Bones of Skull (Human Anatomy)

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DR RAI M. AMMAR MADNIDR RAI M. AMMAR MADNI

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DR RAI M. AMMAR MADNIDR RAI M. AMMAR MADNI

• The skull, the body’s most complex bony structure,
• formed by two sets of bones;
Cerebral Cranium:(Larger, postero-superior part)
• contains and protects the brain,
• provides attachment sites for some head and neck muscles.
 Facial Cranium:(Smaller, antero-inferior part)
• Provides framework of face, sense organs and teeth
• Provides openings for the passage of air and food
• Anchor the facial muscles of expression
The Skull
Bones are joined by suturesBones are joined by sutures
Only the mandible is attached by a freelyOnly the mandible is attached by a freely
movable jointmovable joint

 Bones of Cerebral cranium / Calvaria (8)
 Single bones(4): include
frontal bone ,
ethmoid bone ,
sphenoid bone ,
occipital bone.
 Paired bones (4): include
temporal bones
parietal bones
 Middle Ear Ossicles (6)
malleus (2)
incus (2)
stapes (2)
The Skull (Cranium)

Frontal bone
Zygomatic bone
Nasal bone
Maxilla
Mandible
Sphenoid bone
parietal bone
Temporal bone
Occipital bone

 Bones of facial cranium (15)
 Single bones (3) include
mandible,
vomer,
hyoid bone.
maxilla,
nasal bone,
lacrimal bone,
palatine bone,
zygomatic bone,
inferior nasal concha.
The Skull (Cranium)

Facial bones - Mnemonic
Virgil Can Not Make My Pet Zebra
Laugh!
 Vomer Conchae Nasal Maxilla Mandible Palatine Zygomatic
Lacrimal
a mind memory and/or learning aid.

 from above (norma verticalis)
 from below (norma basalis),
 from the side (norma lateralis),
 from behind (norma occipitalis),
 from the front (norma frontalis).
Exterior of SkullExterior of Skull (Terminology)(Terminology)

Bones of the SkullBones of the Skull ( Anterior view)( Anterior view)

Bones of the SkullBones of the Skull ( Lateral view)( Lateral view)
Temporal fossaTemporal fossa
PterionPterion

SUTURES
 Suture - A line formed by
the junction of two skull
bones
CORONAL SUTURE: juction
between frontal & parietal bones.
SAGITTAL SUTURE: juction
between two parietal bones.
LAMBDOIDAL SUTURE: juction
between parietal bones & occipital
bone.
SQUAMOUS SUTURE: juction
between parietal & temporal bones.

FONTANELLES
Anterior fontanelle (soft spot.) –
• The junction where the two frontal and two parietal
bones meet.
• The anterior fontanelle remains soft until about 2 years
of age.
Posterior fontanelle –
• The junction of the two parietal bones and the occipital
bone.
• The posterior fontanelle usually closes first, before the
anterior fontanelle, during the first several months of an
infant's life.

BREGMA:-
Meeting point between the
coronal & sagital sutures.
LAMBDA:-
Meeting point between the
sagittal and lambdoid sutures.

Bones of the SkullBones of the Skull ( Interior view)( Interior view)

Base of skull formsBase of skull forms
three fossaethree fossae
 Anterior cranial fossa
 Middle cranial fossa
 Posterior cranial fossa
Internal view of base of skull

Internal view of base of skull
Figure 7.4b

Anterior cranial fossa
Formed by orbital
part of frontal bone,
cribriform plate of
ethmoid, and lesser
wings of sphenoid
 Structures:
 frontal crest
 foramen cecum
 crista galli
 cribriform plate
 cribriform foramina

Middle cranial fossa
 Formed by the body
and greater wings of
sphenoid, petrous part
of temporal
 Structures:
 body of sphenoid bone
 hypophysial fossa
 optic canal
 anterior clinoid process
 tuberculum sellae
 dorsum sellae
 posterior clinoid process
 sella turcica

Middle cranial fossa
 carotid sulcus
 superior orbital fissure
 foramen rotundum
 foramen ovale
 foramen spinosum
 sulcus for middle meningeal
artery
 foramen lacerum
 internal opening of carotid
canal
 trigeminal impression
 tegmen tympani

Posterior cranial fossa
 Formed by occipital and the
petrous part of temporal
 Structures:
 foramen magnum
 clivus
 internal opening of
hypoglossal canal
 internal occipital protuberance
 internal occipital crest
 sulcus for transverse sinus
 sulcus for sigmoid sinus
 jugular foramen
 internal acoustic pore
 internal acoustic meatus

24Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.9
Bones of the Skull ( Inferior view)

Bones of the Skull (inferior view)
alveolar arch
bony palate
median palatine
suture
incisive foramina
incisive canal
greater palatine
foramen
posterior nasal
apertures
pterygoid process

