1. Skull is formed of:
- Cranium
- Mandible
Cranium is formed of:
- Brain box (calvaria)
- Facial skeleton
Facial skeleton is formed of:
- An upper fixed part
- A lower mobile part (the mandbile)
General features
SKULL
Normae of the skull
1. Norma verticalis
2. Norma frontalis
3. Norma lateralis
4. Norma occipitalis
5. Norma basalis:
- externa
- interna

2. Norma verticalis (Superior view)
Bones to be identified:
• Frontal bone
• Parietal bones
• Occiptial bone
Sutures:
• Sagittal suture, between the 2 parietal bones
• Coronal suture, between the frontal & the
two parietal bones
• Lambdoid suture, between the occipital and
the two parietal bones
Features:
• Bregma, point of meeting of
sagittal & coronal sutures
• Lambda, point of meeting of
sagittal & lambdoid sutures
• Frontal tuber, most prominent
area on the frontal bone
• Parietal tuber, most prominent
area on the parietal bone
• Parietal foramen, transmits the
parietal emissary vein
Frontal bone
Frontal tuber
Bregma
Coronal suture
Sagittal suture
Parietal tuber
Parietal foramen
Lambda
Lambdoid suture
Occipital bone
Parietalbone

3. Anterior fontanelle:
•A rhomboidal membrane that closes the gap present at the site of the bregma in the fetal skull.
•Obliterated in the middle of the second year after birth.
Frontal bone
Parietal bone
Lambdoid suture
Occipital bone
Posterior fontanelle
Sagittal suture
Coronal suture
Anterior fontanelle
Posterior fontanelle:
•A triangular membrane that closes the gap present at the site of the lambda in the fetal skull.
•Obliterated in the first 3 months after birth.

4. Norma frontalis (Anterior view)
Bones to be identified:
•Frontal bone
•Nasal bones
•Zygomatic bones
•Maxillary bones
•Mandible
Sutures:
•Fronto-nasal
•Fronto-zygomatic
•Inte-rnasal
•Inter-maxillary
•Maxillo-zygomatic
Frontal bone
Frontal tuber
Glabella
Nasal bone
Zygomatic bone
Maxilla
Mental foramen
Body of
the mandible
Ramus of
the mandible
Infra-orbital
foramen
Zygomatico-facial
foramen
Supra-orbital
foramen

5. • Three large openings:
-2 orbital openings
-anterior nasal aperture; bound by
the nasal bones and maxillae
• Anterior nasal spine; a median
projection on the lower margin of the
anterior nasal aperture
• Nasion, point of meeting of fronto-
nasal & internasal sutures
• Glabella, elevation above the nasion
• Supercilliary arches, transverse
ridges extending laterally from the
glabella
• Frontal tuber, the most prominent
area of the frontal bone
• Foramina:
1. Supra-orbital foramen (notch)
2. Infra-orbital foramen
3. Zygomatico-facial foramen
4. Mental foramen
Frontal bone
Frontal tuber
Glabella
Mental foramen
Supra-orbital
foramen
Features of norma frontalis:
Nasion
Zygomatico-facial
foramen
Infra-orbital
foramen
Anterior nasal
spine

6. Norma lateralis (Lateral view)
Bones to be identified:
Above the level of zygomatic arch:
• Frontal bone
• Parietal bone
• Occipital bone
• Greater wing of sphenoid bone
• Squamous part of temporal bone
Zygomatic process of
temporal bone (zygoma)
Temporal process
of zygomatic bone
Zygomatic
arch
Frontal
bone
Parietalbone
O
ccipital
bone
Greater wing
of sphenoid bone
Squamous part
of temporal bone
Zygomatic arch, Formed by the temporal process of zygomatic
bone and zygomatic process of temporal bone (zygoma)

7. Bones to be identified:
Below the level of zygomatic arch:
• Mastoid part of temporal bone, projects
downwards forming the mastoid process
• Tympanic part of temporal bone
• Pterygoid process of sphenoid bone
• Maxilla
Squamous part
of temporal bone
Mastoid part
of temporal bone
Tympanic part
of temporal bone
Greater wing
of sphenoid bone
Pterygoid process
of sphenoid bone
Maxilla
Tympanic part
of temporal bone
Mastoid process
Ramus of
the mandible
Squamous part
of temporal bone

8. Features of norma lateralis
Styloid process
• Pterion, region of meeting of frontal, parietal, squamous part of temporal and greater wing
of sphenoid bones. It lies 35mm behind and 12mm above the fronto-zygomatic suture.
• Asterion, region of meeting of lambdoid, parietomastoid and occipitomastoid sutures.
Pterion
Asterion

