This site is 100% ad supported. Please add an exception to adblock for this site.

Formation of the Face


undefined, object
copy deck
The face is derived from what 5 primordia:
FP = frontal process
MNP = medial nasal process
LNP = lateral nasal process
MaxP = maxillary process
ManP = mandibular process
What is FUSION?
Joining of FREE processes; involves epithelial disintegraion.
What is MERGING?
Joining of incompletely separated processes b removing the intervening groove between them.
Which of the face primordia has already joined prior to face formation?
Mandibular processes
What are the lateral/medial nasal processes?
Elevations that surround the olfactory placodes; caused by growth of the Frontal Process.
What are the 5 steps in face formation?
1. MaxP fuses with LNP
2. MAXP merges with FP
3. 2 MNPs merge
4. MAXP fuses with MNP
5. Maxp merges with ManP
Where do the MNP and LNP arise from?
Olfactory placodes on FP
Where do MaxP and ManP arise from (what arch)?
Arch 1
What is dacryostenosis?
Failure of the nasolacrimal duct to canalize
What happens to the olfactory placode when the MNP/LNP form?
It becomes the NASAL PIT floor
What develops as a result of MaxP fusing with LNP and merging with FP? (steps 1/2)
The nasolacrimal duct and sac.
What is dacryostenosis again?
Failure of canalization of the nasolacrimal duct.
What happens after MaxP fuses w/ LNP and merges w/ FP? (Step 3) What is the result?
The 2 MNP's merge to form the Intermaxillary segment
What 3 things make up the intermaxillary segment?
1. Middle upper lip (philtrum)
2. Incisor bridge of upper jaw
3. Primary Palate
What happens after forming the intermaxillary segment? (Step 4)
MNP fuses w/ Max P to create the Nasal Fin
What is the purpose of the nasal fin?
It separates the nasal pit from the oral cavity.
What is the last step of face formation?
MaxP merges with ManP to form the CHEEKS.
How does the nose develop?
1. LNP makes the Nose Ala
2. MNP + FP make the bridge, top, and between external nares
Define Choanae:
the openings between the nasal cavity and pharynx
What direction does the nasal cavity enlarge in?
How do the primitive choanae form?
1. Oronasal membrane stretches
2. Membrane ruptures
3. Forms Primitive Choanae
What is Choanal atresia?
Absence of one or both primitive choanae due to obstruction (usually bone)
What does bone obstruction to choanae development result in?
Failure of oronasal membrane to rupture by 38 days.
What type of situation results in bilateral choanal atresia?
Emergency! Respiratory distress immediately.
What is the Ethmoid Bone responsible for?
Orbital separation and nasal cavity growth.
What 2 conditions can result from abnormal ethmoid devo?
1. Hypotelorism
2. Hypertelorism
What causes hypotelorism? what is it?
Small ethmoid - eyes too close
What causes hypertelorism? What is it?
Big ethmoid - eyes too wide
By what week is human facial form achieved?
Weke 8
What does elongation and hypertrophy of Arch 1 accomplish?
-Ears moving superdorsally
-Eyes moving toward midline
What is the ratio of cranium:face size in
Newbie = 8:1

Acult = 3:1
What do the 1' and 2' palates form together?
The hard palate
What causes the formation of the primary palate?
The merging of the MNP's
What forms the secondary palate?
-Palatine processes - of the maxillary and palatine bones.
What drives the apposition and fusion of the palatine plates?
Shelf force - directed force that elevates the palatal processes to a horizontal pos.
What is essential for proper palate fusion?
Inferior movement of the tongue as the mandibular arch grows ant-posteriorly.
What cell process allows fusion of the palatine processes?
What is the last part of the palate to develop?
Soft palate - from mesenchymal proliferation of the caudal 2' palate; LASTLY = uvula
What causes a Lateral Cleft Lip?
Failure of 1' and 2' palates to fuse
What causes a median cleft lip?
Failure of the MNPs to merge (to form the 1' palate)
What causes an Oblique Facial Cleft?
Failure of the MaxP and ManP to merge
What causes a Cleft Palate?
Failure of the 2' palate to fuse
What is the most common type of cleft LIP?
Lateral (uni or bi)
What are the common characteristics of lateral cleft lip?
-Left side
What are the common qualities of cleft PALATE?
-Seen w/ Cleft LIP
-Females 2x as often
-Specific factors lead to it
What 3 morphogenic factors lead to cleft palate?
1. Abnormal tongue devo (fails to move down during 2' fusion)
2. Cysts - remnants of fusion
3. Impediment of shelf force
What can impede the shelf force?
Glucocorticoids at pharmocologic levels
What is cleft palate by itself NOT influenced by?
What is Cleft lip by itself not influenced by?
Maternal Age
What are Cleft lip AND palate together not influenced by?
What are 3 types of First Arch Syndromes?
1. Mandibulofacial Dysostasis
2. Maxillary hypoplasia
3. Mandibular hypoplasia
What is another name for Mandib dysostasis?
What symptoms?
Treacher Collins Syndrome
-Slanting eye crease
-Clefts of arch 1 structures
-Deaf, lower lid coloboma
What is another name for maxillary hypoplasia?
-Hypoplastic midface
-Coronal suture synostosis
What is another name for mandibular hypoplasia?
Pierre Robin Sequence
-Small jaw
-Difficulty breathing
-Cleft palate
What is CHARGE association?
A set of anomalies that are often seen together.
What does CHARGE stand for?
-Coloboma of the eye
-Heart Defects
-Atresia (of choana)
-Genital Hypoplasia
-Ear anomalies
What determines if a patient has charge?
4/6 anomalies must be present
What is holoprosencephaly?
All midline defects of forebrain and face.
What are 3 associated "faces" assoc w/ holoprosencephaly?
1. Cyclopia (maybe proboscis)
2. Ethmocephaly (Hypotelorism+)
3. Cebocephaly (Hypotelorism + single nostril + proboscis)
What is the mildest form of holoprosencephaly?
Single maxillary incisor
What 4 factors are associated with holoprosencephaly?
1. Toluene inhalation
2. Maternal diabetes
3. Fetal alcohol syndrome
4. Trisomy conditions
What is Apert's syndrome?
Towering skull
-Flat midface area
-Cleft palate
-Variable intelligence
Symptoms of Accutane induced facial dysplasia:
-First arch defects
-Ear anomalies
-Skin problems
-Cleft lip and palate
What is Lateral Facial Dysplasia?
Syndrome of the 1st/2nd arches; Affects one side only.
What are the symptoms of lateral facial dysplasia?
-Small mouth
-One side of face small
-Microtia (small ear)
-Hemivertebrae/hypoplastic vert.
What is a Proboscis?
A blind end tube-like structure.

Deck Info