Lecture notes of frontanelle of human skull of children

Frontanelle :  

Definition :

A fontanelle is an anatomical feature of the infant human skull. They are soft membranous gaps between the cranial bones.

Clinical importance of frontanelle: 

1. The fontanelle allows the skull to deform during birth to ease its passage through the birth canal 

2. and for expansion of the brain after birth.

3. A sunken fontanelle indicates dehydration 

4. whereas a very tense or bulging anterior fontanelle indicates raised intracranial pressure

 

Number of frontanalle in human skull of children : 4 

1. anterior frontanelle 
2. Posterior frontanelle 
3. sphenoidal frontanelle 
4. mastoid frontanelle

Anterior frontanelle: 

Anterior superior angle of parietal bone forms bregma in children it is called anterior frontanelle The anterior fontanelle bregmatic fontanelle, frontal fontanelle is the largest fontanelle, and is placed at the junction of the sagittal suture, coronal suture, and frontal suture;
It is lozenge shaped, and measures about 4 cm in its antero posterior and 2.5 cm in its transverse diameter.
The anterior fontanelle typically closes between the ages of 12 and 18 months.

Posterior frontanelle :
Posterior superior angle forms Lambda in children it is called posterior fontanelle
The posterior fontanelle lambdoid fontanelle, occipital fontanelle is a gap between bones in the human skull known as fontanelle, triangular in form and situated at the junction of the sagittal suture and  lambdoidal suture.
It generally closes in 6 to 8 weeks from birth.
A delay in closure is associated with congenital hypothyroidism.
Premature complete ossification of the sutures is called craniosynostosis.

Sphenoidal frontanelle:
Anterior inferior angle of parietal bone forms pterion in children it is called sphenoidal frontanelle
This angle is internally marked by groove for anterior division of middle meningeal artery
What is pterion
Ans union between 4 bones
Frontal bone
Anterior inferior angle of parietal bone
Greater wing of sphenoid
Squamous part of temporal bone
What is the importance of pterion
Internal surface of pterion is lodged by anterior division of middle meningeal artery 

Mastoid frontanelle :
Posterior inferior angle of parietal bone forms asterion in children it is called mastoid frontanelle
Internally a groove is present which lodges sigmoid sinus
Summary of Closure of frontanelle
In humans, the sequence of fontanelle closure is as follows
The posterior fontanelle generally closes 2 to 3 months after birth;
The sphenoidal fontanelle is the next to close around 6 months after birth
The mastoid fontanelle closes next from 6 to 18 months after birth; and
The anterior fontanelle is generally the last to close between 12 to 18 months.