9. • Temporal line, begins behind the lateral orbital margin, follows a curved course on the
frontal, parietal and temporal bones, forms a ridge at the base of mastoid bone (supra-
mastoid crest) and continues with the posterior root of zygoma.
• External acoustic meatus, below the posterior root of the zygoma
• Pterygoid process, formed of a lateral and medial pterygoid plates separated by the
pterygoid fossa
Superior & inferior
Temporal lines
Supramastoid
crest
Mastoid part
of temporal bone
Mastoid process
External
acoustic meatus
Lateral & medial
pterygoid platesPterygoid
fossa

10. • Temporal fossa, the area bound by the temporal line
• Infratemporal fossa, the space below the greater wing of sphenoid and deep to the ramus
of the mandible.
• Pterygo-maxillary fissure, between the maxilla (anteriorly) and the pterygoid process
(posteriorly), it connects the infratemporal fossa with the pterygopalatine fossa.
• Inferior orbital fissure, connects the infratemporal fossa with the orbital cavity.
Temporal lines
Temporal fossa
Greater wing
of sphenoid bone
Pterygoid process
of sphenoid bone
Maxilla
Squamous part
of temporal bone
Pterygo-maxillary
fissure
• Styloid process, a long slender process directed downwards and forwards
Styloid process

11. Norma occipitalis (Posterior view)
Bones to be identified:
• Parietal bones
• Squamous part of occiptial bone
• Mastoid part of temporal bone
Features to be identified:
• External occipital protuberance
• External occipital crest
• Superior nuchal lines
• Highest nuchal lines
• Lambda
• Asterion
• Mastoid foramen
• Parietal foramen
Sutures to be identified:
• Sagittal suture
• Lambdoid suture
• Parietomastoid suture
• Occipitomastoid suture
Parietal bone
Squamous part
of occipital bone
Mastoid
bone
External occipital
protuberance
Parietal
foramen
Sagittal
sutureLambda
Asterion
Sup nuchal
line
Occipitomastoid
suture
Lambdoid suture
Parietomastoid
suture
External occipital
crest
Inferior nuchal
line

12. Foramen
magnum
Anterior
part
Middle
part
Posterior
part
Norma Basalis Externa

13. Anterior part
• Formed by the Bony Palate
• The anterior ¾ of the palate is formed by the palatine processes of both maxillae
(separated by the intermaxillary suture)
• The posterior ¼ is formed by the horizontal plates of both palatine bones (separated
by the interpalatine suture)
Palatine processes
of maxillary bones
Horizontal plates
of palatine bones
Interpalatine suture
Intermaxillary suture
Incisive fossa

14. Features of the anterior part
• Alveolar arch, formed by the alveolar processes of both maxillae
• Cruciform suture, separates the parts forming the hard palate.
• Incisive fossa, an anterior median depression.
• Greater palatine foramen (one on each side), on the posterior and lateral part of the
bony palate. It leads to the greater palatine canal
• Lesser palatine foramina (two small foramina) behind the greater palatine foramen.
• Vascular groove, runs forward close to the alveolar arch
• Posterior nasal spine, a median projection from the posterior border of the bony palate
Incisive fossa
Alveolar arch
Greater palatine
foramen
Lesser palatine
foraminaPosterior nasal
spine
Interpalatine
suture
Palato-maxillary
suture
Intermaxillary suture
Cruciform
suture

15. • Body of sphenoid bone
• Pterygoid process of sphenois
• Greater wing of sphenoid
• Petrous part of temporal bone
• Tympanic part of temporal bone
• Mastoid part of temporal bone
• Mandibular fossa
Body of
sphenoid bone
Petrous part
of temporal bone
Groove for cartilagenous
part of auditory tube
Tympanic part
of temporal bone
Styloid process
Mandibular
fossa
Mastoid part
of temporal bone
Greater wing
of sphenoid
Middle part
Extends from the posterior margin of hard palate
to the anterior margin of foramen magnum

16. Features:
•Vomer, a median bone forming the posterior part of the nasal septum
•Posterior nasal apertures
•Pterygoid process, formed of lateral & medial plates with the pterygoid fossa in between.
•Pterygoid hamulus
•Pterygomaxillary fissure
•Maxillary tuberosity, a rough prominence behind the last molar tooth
•Infratemporal surface of greater wing of sphenoid
Pterygoid hamulus
Posterior nasal
apertures
Vomer
Medial pterygoid
plate
Lateral pterygoid
plate
Greater wing
of sphenoid

