Face
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FACE AND PALATE DEVELOPMENT
Development of the Face — Weeks 4–10
The face develops from five main prominences surrounding the primitive mouth (stomodeum).
| Prominence | Major contribution |
|---|---|
| Frontonasal prominence | Forehead and bridge of nose |
| Medial nasal prominences | Philtrum of upper lip, premaxillary region and primary palate |
| Lateral nasal prominences | Alae of nose |
| Maxillary prominences | Lateral upper lip, cheeks and much of the maxilla |
| Mandibular prominences | Lower lip, chin and mandible |
Important fusion events
- The two medial nasal prominences merge to form the intermaxillary segment.
- The intermaxillary segment contributes to the philtrum, premaxillary region and primary palate.
- Maxillary prominences merge with the medial nasal prominences to form the upper lip.
- Mandibular prominences merge in the midline to form the lower jaw and lower lip.
Development of the Palate
The palate develops from the primary palate and secondary palate.
| Feature | Primary palate | Secondary palate |
|---|---|---|
| Origin | Intermaxillary segment | Palatal shelves from maxillary prominences |
| Position | Anterior to incisive foramen | Posterior to incisive foramen |
| Dental relevance | Associated with premaxillary region | Forms most of the hard and soft palate |
Secondary palate formation
- Palatal shelves develop from the maxillary prominences.
- Initially, the shelves lie vertically beside the tongue.
- They elevate into a horizontal position above the tongue.
- The shelves grow toward one another and fuse in the midline.
- Fusion with the primary palate and nasal septum completes separation of the oral and nasal cavities.
Cleft palate
Failure of palatal shelf elevation, growth or fusion can produce cleft palate.
MCQ tip: Primary palate = intermaxillary segment; secondary palate = palatal shelves.
Development of the Tongue
The tongue develops from multiple pharyngeal arches.
| Region | Embryological origin | Sensory supply |
|---|---|---|
| Anterior two-thirds | Mainly first arch | General sensation: lingual nerve (V3); taste: chorda tympani (VII) |
| Posterior one-third | Mainly third arch | Glossopharyngeal nerve (IX), for general sensation and taste |
| Epiglottic region | Fourth arch contribution | Internal laryngeal branch of superior laryngeal nerve (X) |
| Tongue muscles | Occipital somites | Mainly hypoglossal nerve (XII) |
Important exception: Palatoglossus is supplied by the vagus nerve through the pharyngeal plexus.