Head and neck

The palate, and how a cleft happens

5 steps · 3 anomalies · Weeks 5 to 6 to Weeks 9 to 12

Read this first

The clearest example of why embryology is worth learning as a story. A cleft is not a random defect; it is a fusion that did not happen, at a date you can name, between two processes you can name. Learn the incisive foramen as the boundary and you can classify any cleft on sight.

Weeks 5 to 6

Step 1 of 5

What happens: The two medial nasal processes fuse in the midline to form the intermaxillary segment.
What it forms: The primary palate, together with the philtrum of the upper lip and the premaxilla.
What remains in the adult: The small triangle of hard palate in front of the incisive foramen, carrying the four incisor teeth.

If this step fails

Median cleft lip
The two medial nasal processes fail to fuse with each other, so the gap is in the midline. It is rare, and unlike the common cleft lip.

Every anomaly, and the step it blames

This is the table the examiner is working from. Read the clue column first and see whether you can name the step before you look.

Cleft lip
You are told: A newborn with a gap in the upper lip lateral to the midline, on one or both sides.
Failed step: Each maxillary process grows medially and fuses with the medial nasal process on its own side. (week 6)
The maxillary process fails to fuse with the medial nasal process on that side. It lies in front of the incisive foramen and may be unilateral or bilateral.
Cleft palate
You are told: A newborn with feeding difficulty and nasal regurgitation of milk.
Failed step: The shelves fuse with each other in the midline, with the primary palate in front and with the nasal septum above. (week 10)
The palatine shelves fail to fuse with each other, behind the incisive foramen. It can involve the soft palate alone or extend forwards through the hard palate.
Median cleft lip
You are told: A defect exactly in the middle of the upper lip.
Failed step: The two medial nasal processes fuse in the midline to form the intermaxillary segment. (week 5)
The two medial nasal processes fail to fuse with each other, so the gap is in the midline. It is rare, and unlike the common cleft lip.

Viva voce

1 of 5 · 0 answered

Say your answer out loud before you open it. That is the exam skill.

What is the landmark that separates anterior from posterior clefts?

If you remember nothing else

The incisive foramen divides anterior clefts from posterior ones
The primary palate comes from the intermaxillary segment
The secondary palate comes from two shelves that must first rotate

Do not confuse it with

Cleft lip versus cleft palate
Cleft lip lies in front of the incisive foramen and is a failure of the maxillary and medial nasal processes to fuse; cleft palate lies behind it and is a failure of the palatine shelves to fuse. They have different dates and different mechanisms, and either can occur alone.

Examiner trap

Calling every facial cleft a failure of the same fusion. Lip and palate fail at different steps, weeks apart, and either can happen without the other.

Memory hook

In front of the incisive foramen it is the lip; behind it, the palate.

Senior’s 30-second takeaway

The palate, and how a cleft happens — the whole bench in four lines. Read this on the way in.

If you see this: A cleft described as in front of or behind the incisive foramen · A newborn with nasal regurgitation · A question naming the medial nasal or maxillary process
If asked to identify it: A cleft is a fusion that failed, and the incisive foramen tells you which fusion it was.
If asked one more: The shelves must rotate from vertical to horizontal before they can fuse at all.
If asked why it matters: Cleft palate causes feeding difficulty and nasal regurgitation because mouth and nose are still one cavity.

Then stop. Let the examiner ask the next question.

🧬 Read this first

Every anomaly, and the step it blames

🎙️ Viva voce

Senior’s 30-second takeaway

Read this first

Viva voce