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Embryology · Head and neck: pharyngeal arches

Palate: primary and secondary palate !

  • Process

The roof of the mouth forms from a front triangle and two side shelves that rise and join over the tongue between weeks 6 and 10.

Updated 2026-11-01

See it in 3D: Maxillae · Palatine bones · Soft palate · Nasal septum · Vomer

What it is

The palate has two origins: the primary palate, a front triangle from the intermaxillary segment, and the secondary palate, made of two palatal shelves from the maxillary prominences. The shelves grow down beside the tongue, swing up to horizontal in week 7 and fuse with each other, with the primary palate and with the nasal septum. The incisive foramen marks the boundary between the two and is the landmark for classifying clefts.

Key facts

  • According to CDC, the lip forms between weeks 4 and 7 and the palate between weeks 6 and 9.
  • In female fetuses the shelves fuse about a week later, which is linked to isolated cleft palate being more common in girls.
  • A small mandible keeps the tongue from dropping and the shelves cannot rise (Pierre Robin).

Function

  • Primary palate: front of the maxilla (premaxilla) carrying the four incisors.
  • Secondary palate: hard palate behind the incisive foramen, soft palate and uvula.
  • Final separation of oral and nasal cavities; the choanae end up where the nose meets the pharynx.

Step by step

  1. Week 6: the primary palate is in place; the palatal shelves sprout from the maxillary prominences.
  2. The shelves grow down, vertically, on each side of the tongue.
  3. Week 7: the mandible grows, the tongue drops and the shelves rise to horizontal.
  4. The shelves meet in the midline; their edge epithelium disappears and the mesenchyme joins.
  5. In front they fuse with the primary palate; the incisive foramen marks the junction.
  6. The nasal septum grows down and joins the palate, separating the two nasal cavities.
  7. Fusion runs front to back and ends at the uvula around weeks 10–12.

Markers

  • IRF6
  • MSX1
  • TGF-β3
  • TBX22

Clinical notes

  • Clefts in front of the incisive foramen: cleft lip and cleft alveolar ridge.
  • Clefts behind it: secondary cleft palate and bifid uvula.
  • Submucous cleft palate: intact mucosa over muscle that has not joined; typical of 22q11.2 deletion.
  • Antiseizure drugs (valproate, phenytoin) and maternal smoking raise the risk of clefts.

Test yourself

Think of the answer, then tap the question to see it.

Where do the palatal shelves come from?

From the maxillary prominences (first arch).

Which landmark separates the primary from the secondary palate?

The incisive foramen.

Why can a small mandible cause cleft palate?

The tongue does not drop, stays between the palatal shelves and stops them rising and fusing.

In which week do the palatal shelves rise to horizontal?

In week 7 of development.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of embryology

Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given.

Sources: Cleft Lip/Cleft Palate | Birth Defects | CDC (Centers for Disease Control and Prevention, 2026); Embryology, Craniofacial Growth, And Development - StatPearls - NCBI Bookshelf (StatPearls Publishing (NCBI Bookshelf), 2023); Langman's Medical Embryology, 13th ed., ch. 17: Head and Neck (Wolters Kluwer, 2015).

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