Neonatal Skull or Foetal Skull

Neonatal Skull or Foetal Skull

DIMENSIONS:

• Skull is large in proportion to the other part of the skeleton.
• Foetal skeleton is small as compared to calvaria. In foetal skull, the facial skeleton is 1/7th of calvaria; in adults, it is half of calvaria. The foetal skeleton is small due to rudimentary mandible and maxillae, non-eruption of teeth, and small size of maxillary sinus and nasal cavity. The large size of calvaria is due to the precocious growth of brain.
• Base of skull is short and narrow, through internal ear is almost of adult size , the petrous temporal has not reached the adult lenght.

STRUCTURE OF BONES:

The bones of crainal vault are smooth and unilamellar; there is no diploe. The tables and diploes appear by fourth year of age.

BONY PROMINENCES:

1.Frontal and Parietal tubera are prominent.

2. Glabella, supercillary arches and mastoid processes are not developed.

PARANASAL AIR SINUSES:

These are absent or rudimentary.

TEMPORAL BONE:

• The internal ear, tympanic cavity, tympanic antrum, and ear ossicles are of adult size.
• The tympanic part is represented by an incomplete tympanic ring.
• Mastoid process is absent, it appears during the latter part of the second year.
• Facial canal is short.
• The subarcuate fossa is very deep and prominent.
• Mandible foosa is flat and placed more laterally, and the articular tubercle has not developed.

ORBITS:

These are large. The germs of developing teeth lies close to the orbital floor. Orbit comprises the base or an outer opening with upper, lower, medial and lateral walls. Its apex lies at the optic foramen/canal. It also has superior and inferior orbital fissures.