NEET MDS Lessons
Orthodontics
BONES OF THE SKULL
A) Bones of the cranial base:
A) Fontal (1)
B) Ethmoid (1)
C) Sphenoid (1)
D) Occipital (1)
B) Bones of the cranial vault:
1. Parietal (2)
2. Temporal (2)
C) Bones of the face:
Maxilla (2)
Mandible (1)
Nasal bone (2)
Lacrimal bone (2)
Zygomatic bone (2)
Palatine bone(2)
Infra nasal concha (2)
FUSION BETWEEN BONES
1. Syndesmosis: Membranous or ligamentus eg. Sutural point.
2. Synostosis: Bony union eg. symphysis menti.
3. Synchondrosis: Cartilaginous eg. sphenoccipital, spheno-ethmoidal.
GROWTH OF THE SKULL:
A) Cranium: 1. Base 2. Vault
B) Face: 1. Upper face 2.Lower face
CRANIAL BASE:
Cranial base grows at different cartilaginous suture. The cranial base may be divided into 3 areas.
1. The posterior part which extends from the occiput to the salatercica. The most important growth site spheno-occipital synchondrosis is situated here. It is active throughout the growing period and does not close until early adult life.
2. The middle portion extends from sella to foramen cecum and the sutural growth spheno-ethmoidal synchondrosis is situated here. The exact time of closing is not known but probably at the age of 7 years.
3. The anterior part is from foramen cecum and grows by surface deposition of bone in the frontal region and simultaneous development of frontal sinus.
CRANIAL VAULT:
The cranial vault grows as the brain grows. It is accelerated at infant. The growth is complete by 90% by the end of 5th year. At birth the sutures are wide sufficiently and become approximated during the 1st 2 years of life.
The development and extension of frontal sinus takes place particularly at the age of puberty and there is deposition of bone on the surfaces of cranial bone.