17. Foramina to be identified:
• Foramen ovale, on the infratemporal surface of greater wing of sphenoid
• Foramen spinosum, behind the foramen ovale
• Foramen lacerum, at the apex of petrous temporal bone
• Carotid canal
• Stylomastoid foramen, between the styloid and mastoid processes.
Foramen ovale
Foramen spinosum
Foramen lacerum
Carotid canal
Stylomastoid foramen
Groove for cartilagenous
part of auditory tube

18. Posterior part
Formed mainly by the different parts of the occipital bone, surrounding the foramen magnum
Bones to be identified:
• Basilar part of occipital bone, in front of foramen magnum
• Condylar parts, one on each side of foramen magnum
• Squamous part, behind the foramen magnum
Features:
•Pharyngeal tubercle, a small
elevation on the basilar part
•Occipital condyles, on each side of
foramen magnum
•Condylar fossa, behind the occipital
condyles
•External occipital protuberance
•External occipital crest
•Inferior nuchal lines
•Superior nuchal lines
Basilar
part
Squamous part
Foramen
magnum
Pharyngeal tubercle
Occipital condyles
(condylar part)
External occipital
protuberance
Condylar fossa
Condylar canal
External occipital crest
Inferior nuchal lines
Superior nuchal lines

19. Foramina:
• Foramen magnum, the largest in the skull
• Jugular foramen, between the occipital and petrous temporal bones
• Hypoglossal canal, above the occipital condyle
• Condylar canal
Foramen
magnum
Jugular foramen
Jugular fossa
Condylar canal
Mastoid foramen

20. Norma Basalis Interna
Divided into; anterior, middle and posterior cranial fossae
Features of the anterior cranial fossa
• Frontal crest, a median ridge on the inner aspect
of frontal bone
• Cribriform plate of ethmoid bone, in the median
region of the fossa, forming the roof of the nasal
cavity. It shows a median projection called the
crista galli
• Orbital plate of frontal bone, on each side of the
cribriform plate of ethmoid.
• Body of sphenoid bone, behind the cribriform
plate
• Lesser wing of sphenoid, on each side of the
sphenoid bone.
• Anterior clinoid process The medial end of the
lesser wing
Frontal crest
Cribriform plate
of ethmoid
Orbital plate
of frontal bone
Body of sphenoid bone
Lesser wing
of sphenoid Crista galli
Anterior clinoid
process
Anterior cranial fossa
Bound posteriorly by the
lesser wings of sphenoid

21. Foramina:
• Foramen cecum, between the
crista galli and frontal crest
• Antherior ethmoidal canal, on
the lateral margin of the cribriform
plate of ethmoid
• Posterior ethmoidal canal, at the
posterolateral angle of the
cribriform plate of ethmoid.
Foramen cecum
Antherior ethmoidal
canal
Posterior ethmoidal
canal

22. Middle cranial fossa
• Bound anteriorly by the lesser wings of sphenoid and posteriorly
by the upper border of petrous temporal bone
• Narrow in the middle and expands greatly laterally
Bones to be identified;
• Body of sphenoid, in the median region
• Greater wing of sphenoid
• Squamous part of temporal bone
• Anterior surface of petrous
temporal bone
Body of
sphenoid
Greater wing
of sphenoid
Squamous part
of temporal bone
Petrous part
of temporal bone
F.
magnum

23. Features of the middle cranial fossa
Tegmen
tympani
Acruate
eminence
Trigeminal
impression
Groove for ICA Hypophyseal
fossa
Posterior
clinoid process
Foramen
lacerum
Sulcus for
optic chiasma
Anterior clinoid
process
• Hypophyseal fossa (sella turcica), a median depression on the body of sphenoid. Bound
anteriorly by the tuberculum sellae and posteriorly by the dorsum sellae. The upper end of
the dorsum sellae forms two projections (the posterior clinoid processes)
• Groove for Internal Carotid Artery,
on the lateral aspect of the body of sphenoid
• Trigeminal impression,
a depression at the apex of petrous temporal bone
• Acruate eminence, an elevation on the
anterior surface of petrous temporal bone
• Tegmen tympani (roof of the middle ear)
lies lateral to the arcuate eminence.

