skull features with schematic diagrams

1. SKULL
View,Features
Dr.Prajkta Kulkarni
Assistant Professor,Assistant Professor,
Rachanasharir(Anatomy)
Tilak Ayurved Mahavidyalaya,Pune
email- prajktakulkarni2005@gmail.com

2. The Right Orbit –Anterior Aspect

8. SKULL
Skull – cranium with mandible.
The upper part of the cranium forms a box to enclose &
Protect the brain – calvaria
The remaining skull – facial skeleton
Facial bones – 14Facial bones – 14
Nasal – 2,maxillae – 2,zygomatic – 2,mandible –1,lacrimal-2
Palatine -2 ,inf.nasal conchae -2,vomer -1
Total no. of cranial bones – 22
Bones of calvaria – 8
Frontal -1,parietal-2,temporal-2,occipital-1,sphenoid-1,
Ethmoid-1

9. Skull viewed from –
above –norma verticalis
below – norma basalis
behind –norma occipitalis
in front - norma frontalis
from side - norma lateralisfrom side - norma lateralis
Skull cap (calvaria) – consists of –
-large part of frontal bone
- most of 2 parietal bones
- small part of occipital bone
- small part of the squamae of temporal.

10. NORMA VERTICALIS
1.Coronal suture-
joint between posterior edge of the frontal & anterior
borders of the parietal bones .
on each side of the median plane , it passes downwards
& forwards across the cranial vault.
2. Sagittal suture –
in the median plane between the interlocking upperin the median plane between the interlocking upper
borders of the two parietal bones.
3.Lambdoid suture –
unites the posterior borders of the parietal bones to
the superior border of the squamous part of occipital.
it runs downwards & forwards across the cranial vault.
meeting point of coronal & sagittal suture- bregma

11. In foetal skull ,it is site of a membrane filled gap, known as
Anterior fontanelle.
Junction of sagittal & lambdoid sutures – lambda
In foetus ,site of gap – posterior fontanelle
Parietal tuber – region of maximumconvexity of parietals.Parietal tuber – region of maximumconvexity of parietals.
Parietal foramen – present near sagittal suture ,3.5cm
In front of lambda .
Transmits a small emissory vein from the superior
Sagittal sinus within the skull.

12. NORMA OCCIPITALIS
Features –
•External occipital protuberance - it is in the lower part
of the field in the median plane.
•Superior nuchal lines – sharp ridges ,pass laterally from
the protuberance.
•Highest nuchal lines – curved ridges ,1cm above sup.•Highest nuchal lines – curved ridges ,1cm above sup.
nuchal lines. More arched than the superior nuchal lines
Commencing at upper part of the protuberance .
•Inferior nuchal line
•Asterion – meeting point of parietal,occipital &mastoid
part of temporal bone,at lower end of lambdoid suture.
Inion – point on the external occipital protuberance.

13. NORMA FRONTALIS
Upper part formed by –frontal bone ,smooth & convex
Lower part – face –irregular ,interrupted by orbits & ant.
Bony aperture of nasal cavities.
•Superciliary arch – a rounded elevation , immediately
above the medial part of each orbit.above the medial part of each orbit.
• better marked in male than in female.
•2 arches connected by median elevation –glabella
•The point where internasal & frontonasal sutures meet,
is called as the nasion.

14. Norma frontalis consists of –
Orbital opening ,anterior nasal aperture ,orbital cavity.
1.Orbital opening –
quadrangular in shape.
boundaries –
a) supraorbital margin –frontal bone .
at junction of lateral 2/3 & medial 1/3 –supraorbital notchat junction of lateral 2/3 & medial 1/3 –supraorbital notch
(foramen )
Lateral – frontal process of zygomatic bone & above
completed by zygomatic process of frontal bone.
b)Infraorbital margin – laterally – zygomatic bone
medially – maxilla
medially above – by frontal bone
below – lacrimal crest of frontal process of maxilla.

15. 2.ANTERIOR NASAL APERTURE –piriform ,(pear shaped)
wider below.
bounded by – nasal bones & maxillae .
• 2 nasal bones articulate with each other in median plane
& both with frontal bone above .
• on each side – nasal bone articulates with frontal process of
maxilla.maxilla.
lower boundary free & forms upper boundary of aperture.
•Anterior surface of maxilla can be viewed in norma frontalis.
•Anterior nasal spine – prominent sharp projection, meeting
point of 2 maxillae in lower boundary of aperture.
•Infra –orbital foramen – 1cm below infra-orbital margin of
maxilla , transmits infra-orbital nerves & vessels.

