Development of Palate

Development of Palate

Q. identify the structures labelled 1- 9.

Q. How is palate formed?

A. Palate develops from 1st pharyngeal arch and frontonasal process. It is formed from three processes:

1. Two palatine processes  of the maxillary processes.
2. Primitive palate which is formed from the  intermaxillary segment (premaxilla) of the  frontonasal process.

• The definitive palate is formed by the fusion of these three processes:
  • The primitive palate/primary palate fuses posteriorly with the two palatine processes
  • The two palatine processes fuse with each other in the midline to form the secondary palate.
• Later  the mesoderm in the palate undergoes intramembranous ossification to form the hard palate.
• Ossification does not occur in the posterior part which forms the soft palate.
• The muscles of soft palate are derived from the 4th pharyngeal arch.

Q. What the adult derivatives  of intermaxillary segment?

A. Following are the derivatives of intermaxillary segment:

1. Philtrum of upper lip.
2. Part of upper jaw with 4 incisors.
3. Primary/primitive palate.

 Q. What is  the embryological basis of cleft palate?

A.  The defective fusion of the three processes of developing palate result in cleft palate. These  defects vary in degrees and are as follows:

• Bilateral complete cleft palate:  Failure of fusion of both the palatine processes with each other and with the premaxilla/primitive palate. is is a ‘Y’ shaped cleft.
• Unilateral cleft palate:  Nonfusion of one side palatine process of maxilla with the premaxilla.
• Incomplete cleft palate:
  • Cleft limited to hard palate.
  • Cleft limited to soft palate.
  • Bifid uvula

Q. What are the common causes of cleft palate?

A.  The common causes could be:

– due to single gene mutation ,

– part of chromosomal syndrome  e.g. Down  syndrome, Edward syndrome.

–  Anticonvulsant drugs eg. Phenobarbitol or diphenylhydantoin taken during pregnacy.