Question

1. How does the nose develop (in detail)?

2. How does the palate develop (in detail)?

3. List and explain possible abnormalities of palate development (figure not necessary).

4. List the commissures found in the prosencephalon.

5. Link segmentation with the rearrangement of the the back muscles.

Answer 1

Q1. Development of nose

Nose consists of external nose and nasal cavity

Development of external nose :-

External nose develops from five facial process process, frontonasal process, two medial nasal processes, and two lateral nasal processes

The fronto nasal process forms the bridge of the nose. Two fused medial nasal processes form dorsum and tip of the nose. Two lateral nasal processes form side and alae of nose.

Development of nasal cavities:-

The nasal cavities develop from ectodermal nasal pits. The nasal pits deepen dorsally during the 6th week of intrauterine life to form Nasal sacs. Each nasal sacs grows dorsoventrally to developing forebrain to form primitive nasal cavity. dorsal end of primitive nasal cavity is separated from oral cavity by oronasal membrane.At the end of sixth week this membrane rupture to form primitive choanaea and as a result the nasal cavity communicate with the primitive oral cavity. the primitive choanae lie at the junction of primitive Nasal and oral cavities, immediately behind primitive palate. Later with further growth of primitive Nasal cavity and formation of secondary palatethe definitive choanae lie at the junction of the nasl cavity and nasopharynx.

External opening of nasal pits persist as external nares.

Superior, middle, and inferior nasal conchae develop as curved elevations from the lateral wall of nasal cavity.

Ectoderm lining the roof of the nasal cavity become specialised to form olfactory epithelium which provides origin of olfactory nerves.