FOETAL SKULL/NEONATAL SKULL
DIMENSIONS STRUCTURE OF BONES POSTNATAL GROWTH OF SKULL SEX DIFFERENCES IN SKULL
CRANIOMETRY
DIMENSIONS
Skull is large in proportion to the other parts of skeleton.
Facial 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 facial 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 precocious growth of brain.
Base of the skull is short and narrow, though internal ear is almost of adult size, the
petrous temporal has not reached the adult length.
STRUCTURE OF BONES
The bones of cranial 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, superciliary arches and mastoid processes are not developed.
Paranasal Air Sinuses
These are rudimentary or absent.
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 later part of second year.
External acoustic meatus is short and straight. Its bony part is unossified and
represented by a fibrocartilaginous plate.
Tympanic membrane faces more downwards than laterally due to the absence of
mastoid process.
Stylomastoid foramen is exposed on the lateral surface of the skull because mastoid
portion is flat.
Styloid process lies immediately behind the tympanic ring and has not fused with the
remainder of the temporal bone.
8 Mandibular fossa is flat and placed more laterally, and the articular tubercle has not
developed.
9 The subarcuate fossa is very deep and prominent.
10 Facial canal is short.
Orbits
DIMENSIONS STRUCTURE OF BONES POSTNATAL GROWTH OF SKULL SEX DIFFERENCES IN SKULL
CRANIOMETRY
DIMENSIONS
Skull is large in proportion to the other parts of skeleton.
Facial 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 facial 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 precocious growth of brain.
Base of the skull is short and narrow, though internal ear is almost of adult size, the
petrous temporal has not reached the adult length.
STRUCTURE OF BONES
The bones of cranial 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, superciliary arches and mastoid processes are not developed.
Paranasal Air Sinuses
These are rudimentary or absent.
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 later part of second year.
External acoustic meatus is short and straight. Its bony part is unossified and
represented by a fibrocartilaginous plate.
Tympanic membrane faces more downwards than laterally due to the absence of
mastoid process.
Stylomastoid foramen is exposed on the lateral surface of the skull because mastoid
portion is flat.
Styloid process lies immediately behind the tympanic ring and has not fused with the
remainder of the temporal bone.
8 Mandibular fossa is flat and placed more laterally, and the articular tubercle has not
developed.
9 The subarcuate fossa is very deep and prominent.
10 Facial canal is short.
Orbits
