• What type of bone forms the cranial vault and face?

  Membranous bone
• From which pharyngeal arch do the mandible and maxilla form?

  The first pharyngeal arch
• What does Meckel’s cartilage form in primitive vertebrates?

  The lower jaw
• At what stage of development does Meckel’s cartilage extend as a solid hyaline cartilaginous rod?

  At 6 weeks of development
• How does the mandibular branch of the trigeminal nerve relate to Meckel’s cartilage?

  It has a close relationship along its length
• What forms the first bone of the mandible during embryonic development?

  A condensation of mesenchyme
• What is the first site of osteogenesis in the mandible?

  The black dot
• What does the trough formed during ossification consist of?

  Lateral and medial plates
• What does the canal formed during ossification contain?

  The inferior alveolar nerve
• What happens to the teeth as bone forms over the tooth germ?

  They occupy individual compartments
• How does the ramus of the mandible develop?

  By rapid spread of ossification posteriorly
• What does the most posterior extremity of Meckel’s cartilage form?

  The malleus and incus of the middle ear
• What persists as the sphenomandibular ligament?

  The fibrocellular capsule
• What are the three secondary cartilages that assist in the growth of the mandible?

  Condylar, coronoid, and symphyseal cartilages
• When does the condylar process develop?

  At about the tenth week
• What happens to the cone-shaped cartilage of the condylar process?

  It is replaced by bone
• When do the symphyseal cartilages appear?

  In the connective tissue between Meckel's cartilage ends
• What happens to the symphyseal cartilages after birth?

  They are obliterated within the first year
• How does the mandible develop in relation to Meckel’s cartilage?

  It is almost entirely independent of it
• What is the maxilla developed from?

  A center of ossification in mesenchyme
• Where does the center of ossification for the maxilla appear?

  In the maxillary process of the first arch
• What does the maxillary sinus develop from?

  A pocketing of the mucosa of the middle meatus
• When does the maxillary sinus appear?

  At the 16th week of intrauterine life
• What happens to the maxillary sinus after birth?

  It enlarges along with the maxilla
• What are the common features of mandible-maxilla development?

  • Begin from a single center of membranous ossification
  • Related to a nerve and primary cartilage
  • Form a neural element related to the nerve
  • Develop an alveolar element related to developing teeth
  • Develop secondary cartilages to assist in growth
• What is the body to ramus ratio at birth?

  Higher than in adulthood
• What happens to the gonial angle from birth to adulthood?

  It decreases
• What is the effect of damage to the condylar cartilage?

  It can affect chin prominence
• How does the mandible grow to make space for permanent teeth?

  By downward and forward growth
• What happens to the deciduous dentition at 4 years of age?

  It is fully complete
• What occurs between the anterior deciduous teeth around 5 years of age?

  Spaces are normally seen between them
• Why is crowding of lower anterior teeth common?

  Due to lack of midline growth site
• What is the role of the alveolar process in the mandible?

  It is influenced by the dentition
• What is the significance of the growth of the mandible?

  It accommodates the eruption of permanent teeth
• What happens to the symphysial cartilage after the first year of life?

  It is replaced by bone
• How does the maxilla develop in relation to the nasal capsule?

  It is closely associated with it