16. •Alveolar process of maxilla – contains sockets for teeth.
•Zygomatic process of maxilla – projection from upper &
lateral part of the anterior surface of the bone.
Articulates
With the zygomatic bone at zygomatico-maxillary suture.
Its lower border meets the body of the bone.
•Frontal process of maxilla forms lower part of the medial
margin of orbital opening & reaches frontal bone.
•Prominence of cheek – by zygomatic bone.

17. 3.ORBITAL CAVITY-
Contains eyeballs , associated vessels,nerves,lacrimal
Apparatus & considerable amount of fat.
Shape – pyramidal
Long axis directed backwards & medially.
Structure - roof,floor,medial & lateral walls ,a base & apex.
1.Roof – mainly orbital plate of the frontal .1.Roof – mainly orbital plate of the frontal .
post.part of roof by undersurface of lesser wingof
sphenoid.
the optic canal lies between two roots of lesser wing &
bounded medially by body of sphenoid.
•Anterolaterally ,a deep fossa – lacrimal fossa – for the
orbital part of the lacrimal gland .

18. •At posterior end of the junction of roof & medial wall –optic
canal ( foramen),through which orbit & middle cranial fossa
communicates.
•Close to the superior,medial ,lower margins of the canal into
orbit ,a common tendinous ring is attached to orbital walls
for origin of certain muscles of eyeball.
2.Medial wall – related to anterior part of sphenoidal sinus &2.Medial wall – related to anterior part of sphenoidal sinus &
forms its lateral wall.
• limited in front by lacrimal crest of frontal process of maxilla
behind this crest ,there is lacrimal groove for lacrimal sac.
• the lacrimal groove communicates with nasal cavity through
nasolacrimal canal ,which is 1cm long & contains the
nasolacrimal duct.orbital plate of ethmoid bone-major part
of medial wall.

19. 3. Inferior wall – formed by orbital surface of maxilla &
antero-laterally by zygomatic bone .
• at postero-medial corner –by orbital process of palatine
bone.
•Inferior orbital fissure – transmits zygomatic nerve ,infra
orbital vessels ,maxillary nerve.
this fissure is bounded by greater wing of sphenoid above ,
below by maxilla & orbital process of palatine bone.below by maxilla & orbital process of palatine bone.
laterally by zygomatic bone or zygomaticomaxillary suture.
4.Lateral wall –
behind by orbital surface of greater wing of sphenoid &
orbital surface of frontal process of zygomatic bone ant.ly.
•Supraorbital fissure – bounded above by lesser wing of the
sphenoid bone ,below by greater wing ,medially by its body.

20. Contents – lacrimal & frontal nerve , meningeal branch of
lacrimal artery , occulomotor nerve.
NORMA LATERALIS
Limited by temporal lines ,arching upwards & backwards
From zygomatic process of frontal bone , across coronalFrom zygomatic process of frontal bone , across coronal
Suture to parietal bone.
Upper temporal lines fade away . lower lines beccome
Prominent-curves downwards & forwards across squamous
Part of temporal bone just above base of mastoid.this part
Is called supramastoid crest. Becomes continuous with
Posterior root of zygomatic process.

21. Temporal fossa – bounded by zygomatic arch,temporal line &
Frontal process of zygomatic bone. temporalis muscle is
Attached to its floor.
Pterion – H shaped arrangement of sutures can be seen in the
Anterior part of the fossa.
Horizontal limb of H – formed by suture between antero-inf.
Angle of parietal bone & upper border of greater wing of theAngle of parietal bone & upper border of greater wing of the
Sphenoid.
4 bones unite with each other at this region – frontal,parietal,
Sphenoid , squamous part of temporal bone.
Important landmark for surgeons.
Lies 4cm above zygomatic arch ,3.5cm behind frontozygomatic
Suture.

22. anterior wall of fossa –formed by temporal surface of the
Zygomatic bone,adjoining part of greater wing of sphenoid
& a small portion of frontal bone.
It is between fossa & orbit.
This fossa communicates with infratemporal fossa through
Gap ,separating zygomatic arch from side of skull.
ZYGOMATIC ARCH –ZYGOMATIC ARCH –
Formed by temporal process of zygomatic bone & the
Zygomatic process of temporal bone.
Anteriorly arch is crossed obliquely downwards &
Backwards by zygomatico – temporal suture.
The zygomatic process of temporal bone widens posteriorly
As it approaches squamous part & divides into anterior &
Posterior roots.ant.root passes medially in front of the

23. Mandibular fossa ,into smooth articular tubercle.
The posterior root passes backwards ,lateral to the fossa &its
Upper border continous with supramastoid crest of temporal
Bone.
EXTERNAL ACOUSTIC MEATUS –
Opens immediately below posterior part of posterior root of
Zygoma.margins below & in front roughened for attachmentZygoma.margins below & in front roughened for attachment
Of cartilage.
Upper margin & upper part of posterior margin are formed by
Squamous part of temporal bone .the rest is formed by the
Tympanic part of temporal bone.
Suprameatal triangle – bounded by above – supramastoid
Crest.in front – postero-superior margin of orifice of meatus.

