Development of Orofacial Structures Flashcards by Staci Thomas

The cranium is derived from two parts, which are…

Neurocranium

Viscerocranium

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The Neurocranium and Viscerocranium are developed from what embryological layer?

Mesenchyme

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This part of the cranium gives rise to bones that enclose the brain (i.e., Parietal, Frontal, Occipital, etc.)

Neurocranium

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This part of the cranium gives rise to bones that comprise the facial skeleton.

Viscerocranium

***This is pharyngeal arches

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The Neuocranium and Viscerocranium have ___________ and __________ components.

Cartilaginous

Membranous

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What makes up the cartilaginous parts of the Neurocranium?

Occipital bone
Body of sphenoid bone
Ethmoid bone
Petrous and Mastoid parts of the Temporal bone

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What makes up the membranous parts of the Neurocranium?

Calvaria – this makes up the Frontal and Parietal bones

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What makes up the cartilaginous parts of the Viscerocranium?

Neural Crest Cells give rise to bones and CT

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What makes up the membranous parts of the Viscerocranium?

Maxillary Prominence
Squamous part of Temporal bone
Maxilla
Zygomatic bone

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This is the term for the premature fusion of cranial sutures.

Craniosynostosis

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This is a type of Craniosynostosis where the Sagittal Suture fuses prematurely. Patient has a long, narrow, wedge-shaped cranium. It is the most common.

Scaphocephaly

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This is a type of Craniosynostosis where the entire coronal suture fuses prematurely. Patient has a high, tower-like cranium.

Brachycephaly

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This is a type of Craniosynostosis where one side of the coronal suture fuses prematurely. The cranium is twisted and asymmetric.

Plagiocephaly

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This is a type of Craniosynostosis where the frontal (metopic) suture fuses prematurely.

Trigonocephaly

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This external orofacial structure will form the forehead and dorsum/apex of the nose.

Frontal Nasal Prominence

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This external orofacial structure will form the alae of the nose.

Lateral Nasal Prominence

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This external orofacial structure will form the nasal septum, ethmoid bone, and cribriform plate.

Medial Nasal Prominence

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This external orofacial structure will form the upper cheek and upper lip.

Maxillary Prominence

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This external orofacial structure will form the chin, lower lip, and cheek.

Mandibular Prominence

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Brain development drives the shape/rate of growth of the head. During week 4, the 5 Facial Primordia will appear. These are…

2 Maxillary Prominences
2 Mandibular Prominences
1 Frontonasal Prominence

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The 5 Facial Primordia surround this in the center. It is the primitive oral cavity.

Stomodeum

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The Facial Primordia are separated from the primordial pharynx by the _________ _________. This ruptures around day 26.

Oropharyngeal Membrane

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These are the first parts of the face to form.

Lower jaw and lips

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The medial ends of these prominences fuse first. The Oropharyngeal Membrane disintegrates after this.

Mandibular Prominences

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If there is incomplete fusion of the Mandibular Prominences, what results?

Chin dimple

These prominences give rise to the upper lip, maxilla, and secondary palate. They grow medially and merge laterally with the Mandibular Prominences.

Maxillary Prominences

Primordial lips and cheeks (Maxillary Prominences) are invaded by mesenchyme from Pharyngeal Arch ______. This gives rise to the facial muscles.

This surrounds the ventrolateral part of the forebrain, and it gives rise to the forehead, rostral boundary of the stomodeum, and nose via nasal placodes.

Frontonasal Prominence

These are bilateral thickenings of surface ectoderm on the inferolateral portions of the Frontonasal Prominence.

Nasal Placodes

Nasal Placodes proliferate and cause horse-shoe shaped elevations, which are called...

Medial Nasal Prominence | Lateral Nasal Prominence

Nasal Placodes elevation results in formation of _______ _______ which are the primordial nares.

Nasal Pits

The Medial Nasal Prominences shift towards the midline with the medial growth of the _________ prominences. The fusion of the Medial Nasal Prominences results in formation of an intermaxillary segment called the __________.

