2. NORMA BASALIS
2
It is subdivided into 3 parts
:
Anterior
Middle
Posterior
Imaginary
transverse line
passing through
the anterior
margin of the
foramen
magnum
6. 6
Hard palate
Sutures : palate is crossed by cruciform
suture; intermaxillary , interpalatine ,
palatomaxilary
Dome: arched in all directions, shows pits
for the palatine glands
8. Incisive fossa : deep fossa situated anteriorly
in the median plane
Two incisive canals: rt & lt pierce the walls of
the incisive fossa , one on each side
8
9. Greater palatine foramen
: on each side, situated
just behind the lateral
part of the
palatomaxillary suture
lesser palatine foramen :
two or three in number ,
lie behind the greater
palatine foramen ,
perforate pyramidal
process of palatine bone.
Posterior nasal spine :
posterior border of hard
palate .
Palatine crest : curved
ridge near the posterior9
11. Extends from the posterior border of the hard palate to the
transverse line passing through the anterior border of
foramen magnum
•Median area
•Lateral area 11
12. Median area :
Posterior border of
vomer, vomer separates
the two posterior nasal
apertures, inferior
border articulates with
the bony palate.
superior border splits
into two alae and
articulates with the
rostrum of the sphenoid
bone.
Broad bar of bone
formed by fusion of the
posterior part of the
body of the sphenoid
and basilar part of the12
15. Lateral area :
Two parts of sphenoid bone- pterygoid
process and greater wing
Pterygoid process- medial $ lateral
plate ; pterygoid fossa
Anterior border articulate with palatine
bone
Separated laterally from post surface
of the body of the maxilla by
pterygomaxillary fissure
15
17. •Medial pterygoid
plate-directed
backwards
•Medial and lateral
surfaces & free
posterior border
•Upper end of this
border divided to
enclose a triangular
depression called the
scaphoid fossa
•Medial to this fossa
there is a small
pterygoid tubercle
•Lower end of the 17
18. Sulcus tubae- groove between the
postromedial margin of the greater wing of
sphenoid bone and petrous temporal
bone. It lodges the cartilaginous part of
the auditory tube 18
20. •Inferior surface of the
petrous part of
temporal bone is
triangular in shape
• lies between the
greater wing of
sphenoid and
basioocciput
•Apex is perforated by
the upper end of the
carotid canal and is
separated from the
sphenoid by foramen
lacerum
•Carotid canal runs
forwards and medially
within the petrous
temporal bone
20
21. POSTERIOR PART OF NORMA
BASALIS• Median area –
1. Foramen magnum
2. External occipital crest
3. External occipital protuberance
4. Superior nuchal lines
21
22. 22
Lateral area :
a)Condylar part of occipital bone
b)Squamous part of occipital bone
c)Jugular foramen between occipital and
petrous temporal bones
d)Styloid process of temporal bone
e)Mastoid process of temporal bone
23. 23
• Occipital condyles : on
each side of the anterior
part of the FM, articulates
with the superior articular
facets of the atlas vertebra
to form atlanto-occipital
joint
• Hypoglossal canal/ant
condylar canal: directed
laterally and forwards
• Jugular foramen: forwards
$medially, placed at the
posterior end of the petro-
occipital suture
• Jugular fossa :ant wall of
the foramen is hollowed
out , lodges internal
jugular vein
24. ATTACHMENTS ON EXTERIOR
OF SKULL
1. Post border of the hard palate-
palatine aponurosis
2. Post nasal spine-musculus uvulae
3. Palatine crest- tensor veli palatine
muscle
4. Pharyngeal tubercle- superior
constrictor muscle
24
28. • FORAMEN MAGNUM
• Through wider posterior part
a. Lowest part of medulla oblongata
b. Three meninges
• Through the subarachnoid space
a. Spinal accessory nerves
b. Vertebral artery
c. Sympathetic plexus around the vertebral arteries
d. Posterior spinal arteries
e. Anterior spinal artery
• Through the narrow anterior part
a. Apical ligament of dens
b. Vertical band of cruciate ligament
c. Membrana tectoria
28
34. 4. Superior orbital fissure
Lateral part
lacrimal nerve, frontal nerve,
trochlear nerve, superior
ophthalmic vein, meningeal
branch of the lacrimal artery
Middle part
Upper and lower divisions of the
oculomotor nerve, nasociliary
nerve, abducent nerve
Medial part
inferior ophthalmic vein,
sympathetic plexus around ICA34
36. • Jugular foramen
1. Through anterior part
2. Through middle part
3. Through posterior part
36
37. • Mastoid canaliculus –in the lateral
wall of the jugular fossa auricular
branch of vagus
• Stylomastoid foramen- facial nerve ,
stylomastoid branch of the
posterior auricular artery
37
39. FEOTAL SKULL
39
Dimensions
Larger in proportion to other parts of skeleton
The facial skeleton is 1/8th of calvaria whereas it
is ½ of calvaria
Base of skull is short & narrow
Internal ear is of same size as in adult
Structure of bones :
Bones in cranial vault are smooth & unilamellar,
There is no diploe
Tables and diploe appear by fourth year of age
40. Bony Prominences
Frontal & Parietal tubera are prominent
Glabella, superciliary arches and mastoid
processes are not developed
paranasal air sinuses- rudimentary or
absent
orbits are large- germs of the developing
teeth lies close to the orbital floor
40
41. 41
Ossification of Bones
Two halves of frontal bone are separated by
metopic suture.