24. Behind a vertical line drawn as a tangent to the curve of the
Posterior margin of meatal orifice.
This triangle forms lateral wall of mastoid antrum .this space
Is important to surgeons.
MASTOID PART OF TEMPORAL BONE – present behind the
Meatus. Articulates with posteroinferior part of parietal boneMeatus. Articulates with posteroinferior part of parietal bone
At parieto-mastoid suture.
Articulates with squamous part of occipital bone at the
Occipito-mastoid suture.
•Asterion
MASTOID PROCESS – strong projection from lower part of
Mastoid ,lies below & behind extenal acoustic meatus.

25. MASTOID FORAMEN –pierces bone above base of mastoid
Process near or on occipito-mastoid suture. Transmits the
Emissory vein from sigmoid sinus.
STYLOID PROCESS – elongated projection in front of mastoid
Process.directed downwards,forwards ,medially.
Gives origin to 3 muscles – stylohyoid , styloglossus &
Stylopharyngeus.Stylopharyngeus.
STYLOHYOID LIGAMENT – from its extremity to the lesser
Cornu of the hyoid bone.downwards & forwards .

26. NORMA BASALIS
Inferior surface of base of skull.
It consists of 3 parts – anterior,intermediate,posterior.
Anterior part- upto posterior limit of hard palate.
Intermediate – upto transverse line across ant. Margin of the
foramen magnum.
Poterior part- rest of norma basalis .Poterior part- rest of norma basalis .
•Anterior part – bony palate & alveolar arch.
formed by palatine processes of maxillae & horizontal parts
Of palatine bones.posteriorly ends in free margin with post.
Nasal spine in midline.
Palatine crest can be seen close to this margin.
Greater palatine foramina lie close to lateral border of hard
Palate ,transmit greater palatine vessels & nerves.

27. Lesser palatine foramina – 2 on each side ,just behind the
Greater foramina ,transmit corresponding vessels & nerves.
•Incisive fossa – a depression ,behind central incisor teeth.
•Lateral wall of fossa shows lateral incisive foramen.this
foramen transmits naso-palatine nerve & branches of the
greater palatine vessels.
•Alveolar arch – horse –shoe shaped ,provides sockets for•Alveolar arch – horse –shoe shaped ,provides sockets for
teeth of jaw.
•Intermediate part – median structures include posterior
Border of vomer,inferior surface of body of sphenoid ,basilar
Part of occipital bone .
The upper border of vomer diverges into 2 alae .
Vomerovaginal canal is present between body of sphenoid&
Vaginal process of medial ptrygoid plate.

28. Inferior surface of vaginal process presents a groove ,called
Palatino-vaginal canal containing pharyngeal vesssels & the
Nerves.
•Intermediate area includes –
1.medial & lateral pterygoid plates
2.infrea-temporal surface of greater wing of sphenoid
3.squamous,petrous & tympanic - temporal bone3.squamous,petrous & tympanic - temporal bone
4.scaphoid fossa – posterior border of medial plate shows it
in its upper part.
traced below, the border shows lateral projection ,hamulus
5. middle of posterior border shows processus tuberius
which supports medial end of auditory tube.
6. posterior boder of lateral plate is free . In midddle ,shows
a bony process ,connected to spine of sphenoid.

29. 7. Foramen ovale – close to upper end of posterior margin
of lateral pterygoid plate. Transmits 2 roots of the
mandibular nerve ,accessory meningeal artery , emissory
vein .
8. Foramen spinosum – postero-lateral to foramen ovale.
transmits middle meningeal artery ,branch of trunk of
mandibular nerve .
9.Zygomatic process of squamous temporal shows a tubercle9.Zygomatic process of squamous temporal shows a tubercle
separating anterior & posterior roots.
10.Mandibular fossa – shows anterior articular part & post.
non-articular part. Articular part joins head of mandible
separated by a disc forming temporo-mandibular joint.
the non-articular part of fossa is separated from joint by
a part of parotid gland.

