Face, Palate, Nasal, Tongue Development Softchalk

Question 1

What forms the major portion of the palate?

Answer 1

Lateral palatine processes

Question 2

Explain the formation of the nasal placodes, nasal pits, and nasolacrimal groove

Answer 2

• Nasal placodes (week 5): formed by two thickenings of surface ectoderm on frontonasal prominence
• Nasal pits (week 6): oval-shaped invaginated ectoderm at center of each nasal placode. These divide the frontonasal prominence into lateral and medial nasal processes
• Nasolacrimal groove: groove between maxillary prominence and the lateral nasal process. Will become the nasolacrimal duct.

Question 3

Explain the development of the intermaxillary segment

Answer 3

During week 7, the two medial nasal processes fuse to form the intermaxillary segments. (If they fail to fuse, a median cleft lip arises = rare.)

Question 4

Describe the embryological cause of the unilateral and bilateral cleft lip.

Answer 4

Failure of the intermaxillary segment and maxillary prominence to fuse on one side (unilateral) or on both sides (bilateral)

Question 5

Describe the formation of the primary palate

Answer 5

[The palate develops in two stages: primary palate followed by secondary palate.]
The primary palate (and incisor teeth) are formed by the merging of the medial nasal prominences = the intermaxillary segment.

Question 6

Identify the embryological cause for each type of cleft palate

Answer 6

• Complete or partial anterior cleft palate: lateral palatine processes fail to fuse with the primary palate. Extends through the lip to the incisive foramen.
• Posterior cleft palate: lateral palatine processes fail to fuse with each other and with the nasal septum
• Complete cleft palate: lateral palatine processes fail to fuse with each other, nasal septum, and the primary palate. Can be unilateral or bilateral.

Question 7

Explain the clinical presentation and embryological cause of the choanal atresia.

Answer 7

Clinical presentation of choanal atresia: Newborn infant crying vigorously at birth, but as soon as he stops crying he becomes breathless and cyanotic.
Cause: Persistence of an intact oronasal membrane and lack of communication between nasal cavities and nasopharynx. Can be unilateral or bilateral.

Question 8

What is CHARGE syndrome?

Answer 8

An autosomal dominant disorder, including:

• Coloboma of the eye
• Heart defects
• Atresia of the choanae
• Retardation of growth and/or development
• Genital and/or urinary abnormalities
• Ear abnormalities and deafness