42 Questions
What is the cause of anterior cleft defects?
Failure of mesenchyme in the maxillary prominences and the median palatine process
What is the gender distribution among affected neonates with a cleft lip?
80% male and 20% female
What causes a persistent labia groove resulting in a unilateral cleft lip?
Failure of the mesenchymal masses to merge and proliferate
What happens in the case of a complete bilateral cleft lip?
The median palatal process hangs free and projects anteriorly
What causes a median cleft lip?
Failure of mesenchyme in the maxillary prominences and the median palatine process
What is the gender distribution among affected individuals with cleft lip and palate?
More common in boys than in girls
What gene is involved in the formation of isolated clefts?
Interferon regulatory factor 6 gene (IRF6)
What is the recurrence risk in subsequent siblings when neither parent is affected by cleft lip and alveolar process of the maxilla?
~4%
What causes clefts of the posterior palate (clefts posterior to the incisive fossa)?
Failure of mesenchymal masses in the lateral palatine processes to meet and fuse with each other and the nasal septum
What causes clefts of the secondary parts of the palate?
Failure of mesenchymal masses in the lateral palatine processes to meet and fuse with mesenchyme in the primary palate
Which of the following is a common craniofacial birth defect?
Cleft lip and cleft palate
Where are small auricular sinuses and cysts usually located?
In front of the external ear
What causes congenital atresia of the nasolacrimal duct?
Failure to canalize part of the nasolacrimal duct
What are auricular sinuses and cysts classified as?
Minor defects with no serious medical consequences
Which part of the face may be affected by clefts?
Lips and palate
What are remnants of the first pharyngeal groove associated with?
Congenital auricular sinuses and cysts
Where are auricular sinuses and cysts usually located?
In front of the external ear
What is the approximate occurrence rate of nasolacrimal duct obstruction in neonates?
~6%
"Little anomalies that do not cause clinical importance" refers to which condition?
Congenital auricular sinuses and cysts
Which of the following facial defects results from the incomplete merging of the medial nasal prominences?
Bifid nose
What is a characteristic feature of a mild form of bifid nose?
Groove in the tip of the nose
Severe clefts are usually associated with what in the head?
Gross defects
What type of facial clefts are often bilateral and extend from the upper lip to the medial margin of the orbita?
Oblique facial clefts
Bilateral clefts can result in what characteristic feature?
Macrostomia (very large mouth)
What is the term for teeth that have erupted by the time of birth?
Natal teeth
What condition is often caused by a deficiency in vitamin D (rickets)?
Deficient enamel on teeth
'Oblique facial clefts' are associated with which of the following?
Failure of mesenchymal masses to merge with nasal prominences
What imaging technique is used to readily recognize facial defects such as a cleft lip during the second trimester?
Ultrasound imaging technique
Abnormalities in the number, shape, and size of teeth can be influenced by which factors?
Genetic and environmental influences
What is the term for a condition where teeth may be deficient in enamel?
Enamel hypoplasia
Abnormally formed and inadequately enameled mandibular incisors can be indicative of what condition?
Enamel hypoplasia
Which of the following facial defects is associated with underdevelopment (hypoplasia) of the mandible in severe cases?
Congenital microstomia
What is the result of excessive merging of the mesenchymal masses in the maxillary and mandibular prominences of the first pharyngeal arch?
Microstomia
What results from the occurrence of a single nostril due to the formation of only one nasal placode?
Bifid nose
What type of facial clefts result from the failure of mesenchymal masses in the maxillary prominences to merge with the lateral and medial nasal prominences?
Oblique facial clefts
Which condition involves teeth that have erupted by the time of birth, usually involving the mandibular incisors and may be abnormally formed with little enamel?
Natal teeth
What is the result of bilateral oblique facial clefts extending from the mouth toward the ear?
Macrostomia
What causes tooth abnormalities such as abnormal number, shape, and size or discoloration by foreign substances?
Vitamin D deficiency
What can be identified sonographically at the beginning of the second trimester using imaging techniques?
Facial defects such as a cleft lip
What is a common occurrence associated with severe clefts in terms of head defects?
Gross defects of the head
What may result from underdevelopment (hypoplasia) of the mandible in severe cases of congenital microstomia?
Macrostomia
Where are small auricular sinuses and cysts usually located?
In the cheeks extending almost to ears
Study Notes
Cleft Defects
- Anterior cleft defects are caused by failure of the medial nasal prominences to merge properly.
Gender Distribution
- In affected neonates, the gender distribution is 2:1 male to female for cleft lip.
Unilateral Cleft Lip
- A persistent labia groove results in a unilateral cleft lip.
Bilateral Cleft Lip
- In complete bilateral cleft lip, the premaxilla is separate from the maxilla.
Median Cleft Lip
- Median cleft lip is caused by failure of the frontonasal prominence to merge properly.
Gender Distribution for Cleft Lip and Palate
- The gender distribution for cleft lip and palate is 2:1 male to female.
Genetics of Clefts
- The IRF6 gene is involved in the formation of isolated clefts.
Recurrence Risk
- The recurrence risk in subsequent siblings when neither parent is affected is 4-6%.
Clefts of the Posterior Palate
- Clefts of the posterior palate are caused by failure of the palatine shelves to fuse.
Clefts of the Secondary Palate
- Clefts of the secondary palate are caused by failure of the lateral palatine shelves to fuse.
Common Craniofacial Birth Defect
- Cleft lip and palate is a common craniofacial birth defect.
Auricular Sinuses and Cysts
- Auricular sinuses and cysts are usually located in front of the ear and are classified as congenital anomalies.
Congenital Atresia of the Nasolacrimal Duct
- Congenital atresia of the nasolacrimal duct is caused by failure of the nasolacrimal groove to develop.
Minor Anomalies
- "Little anomalies that do not cause clinical importance" refers to minor anomalies.
Facial Clefts
- Facial clefts can affect the upper lip, alveolar process, hard palate, and soft palate.
Nasolacrimal Duct Obstruction
- The approximate occurrence rate of nasolacrimal duct obstruction in neonates is 20%.
Miscellaneous
- Natal teeth are teeth that have erupted by the time of birth.
- Rickets can cause abnormalities in tooth development.
- Oblique facial clefts are associated with hypoplasia of the maxillary process.
- Facial defects such as cleft lip can be readily recognized by ultrasonography during the second trimester.
- Abnormalities in tooth development can be influenced by genetics, environment, and nutrition.
- Hypoplasia of the mandible can result in microstomia.
- Fusion of the maxillary and mandibular prominences can result in a single nostril.
Test your knowledge on the developmental anomalies of the face and identifying types of cleft lip and palate with this quiz. Learn about atresia of the nasolacrimal duct and other congenital anomalies.
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