30. 11.Squamotympanic fissure is in between articular & non-
articular parts of fossa. Tegmen tympani divides this
fissure into petrosquamous & petro-tympanic fissure.
the later fissure transmits chorda tympani nerve,ant.tym.
branch of maxillary artery & anterior ligament of malleus
12.The lateral border of tympanic plate forms antero-inferior
margin of ext. Acoustic meatus.margin of ext. Acoustic meatus.
13.Apex of petrous temporal is separated from body of the
sphenoid by a irregular canal ,foramen lacerum.transmits
meningeal branches of asc.pharyngeal artery& emissory
vein from cavernous sinus.
14. Carotid canal – transmits internal carotid artery.

31. •POSTERIOR PART -
1.foramen magnum – oval,wider behind tthan in front.
3.5 cm-ant.post. , 3cm transverse.
• alar ligament from dens is attached to tubercles on the
occipital condyles on each side of foramen.
foramen has ant.small & post. Large part due to alar lig.
small ,ant. part- apical ligament, membrana tectoria
large ,post.part- lower end of medulla oblongata & thelarge ,post.part- lower end of medulla oblongata & the
meninges .spinal roots of accessory nerve
4th part of vertebral artery,ant.post.spinal
arteries,tonsil of cerebellum
Ant.post.margins – ant.& post atlanto-occipital membrane.
•Ext .occi.crest & protu.- attach. to upper end of lig.nuchae.
•Occipital condyles -2 ,articulate with upper surface of lateral
mass of atlas.

32. •Hypoglossal canal – above ant.part of occipital condyle.
hypoglossal nerve ,meningeal branch of asc. Pharyngeal art.
•Jugular foramen – large ,transmits inf. Petrosal sinus , the
pharyngeal,vagus,accessory nerves , meningeal branch of
asc. Meningeal artery ,internal jugular vein (sup. Bulb)
•Mastoid canaliculi – in the lateral wall of jugular fossa. It
transmits auricular branch of vagus nerve.
•Stylomastoid foramen – midway between styloid & mastoid
processes ,transmit facial nerve & stylomastoid artery.

33. ANTERIOR CRANIAL FOSSA-
Lodges frontal lobes .shows cribriform plate ,orbital plates
Of frontal bone , lesser wing of sphenoid.
1.Cribriform plate – roof of nasal cavity. Shows many small
openings for olfactory nerves from the nasal mucosa to
olfactory bulbs. Median projection named crista galli,is
present ,gives attachment to falx cerebri. The foramen
caecum is present between frontal crest & crista galli.caecum is present between frontal crest & crista galli.
2.Orbital plate of frontal bone –form roof of orbit & the
ethmoidal sinuses.
3. Lesser wing of sphenoid – medial end of posterior margin
shows anterior clinoid processes.attach. To ant. Ends of
tentorium cerebelli.

34. MIDDLE CRANIAL FOSSA –
Contain hypophysis cerebri & temporal lobes.
•Sulcus chiasmaticus a groove on each side of optic canal
Optic chiasma lie above it.
•Optic canal – transmits optic nerve & ophthlmic artery.
•Sella turcica – like saddle . has tuberculum sellae , the
hypophyseal fossa , dorsum sellae.hypophyseal fossa , dorsum sellae.
Hypophyseal fossa contain pituitary gland.
Dorsum sellae show posterior clinoid processes.
•Superior orbital fissure – transmits lacrimal, frontal & the
trochlear nerves , lacrimal branch of middle mening. Art.
& mening. Branch of ophthalmic artery, sup. Ophthalmic
vein ,sup. & inf. Rami of oculomotor nerve,abducens & the
Nasociliary nerve.

35. •Foramen rotundum – behind medial end of sup.orbital fiss.
transmits maxillary nerve .
•Foramen ovale
•Foramen spinosum
•Trigeminal impression – lodges the same named ganglion.
postero-lteral to foramen lacerum.
Tegmen tympani – shows lateral foramen – lesser petrosal n.Tegmen tympani – shows lateral foramen – lesser petrosal n.
medial foramen – greater petrosal nerve
•Foramen lacerum
POSTERIOR CRANIAL FOSSA-
Deepest, cerebellum, pons ,medulla oblongata.
Foramen magnum.
Clivus – sloping surface ,in front of foramen magnum.

36. •Internal occipital crest – attachment to falx cerebelli.
•Internal occipital protuberance –place where falx cerebri,
falx cerebelli ,tentorium cerebelli .
Internal acoustic meatus – a bony canal ,transmits facial & the
vestibulo-cochlear nerves, labyrinthine artery.vestibulo-cochlear nerves, labyrinthine artery.