Mandible is also present in two halves
Occipital bone is in 4 parts ( (1)squamous, (2)
condylar, and (1) basilar)
Unossified membranous gap a total of 6
frontanelle at the angles of parietal bones are
present.
42. POST NATAL GROWTH OF SKULL
42
It proceeds at different rate and over different
periods
Growth of calvaria related to - growth of brain
Grwoth of facial skeleton related to -
development of dentition, muscle of
mastication & tongue
43. GROWTH OF VAULT
43
Rate – rapid during first yr.
slow upto 7th yr.
Growth in breadth : occurs at saggital suture
sutures bordering greater wings, Occipito
mastoid suture Petro- occipital suture at base
44. Growth in Height - occurs at
Frontozygomatic suture
Pterion
Squamous suture
Asterion
Growth in Anteroposterior Diameter - occurs at
coronal & lambdoid sutures
44
45. GROWTH OF BASE
45
It grows in antero-posterior diameter at 3
cartilaginous plates situated between –
Occipital & sphenoid bones
Pre & post sphenoid bones
Sphenoid & ethmoid bones
46. GROWTH OF FACE
Growth of orbits and ethmoid is
complete by 7th yr.
Growth occurs mostly during first
year, although continues till puberty
n even later
46
48. THICKENING OF BONES
48
Two tables and diploe appear by 4th yr.
Differentiation reaches maximum by about 35
yrs., when diploic vein produce characteristic
arking in radiographs
Mastoid process appear during 2nd yr, and
mastoid air cells during 6th yr.
49. OBLITERATION OF SUTURES OF VAULT
49
It begins on inner surface between 30-40 yrs. & on
outer surface between 40-50 yrs.
Occurs first in lower part of coronal suture
Posterior part of saggital suture
Lambdoid suture
50. AGE RELATED CHANGES
50
Skull becomes thinner & lighter
Reduction in size of maxilla and mandible
Decrease in vertical height of face
Angle of mandible becomes more obtuse
51. CRANIOMETRY
51
1. Cephalic Index
it expresses shape of head,& is the proportion of
breadth to length of skull
cephalic index = breadth x 100
length
Length/ longest diameter – measured from
glabella to occipital point
Breadth / widest diameter – measured a little
below parietal tubera
52. Human races may be-
a. Dolichocephalic or long headed ( when C.I
is 75 or less)
b. Mesaticephalic ( when C.I is between 75
and 80)
c. Brachycephalic or Short headed (when C.I
is above 80)
52
53. FACIAL ANGLE
Is the angle between 2 lines drwan
from the nasion to th basion or
anterior margin of foramen magnum
and the prosthion or central point
on upper incisor alveolus
It is a rough index of degree of
devlopment of brain because it is
angle between facial skeleton and
calvaria, which are inversely
propotional to each other.
Angle – smallest-
evolved races of man 53
54. ABNORMAL CRANIA
Oxycephaly or Acrocephaly – tower
like skull or steeple skull is a
abnormally tall skull.
- Occurs due to premature closure of
suture between presphenoid and
postsphenoid and coronal suture
Scaphocephaly or boat shaped
skull is due to premature synostosis
in saggital suture
54