Maxillary | Philtrum

The Lateral Nasal Prominences are initially separated from the Maxillary Prominences by the _________ _________. By the end of week 6, it has merged with the Maxillary Prominence.

Nasolacrimal Groove

In ear development, there are six ________ ________ that form around the first pharyngeal arch.

Auricular Hillocks

Development of the mandible pushes the ears where?

From the neck to the side of the head at eye level

While on your NICU rotation, you are called to the delivery room to evaluate a newborn who is in respiratory distress. Upon arriving to the delivery room, you notice that the baby is using accessory muscles in order to breathe. In addition, you notice that the baby demonstrates nasal flaring. From which structure did the flaring part of the baby's nose develop?

Lateral Nasal Prominence

Which signaling molecule is responsible for development of both mandibular processes and removing webbing from the hands/feet?

BMP

T/F. Facial development occurs slowing during the fetal period, but rather there are changes in proportion and relative positions of the facial components.

True

The nose is initially flat and the mandible is underdeveloped. They reach characteristic form by ______ weeks.

As the brain enlarges, the cranial cavity expands bilaterally. _______ move from lateral to forward-facing orientation.

Orbits

The small appearance of the face prenatally results from what?

Rudimentary upper and lower jaws Un-erupted deciduous teeth Small nasal cavities Small maxillary sinuses

Nasal Placodes depress and form Nasal Pits. Mesenchyme from the Medial and Lateral Nasal Prominences induce the Nasal Pits to become deeper. These are primordial...

Nasal Sacs

Primordial Nasal Sacs grow dorsally and ventrally to the forebrain. The ________ _________ separates the primordial Nasal Sacs, but this ruptures at the end of week 6.

Oronasal Membrane

This is the connection between the nasopharynx and the nasal cavity.

Choanae

These are nasal conchae, and can be inflamed with rhinitis (from allergies, etc.).

Superior, Middle, and Inferior Turbinates

This epithelium specializes into the olfactory nerve.

Olfactory Epithelium ***Fun fact -- Parkinson Disease patients will often have lost their sense of smell many years prior to onset of symptoms.

In Palatogenesis, there are two stages that occur between weeks _______. The critical period is the end of week ______ and the beginning of week ______.

6-12 6 9

The Primary Palate is formed by the fusion of the _______ ________ Prominences. This forms the Median Palatine Process.

Medial Nasal

The Median Palatine Process is located between the _________ prominences, and forms the premaxillary part of the maxilla.

Maxillary

The Secondary Palate develops from the Lateral Palatine Processes, or ________ ________.

Palatal Shelves

Palatal Shelves are mesenchymal projections extending from internal aspects of _________ prominences.

Maxillary

For the final palate, the bone extends from the maxillae and palatine bones into the lateral palatine processes to form the (SOFT/HARD) palate.

Hard

Posterior portions of the final palate do not ossify, this forms the...

Soft Palate | Uvula

This is what indicates the line of fusion for the palate.

Palatine Raphe

This is a remnant of the nasopalatine canal.

Incisive Fossa

The nasal septum is formed by the downward growth of internal parts of merged _______ _______ prominences. These parts fuse with lateral palatine processes anteriorly to posterior.

Medial Nasal

This is the most common craniofacial malformation. It is caused by defects in fusion and can be unilateral or bilateral.

Cleft lip and palate ***Unilateral cleft lip on the left is most common!

