Embryology of the skull

Question 1

How are the bones in the Calvaria/Cranial Cap/ Cranial Top joined/formed?

Answer 1

They are joined/formed through a process called intramembranous ossification

Intramenbranous means membrane are formed first

Question 2

How are the bones in the Cranial Base joined/formed?

Answer 2

They are joined/formed through a process called endochondral ossification

Endochondral means cartilage is formed first.

Question 3

What are Fontalles?

Answer 3

Fontalles is where the sutures meet and are made of strong fibrous tissue/membrane

Question 4

What are the two functions of fontanelles

Answer 4

• Allows skull to compress during birth

- Helps the skull expand during first year of life as the brain expands

Question 5

How many Fontanelles are there?

Answer 5

6 fontanelles

• Anterior fontanelle ( Bergma) (Top of Head)
• 2 Anterior Lateral fontanelle (Pterion) (Top behind ear)
• 2 Posterior Lateral fontanelle (Asterion) ( Side and back of head)
• Posterior fontanelle (Lambda) ( back of the head)