Concept about Fontanelle | CHAPTER 2 | Anatomy and Physiology

Concept about Fontanelle – The course is designed for the basic understanding of anatomical structures and physiological functions of human body, musculoskeletal system, digestive system, respiratory system; cardiovascular system; urinary system, endocrine system, reproductive system, nervous system, hematologic system, sensory organs, integumentary system, and immune system.
The aim of the course is to acquire knowledge and skills regarding anatomy and physiology.

Concept about Fontanelle

Fontanelle

A fontanelle (or fontanel) is an anatomical feature on an infant’s skull comprised by any of the soft membranous gaps between the incompletely formed cranial bones of a foetus or an infant. Fontanelles allow for rapid stretching and deformation of the cranium as the brain expands faster than the surrounding bone can grow.

• At birth, the skull features a small posterior fontanelle, an open area covered by a tough membrane, where the two parietal bones adjoin the occipital bone (at the lambda). This fontanelle usually closes during the first two to three months of an infant’s life. This is called intramembranous ossification. The mesenchymal connective tissue turns into bone tissue.
• The much larger, diamond-shaped anterior fontanelle where the two frontal and two parietal bones join generally remains open until the child is about two years of age, however, in cleidocranial dysostosis it is often late in closing or may never close. Examination of an infant includes palpating the anterior fontanelle.
• Two smaller fontanelles are located on each side of the head, more anteriorly the sphenoidal or anterolateral fontanelle (between the sphenoid, parietal, temporal, and frontal bones) and more posteriorly the mastoid or posterolateral fontanelle (between the temporal, occipital, and parietal bones).

Time of Fontanelle Closure

In humans, the sequence of fontanelle closure is as follows:

1. The posterior fontanelle generally closes 2-3 months after birth;
2. The sphenoidal fontanelle is the next to close around 6 months after birth;
3. The mastoid fontanelle closes next from 6 to 18 months after birth; and
4. The anterior fontanelle is generally the last to close between 18 month and 2 years of age (Ref:-http://en.wikipedia.org/wiki/Fontanelle#cite_note-TheFreeDictionary-1)

Functions of Fontanels

1. Enables the fetal skull to compress as it passes through the birth canal.
2. Permits rapid growth of the brain during infancy.
3. Assists in the determination of the fetal head position prior to birth.

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