Page 1: Development of Orofacial Structures

Overview

• Focus on the development of orofacial structures.

• Development occurs from the fourth to twelfth weeks of prenatal development.

Page 2: Orofacial Development

Timeline

• Structures develop during the later embryonic and early fetal periods.

• Continues from previous chapter on stomodeum, face, and neck development.

Page 3: Development of Orofacial Structures

Focus on Palatal Development

Page 4: Palatal Development: Time Table

Key Stages

• Fifth week: Formation starts.

• Primary palate from embryonic structures.

• Completion of palate by the twelfth week.

Page 5: Palatal Development: Timetable

Weekly Breakdown

• Fifth to Sixth Week: Primary palate from fused medial nasal processes.

• Sixth to Twelfth Week: Secondary palate from fused palatal shelves.

• Twelfth Week: Final palate with fusion of all processes.

Page 6: Palatal Development: Process Overview

Fusion Process

• Involves fusion of tissue from different embryo surfaces, similar to neural tube fusion.

Page 7: Primary Palate Formation

Development

• Formation of intermaxillary segment in the fifth week.

• Serves as a partial separation between oral and nasal cavities.

Page 8: Development of Intermaxillary Segment

Description

• Forms from fused medial nasal processes.

Page 9: Primary Palate Formation

Role of Primary Palate

• Intermaxillary segment also forms the primary palate.

• Acts as partial separation between oral and nasal cavities.

Page 10: Secondary Palate Formation

Starting in the Sixth Week

• Formation of palatal shelves from bilateral maxillary processes.

Page 11: Secondary Palate Formation

Structural Overview

• Components: Lip, Premaxilla, Palatal Shelf.

Page 12: Secondary Palate Formation

Shelf Development

• Shelves grow vertically alongside the developing tongue.

Page 13: Secondary Palate Formation

Tongue's Role

• Tongue fills the nasal and oral cavity; moves to allow shelf fusion.

Page 14: Secondary Palate Formation

Final Steps

• Shelves move into horizontal position and fuse to create secondary palate.

Page 15: Secondary Palate Formation

Final Structure

• Forms posterior two-thirds of hard palate and certain teeth.

Page 16: Secondary Palate Formation

Fusion Indicators

• Median palatine raphe and suture indicate fusion line of palatal shelves.

Page 17: Epstein Pearl

Description

• Small white papule in palate due to trapped epithelial tissue during fusion.

Page 18: Completion of Palate

Fusion Process

• Anterior part of primary palate fuses with secondary palate from back to front.

Page 19: Palatal Development: Time Table 5-1

Summary

• Fifth to Sixth Week: Primary palate forms.

• Sixth to Twelfth Week: Secondary palate develops.

• Twelfth Week: Final palate completed.

Page 20: Developmental Disturbances

Factors

• Cleft palate and associated issues can result from improper fusion.

Page 21: Cleft Palate

Condition Overview

• Results from failure to fuse palatal shelves or primary palate; varying severity.

Page 22: Cleft Palate Overview

Structures Involved

• Lip, primary palate, nasal cavity affected.

Page 23: Cleft Palate Image

Visual Reference

• Figure of cleft palate.

Page 24: Cleft Palate with Cleft Lip

Related Condition

• Description of cleft palate combined with cleft lip.

Page 25: Cleft Uvula

Definition

• Least complicated cleft palate example, also known as bifid uvula.

Page 26: Nasal Cavity and Septum Development

Overview

• Development occurs concurrently with palate formation.

Page 27: Nasal Cavity and Septum Development

Functional Aspect

• Forms part of the respiratory system.

Page 28: Nasal Cavity and Septum Development

Formation Timeline

• Nasal septum develops from fused medial nasal processes during palate formation.

Page 29: Nasal Cavity and Septum Development

Structural Growth

• Nasal septum grows beneath medial nasal processes and the stomodeum.

Page 30: Nasal Cavity and Septum Development

Fusion

• Septum fuses with final palate when it forms.

Page 31: Nasal Cavity Structure Illustration

Key Components

• Related to palatal and nasal structure.

Page 32: Clinical Consideration for Nasal Cavity

Educational Reference

• Source: Illustrated Anatomy of the Head and Neck.

Page 33: Deviated Septum

Description

• Occurs when nasal septum is displaced to one side, affecting nasal cavities.

Page 34: Deviated Septum Image

Visual Reference

• Illustration of a deviated septum.

Page 35: Tongue Development

Overview

• Tongue develops from the fourth to eighth weeks of prenatal development.

Page 36: Tongue Development Timeline

Key Structures

• Body: Tuberculum impar and lateral lingual swellings.

• Base: Copula overgrowing second branchial arches by the eighth week.

Page 37: Body of Tongue Development

Initial Formation

• Begins as a triangular median swelling in the primitive pharynx.

Page 38: Tongue Development

Positioning

• Tuberculum impar in midline of embryo's nasal and oral cavities.

Page 39: Body of Tongue Development

Lateral Growth

• Two lateral lingual swellings develop and merge to form the tongue's body.

Page 40: Body of Tongue Development

Structure Formation

• Two fused swellings encompass the tuberculum impar forming the anterior two-thirds of the tongue.

Page 41: Body of Tongue Development

Median Lingual Sulcus

• Marks fusion line of lateral swellings and deeper fibrous structure.

Page 42: Base of Tongue Formation

Posterior Development

• Copula overgrows the second branchial arch to form base of the tongue.

Page 43: Base of Tongue Formation

Additional Structure

• Epiglottic swelling appears posterior to the copula.

Page 44: Completion of Tongue Formation

Fusion Process

• Copula merges with anterior swellings forming the complete tongue.

Page 45: Completion of Tongue Formation

Sulcus Terminalis

• Marks the border between the base and body of the tongue.

Page 46: Development of Tongue Timeline

Summary of Events

• Fourth to eighth week: Initial tongue structures develop; completed by the eighth week.

Page 47: Developmental Disturbances: Tongue

Overview

• Ankyloglossia described as “tongue-tied,” due to a short lingual frenum.