What can increase the risk for cleft lip or palate?

``` Genetics Environmental (smoking, drinking, folate deficiency, etc.) ```

This is associated with bony abnormalities of the pterygoid plates and midfacial growth abnormalities. Presents as upper airway obstruction, noisy breathing, or cyanosis that worsens during feeding and improves with crying.

Choanal Atresia ***Can be associated with Treacher-Collins, CHARGE, Kallman, or VACTERL syndromes

This occurs when the nasal septum doesn't grow straight down like it's supposed to. Easily fixable.

Deviated Septum

To form the anterior 2/3 of the tongue, these two things develop.

Median Lingual Swelling (Median Tongue Bud) | Lateral Lingual Swellings (Distal Tongue Buds)

The Median Lingual Swelling appears at the end of the ______ week.

4th

The two Lateral Lingual Swellings are induced by mesenchyme from which pharyngeal arch?

PA 1

The pharyngeal part in tongue development is made of what two things?

Copula | Hypopharyngeal Eminence

The Copula comes from the ventromedial parts of pharyngeal arch ______, and the Hypopharyngeal Eminence comes from the ventromedial parts of pharyngeal arches ______ and ______.

2 | 3 and 4

The Hypopharyngeal Eminence overgrows the Copula and the _______ ______ forms. This is where the fusion of oral and pharyngeal parts occurs.

Terminal Sulcus

Tongue musculature is derived from myoblasts of ________ ________. Innervated by CN XII (Hypoglossal).

Occipital Myotomes

What innervates the mucosa of the anterior 2/3 of the tongue?

Lingual branch of V3

What gives taste innervation to the anterior 2/3 of the tongue?

Chorda tympani (CN VII)

What innervates taste buds of the anterior 2/3 of the tongue?

CN IX (Glossopharyngeal)

What innervates the musculature of the anterior 2/3 of the tongue?

CN XII (Hypoglossal)

What innervates the mucosa and taste to the posterior 1/3 of the tongue?

CN IX (Glossopharyngeal)

What innervates the musculature of the posterior 1/3 of the tongue?

CN XII (Hypoglossal)

What innervates the sensation to the pharynx (posterior 1/3 tongue)?

CN X (Vagus)

What innervates the Palatoglossus M. (posterior 1/3 tongue)?

CN X (Vagus)

This is the term for a bifid tongue (snake tongue).

Glossoschissis

This is the term for a short frenulum. Can present with problems breastfeeding and speaking.

Ankyloglossia

This is the term for a big tongue. It is associated with Beckwith-Wiedemann and Down Syndromes mucopolysaccharidoses.

Macroglossia

Odontogenesis is induced by the communication between what?

NCC | Oral Epithelium

This is U-shaped bands of oral epithelium (surface ectoderm) that follow the curves of the primitive jaws.

Dental Laminae

These form out of the Dental Laminae and have 3 parts: Anterior Mandibular, Anterior Maxillary, and Posterior.

Tooth Buds

At this stage of tooth development, the tooth bud becomes cap-shaped when invested by mesenchyme.

Cap Stage

What does the tooth bud consist of?

Enamel organ Dental papilla Dental follicle/sac

Ectodermal cells from the dental lamina will differentiate into ________.

Enamel

What are the components of the Enamel organ?

Outer cell layer = Outer Enamel Epithelium Inner cell layer = Inner Enamel Epithelium Stellate Reticulum

The Dental Papilla is the internal part of the tooth, and it's made of...

Dentin | Pulp

The Dental follicle/sac is made of mesenchyme surrounding the dental papilla and enamel organ. It has ________, which anchors the teeth.

Cementum

Enamel organ becomes _______ shaped due to the differentiation of enamel.

Bell

These are from dental papilla cells next to the inner enamel epithelium. Predentin calcifies to become dentin.

Odontoblasts

These are made when inner enamel epithelium differentiates in response to dentin production. They produce enamel.

Ameloblasts

This is formed by the fusion of the inner and outer enamel epithelium. Contains root dentin (produced by odontoblasts).

Epithelial Root Sheath

This is the central dental papilla.

Pulp

This is on the outer cells of the dental sac, and they attach into cementum and anchor the tooth.

Periodontal Ligament

In tooth eruption, the root of the tooth and crown erupt through the oral epithelium. _________ teeth erupt first. Deciduous root is resorbed by __________, crown and upper root are shed.

Mandibular | Odontoclasts

Deciduous permanent teeth appear at approximately ______ weeks.