24. Foramina and openings in the
middle cranial fossa;
• Superior orbital fissure, a fissure
between the greater and lesser wings of
sphenoid
• Foramen rotundum, behind the
medial end of superior orbital fissure,
leads to the pterygopalatine fossa
• Foramen ovale, behind the foramen
rotundum.
• Foramen spinosum, behind the
foramen ovale
• Foramen lacerum, at the apex of
petrous temporal bone
Superior orbital fissure
Foramen rotundum
Foramen ovale
Foramen spinosum
Foramen
lacerum
Groove for greater
petrosal nerve
Groove for lesser
petrosal nerve

25. Posterior cranial fossa
Boundaries:
posterior clinoid process, upper border of
petrous temporal bone, groove for transvers
sinus, internal occipital protuberance
Bones to be identified;
• Basilar part of occipital bone, in
front of F magnum. Together with
the basilar part of sphenoid they
form the clivus.
• Condylar part of occipital bone,
on each side of F magnum.
• Squamous part of occipital bone,
behind F magnum.
• Posterior surface of petrous
temporal bone, lateral to the
occipital bone
• Mastoid part of temporal bone,
behind and lateral to the petrous
part.
Basilar part of
occipital bone
Basilar part
of sphenoid
Squamous part
of occipital bone
Petrous
temporal bone
Clivus
Condylar part
of occipital bone
Mastoid part
of temporal bone

26. Features of the posterior cranial fossa
• Internal occipital protuberance, a median
elevation on the squamous part of occipital bone
• Internal occipital crest, a median ridge
extending from the internal occipital
protuberance to the F. magnum
• Groove for transverse venous sinus, extends
from the internal occipital protuberance to the
mastoid part of temporal bone
• Sigmoid sulcus, an S-shaped sulcus extending
from the end of the groove for transverse sinus
to the jugular foramen
• Groove for superior petrosal sinus, running
along the upper border of petrous temporal bone
• Groove for inferior petrosal sinus, running
along the ptrosphenoidal fissure (between
petrous bone and occipital bone)
Internal occipital
protuberance
Internal occipital
crest
Groove for transverse
venous sinus
Sigmoid sulcus
Groove for superior
petrosal sinus
Groove for inferior
petrosal sinus

27. Foramina to be identified:
• Foramen magnum
• Jugular foramen, between the occipital
and petrous bones
• Hypoglossal canal, above the occipital
condyle
• Condylar canal, connects the codylar
fossa (seen on the norma basalis externa)
with the sigmoid sulcus
• Mastoid foramen, on the line of the
occipito-mastoid suture (opens into the
sigmoid sulcus)
• Internal acoustic meatus, on the
posterior surface of petrous bone
Foramen
magnum
Jugular foramen
Hypoglossal
canal
Condylar canal
Mastoid foramen
Internal acoustic
meatus
Foramen spinosum
Foramen ovale
Foramen
rotundum
Foramen
lacerum

28. Mandible
• Formed of a body and 2 rami
• The body is horse shoe-shaped and formed of 2
halves fused together at the symphysis menti
• The ramus forms 2 upward projections; coronoid
process anteriorly and condylar process
posteriorly
• The condylar process constitutes the head and neck
of the mandible. The small depression on the front
of the neck is called pterygoid fovea
• Angle of the mandible, the junction between the
base of the mandible (lower border) and the
posterior border of the ramus
• Mandibular notch, the concave upper border of
the ramus (the depression between the 2 processes)
Features of the outer surface of mandible
• Mental protuberance, a median elevation close
to the lower border. It forms a projection on each
side called mental tubercle
• Mental foramen, lateral to the mental
protuberance
• Oblique line, a ridge extending from the anterior
border of the ramus onto the outer surface of the
body
• Alveolar border, the upper border of the body
Head of
mandible
Neck of
mandible
Condylar
process
Mandibular notch
Oblique line
Angle of
the mandible
Mental foramen
Mental tubercle
Coronoid process
Pterygoid fovea
Ramus
B o d y
Base of
the mandible

29. Features of the inner surface of mandible
• Mylohyoid line, an oblique line on the inner
surface of the body
• Submandibular fossa, a depression below the
mylohoid line
• Sublingual fossa, a small depression above the
mylohoid line
• Superior and inferior genial tubercles, 2 small
median projections on the back of smyphysis menti
• Digastric fossa, a small depression on the base on
each side of the symphysis menti
• Mandibular foramen, on the inner aspect of the
ramus. It leads to the mandibular canal which
ends below the 2nd
premolar tooth and bifurcates
into incisive canal (continues below the incisor
teeth) and the mental canal which opens at the
mental foramen
• Lingula, a small projection of bone at the
mandibular foramen
• Mylohyoid groove, a narrow groove on the inner
surface of the ramus, from the mandibular foramen
and below the mylohyoid line.
Mylohyoid line
Submandibular fossa
Sublingual fossa
Genial tubercles
Digastric fossa
Mandibular foramen
Lingula
Mylohyoid groove