Development of Growth and Jaw

Question 1

what are the head and neck formed from?

Answer 1

the frontal prominence and branchial arches.

Question 2

what is the lower jaw formed from?

Answer 2

the first branchial arch / mandibular branch

Question 3

what is the maxillary developed formed from?

Answer 3

develop from the mandibular process

Question 4

what is the branchial arch?

Answer 4

growth and lateral extension of mesoderm in the head and neck region of the developing vertebrae embryo.

Question 5

what cells is the branchial arch developed from?

Answer 5

the cranial neurocrest cells, which form the ectomesenchymal cells.

Question 6

what does the branchial arch form?

Answer 6

jaw, middle ear and specialised structures in the head and neck.

Question 7

how does the face begin to develop?

Answer 7

frontal and frontonasal/medial nasal processes develop from the frontal prominence. Process characterized by proliferation and migration of ectomesenchymal cells -> induce localised thickening of mesenchyme.

Question 8

What 3 features are present in a 6/7 week old embryo?

Answer 8

Lateral nasal process, medial nasal process, maxillary process.

Question 9

When does palatogenesis occur?

Answer 9

6-8 weeks

Question 10

What is palatogenesis?

Answer 10

Formation of a secondary/ definite palate. 3 outgrowths in oronasal cavity - nasal septum and 2 palatine processes.

Question 11

During the 6th week of intrauterine life, what is present?

Answer 11

Primary palate, primary nasal cavities, primary nasal septum.

Question 12

How does the nasal septum develop?

Answer 12

Downward growth from the frontonasal process along the midline. Primary palate also formed from extension of frontonasal processes.

Question 13

How do the 2 palatine processes develop?

Answer 13

Extend from maxillary processes downward and vertically on each side of tongue. Behind primary palate.

Question 14

How does palatogenesis occur?

Answer 14

Primary nasal septum develops by downard growth from frontonasal processes down midline. Primary palate also formed. (6 weeks) 2 palatine processes extend from maxillary processes downward and vertically on each side of tongue (7 weeks). Tongue drops. Palatal processes elevate above tongue. Horizontal growth. Fuse along midline and primary palate. Converge with nasal septum Forms secondary palate and separates primary oral cavity into oral and nasal. (8 weeks)

Question 15

When is palatal fusion complete by?

Answer 15

Week 12.

Question 16

What is mandible formed from?

Answer 16

Band of Meckel’s cartilage

Question 17

Describe mandible development.

Answer 17

Mandible appears from band of Meckel’s cartilage. Bone develops intramembraneously. Ossification centre forms (7th week) and bone spreads rapidly backwards, forwards and upwards. Bone on lateral side spreads (future body of mandible). Mandible extends towards midline, separated by fibrous mandibular symphysis.
Upward extension of lateral and medial plates of bone above and around nerve canals forming alveolar bone development. 3 Secondary growth cartilages form via endochondral bone formation between 10th and 14th weeks.

Question 18

What is Meckel cartilage formed from?

Answer 18

From 1st pharyngeal arch.

Question 19

What is the proximal end of Meckel’s cartilage connected to?

Answer 19

Ear capsules, which form the ossicles of middle ear and ligaments.

Question 20

What is the centre of primary ossification located close to?

Answer 20

To division of inferior alveolar branch nerve (incisive and mental branch)

Question 21

Describe intramembranous bone formation?

Answer 21

Bone formed directly within mesenchyme. Condensation of vascularised mesenchyme. Mesenchyme osteoprogenitor cells lead to osteoblast differentiation. Bone matrix formation and development of bone spicules called trabeculae. Surrounding periosteum leads to appositional bone growth. Does not directly involve cartilage. Developed directly from condensed mesenchyme.

Question 22

What are remnants of Meckel’s cartilage formed into?

Answer 22

Ear ossicles and sphenomandibular and disco-malleolar ligaments.

Question 23

What are teeth separated by?

Answer 23

Interdental septa.

Question 24

How does the maxilla develop?

Answer 24

Develops intramembraneously. (Week 6-7). Develops in maxillary process. Ossification centre is in a band of tissue outside nasal capsule between alveolar and infra-orbital nerves. Spreads backwards to developing zygomatic processes, forward to future incisor region, upwards to form frontal-nasal processes and downards to form alveolar processes.

Question 25

How does the maxilla form the hard palate?

Answer 25

Ossification during development of maxilla extends into palatal process. Medial and lateral alveolar plates develop.

Question 26

How does the premaxilla form?

Answer 26

Derived from fronto/medial nasal processes.

Question 27

What is the premaxilla?

Answer 27

Pair of bony structures at median anterior part of the maxillary. Incisor bearing part of maxilla.

Question 28

Which branch do the mandible and maxilla develop from

Answer 28

First branchial arch.

Question 29

What is a suture?

Answer 29

Dense, connective fibrous tissue joint between flat bones, limits movement. Connects two periosteal bone surfaces.

Question 30

How does growth of mandible occur?

Answer 30

Bone deposition on posterior surface of ramus and coronoid process with resorption on anterior surface. Ramus relocates backwards. Displacement movement downward and forward.

Question 31

How does the mandible increase in height?

Answer 31

By condylar and condyloid growth, siigmoid notch and increase of alveolar bone.

Question 32

How does the mandible increase in width?

Answer 32

At mandibular symphysis, by condylar growth, deposition of bone on outer surface of ramus and resorption on inner surface.

Question 33

How does growth of maxilla occur?

Answer 33

Growth vertically in fronto-maxillary sutures. Downward growth allows vertical drift of teeth. Bone deposition on oral side, resorption on nasal surface.

Question 34

How does maxilla have increased growth of height?

Answer 34

Via development of alveolar process.

Question 35

How does the maxilla increase in width?

Answer 35

Growth of palatal suture and zygomatico-maxillary sutures.

Question 36

What is the cambian layer?

Answer 36

Inner osteogenic later of periosteum that extends along the suture bone margins which allows for bone apposition.

Question 37

What are the further features of jaw development and growth?

Answer 37

Tooth development, alveolar bone development, neuro and vascular bundles and muscle development and attachment.