Embryonic Orofacial Development

Stomodeum source

ectodermal depression enlarged by the disintegration of the oropharyngeal membrane

Mandibular arch source

fused mandibular processes and neural crest cells

Maxillar processes

develops superiorly and anteriorly around the stomodeum

Maxillary processes source

superior and anterior swelling from the mandibular arch and neural crest cells

Frontonasal process

forms as a bulge of tissue at the most cephalic end of the embryo

Frontonasal process source

ectodermal tissue and neural crest cells

Medial nasal processes

the middle part of tissue growing around the nasal placodes appears as 2 crescent-shaped swellings located between the nasal pit

Medial nasal processes source

frontonasal process and medial nasal pits

Lateral Nasal processes

located on the outer part of the nasal pit

Lateral nasal process source

frontonasal process and lateral nasal pit

Intermaxillary Segment

is involved in the formation of the maxillary teeth and structures such as the primary palate and nasal septum

First (Mandibular) Arch Nerve

CN 5 Trigeminal

First (Mandibular) Arch Muscle

Muscle of mastication

Mylohyoid

Ant. Belly of the digastric

First (Mandibular) Arch Skeletal Structures

Mandible and Teeth

Middle Ear

Second (Hyoid) Arch Nerve

CN 7 Facial

Second (Hyoid) Arch Muscle

Muscle of facial expression

Post. Belly of the digastric

Stylohyoid

Second (Hyoid) Arch Skeletal Structure

Hyoid bone

Styloid process

Middle ear

Third Arch Nerve

CN 9 Glossopharyngeal

Third Arch Muscle

Stylopharyngeal Muscle

Third Arch Skeletal Structures

Body of the hyoid bone

Fourth-Sixth Arches Nerve

CN 10 Vagus

Fourth-Sixth Arches Muscle

Palatal muscle

Fourth-Sixth Arches Skeletal region

Larynx region

Which of the following structures is NOT derived embryonically from the 1st branchial/pharyngeal arch?

hyoid bone

Which of the following develops from the ectoderm?

epithelial tissue

The oropharyngeal membrane forms at the caudal end of the embryonic disc. This membrane is the location of the future primitive mouth.

first statement is false; second statement is true

The 1st pharyngeal groove forms the

external acoustic meatus

Cranial nerve VII (facial nerve) develops from the 1st branchial/pharyngeal arch.

False

The forehead and bridge of the nose forms from the:

frontonasal process

The maxillary process on each side of the developing face fuses with the ______ on each side to create the labial commissure.

mandibular process

The anterior two-thirds of the tongue develops from two lateral lingual swellings and a midline tuberculum impar. These are both from the 3rd branchial/pharyngeal arch.

first statement is true; second statement is false

Merging or Apparent Fusion

Elimination of a groove between 2 swellings of tissue on the SAME structure

True or Actual Fusion

Union of structures, which are entirely separate from one another

Palatal Development 5th to 6th Week

Primary palate: intermaxillary segment from fused medial nasal processes

Palatal Development 6th to 12th week

Secondary Palatal: Fused palatal shelves from maxillary processes

Mandibular arch

Fused mandibular processes

The eyes of an embryo develop from

lens placodes

The embryonic period occurs during the first week after conception.

False

The developmental process that sees a change in identical embryonic cells to become distinct structurally and functionally is:

differentiation

The face and neck begin to form during the _________ week of prenatal development.

4th

A teratogen is defined as

environmental factors or agents causing malformations

Which clinical structure marks the fusion of the copula of the tongue base with the anterior swellings of the tongue body during the 8th week

sulcus terminalis

The fusion of all three palatal processes to form the final palate is completed during the _______ week of prenatal development.

12th

Stomodeum

primitive mouth

Palatal Development 12th week

Final palate: Fusion of all three processes

Cleft Palate

Failure of fusion of the palatal shelves with the primary palate and/or with each other

Cleft Uvula

least complicated form of cleft palate

Epstein Pearl

small white cysts on hard palate of newborn common, disappear in few weeks

Tongue Development

develops during the 4th through 8th week of prenatal development

The body of the tongue develops from the:

first branchial arch

Base of tongue develops from the:

2nd - 4th branchial arch

Body of tongue Formation

1) begins are a triangular medial swelling, the tuberculum impar

2) 2 oval swells develop on each side of the tuberculum impar- lateral lingual swelling (will grow and merge with each other)

3) lateral lingual swelling overgrow and encompass the disappearing tuberculum impar

4) this forms the anterior 2/3 of mature tongue

5) copulas is found at midline and overgrows hyoid arch and forms posterior 1/3 of mature tongue

6) 8th week, anterior swelling merge with copula of base

7) this fusion is sulcus terminalis

1st Pharyngeal Pouches

tympanic membrane, tympanic cavity

When do the maxillary process and nasal process fuse? (upper lip)

6th and 7th week

Ectoderm Origin

Epiblast layer

Mesoderm Orgin

Migrating cells from epiblast layer

Endoderm Origin

Migrating cells from epiblast layer

Neural Crest Cell Origin

Migrating neuroectoderm

Ectoderm future structure

Epidermis

Mesoderm future structure

Dermis, muscle, bone, lymphatics, blood cells, bone marrow, etc

Endoderm future structures

respiratory and digestive system linings, liver and pancreatic cells

Neural Crest Cells future structure

Components of the nervous system and certain dental tissue

mandibular symphysis

anterior median depression indicating point of mandibular fusion

Intermaxillary segment future structures

Maxillary incisors, primary palate, nasal septum

Reichert's cartilage

Cartilage in second branchial arch that eventually disappears.

Which palate acts as a partial separation between the oral cavity proper and the nasal cavity?

Primary palate

median palatine raphe

ridge of soft tissue indicating the line of fusion of palatal shelves at the median palatine suture

What is a copula?

base of the tongue

What is the beginning of the thyroglossal duct?

Foramen cecum

What duct shows the origin of the thyroid gland?

Thyroglossal duct

Ankyloglossia

short attachment of lingual frenulum

preimplantation (1st week)

Fertilization and implantation

embryonic period (2nd to 8th week)

Induction, proliferation, differentiation, morphogenesis, maturation

Fetal Period (3rd to 9th month)

Maturation

Induction

action of one group of cells on another that leads to the establishment of the developmental pathway in responding tissue

proliferation

controlled cellular growth

Differentiation

process in which cells become specialized in structure and function

Morphogenesis

Development of specific tissue structure or differing form due to embryonic cell migration or proliferation and inductive interactions

Maturation

Attainment of adult function and size due to proliferation, differentiation, and morphogenesis

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