Bones of the Skull (inferior view)
occipital condyle
external opening of
hypoglossal canal
external opening of
carotid canal
styloid process
stylomastoid foramen
mandibular fossa
articular tubercle

 Cranium is divided into cranial vault and the base
 Internally, prominent bony ridges divide skull into
distinct fossae. The skull contains smaller cavities
 Middle and inner ear cavities – in lateral aspect of
cranial base
 Nasal cavity – lies in and posterior to the nose
 Orbits – house the eyeballs
 Air-filled sinuses – occur in several bones around
the nasal cavity
 The skull contains approximately 85 named openings
 Foramina, canals, and fissures
 Provide openings for important structures
 Spinal cord
 Blood vessels serving the brain
 12 pairs of cranial nerves
Overview of Skull GeographyOverview of Skull Geography

FRONTAL BONE
Forms the forehead and roofs of the
orbits
Forms superciliary arches
Internally, it contributes to the
anterior cranial fossa
Contains frontal sinuses
Articulates posteriorly with the
parietal bones via the coronal suture

FRONTAL BONE
. Major markings:-
 Supra-orbital margin :arch of
bone above he orbital opening
 Superciliary arch :the ridge of
bone above the orbital margin
glabella :midline point between
the paired superciliary arches
supraorbital notch :notch in the
supra-orbital margin

OCCIPITAL BONE
Forms the posterior portion of the
cranium and posterior cranial fossa
Articulates with the temporal bones and
parietal bones
Foramen magnum located at its base and
communicates with the vertebral canal

OCCIPITAL BONE
Consists of a Squamous, Basilar, and
Two Lateral (Condylar) Portions
Major markings:-
 External occipital protuberance :
 Superior nuchal lines :low
transverse ridge on the external
surface of squamous part
 Inferior nuchal lines
 Occipital condyles
Anteriorly:-
 Hypoglossal Canal (l2th C. Nerve)
 Condylar Canal (Emissay Vein )

Parietal Bones and Sutures
Form superior and lateral parts of skull
Four important sutures of the cranium
 Coronal suture – Junction between frontal and
parietal bones anteriorly
 Squamous suture – Junction between parietal
and temporal bones inferiorly
 Sagittal suture – Junction between right and left
parietal bones superiorly
 Lambdoid suture – Junction between the
parietal and occipital bone posteriorly

PARIETAL BONES
Cover much of the top
and sides of the brain
Major markings:-
Superior temporal line:
attachement point of the
temporal fascia.
Iferior temporal line :
attachment point for the
temporal muscle

Temporal Bones
 Lie inferior to parietal bones
 Form the inferolateral portion of the skull
 Term “temporal”
 Comes from Latin word for time
 Specific regions of temporal bone
o Squamous,
o temporal,
o petrous,
o Mastoid.

TEMPORAL BONE
Major markings:-
 Squamous (flat portion of the
bone that projecting superiorly
toward the parietial bone )including
its Zygomatic Process
Tympanic Bone (External
Auditory Cana) around the ear
Mastoid (Mastoid Air Cells )
behind the ear
Petrous Bone (surrounds the
inner ear), containing Otic Labyrinth
and Internal Auditory Canal (IAC )
 Styloid Process

Major Openings:-
 Stylomastoid foramen
 Jugular foramen, (Int
Jugular vein, 9th, 10th,
& 1 1th Cranial Nerves)
 External auditory
meatus,
 Internal auditory
meatus
 Carotid canal
(Internal Carotid Artery )
TEMPORAL BONE

The Sphenoid Bone
Butterfly-shaped bone that forms part of
the floor of the anterior, middle, and
posterior cranial fossae.
“Keystone” of the cranial floor because it
articulates with all the other cranial
bones.
Consists of a central body, greater wings,
lesser wings, and pterygoid processes

The Sphenoid Bone
Figure 7.6a, b

SPHENOID BONE
Body:
 central part of the sphenoid
bone
 sphenoid air sinuses
Three pairs of
projections:
Lesser Wings, the more superior
(contains Optic Canal )
Greater Wings , the intermediate
(contains Foramina Ovale,
Rotundum, and Spinosum )
Pterygoid Processes, the most
inferior

Sella turcica:-
 Resembles “Turkish
Saddle”
 Depression on the
superior surface of the
body of sphenoid bone
 Protective,bony
housing around the
Pituitary Gland.
.
SPHENOID BONE

Parts of Sella Turcica
 Dorsum Sellae: the back wall
 Hypophysial Fossa: central
depression in which pituitary gland sits.
 Posterior Clinoid Proces: samll
lateral extension
 Tuberculum Sellae: horizontal ridge
, along the anterior portion
Major Openings:-
foramina rotundum,
ovale,
spinosum;
optic canals;
superior orbital fissure
SPHENOID BONE

ETHMOID BONE
Lies between nasal and sphenoid
bones
Forms most of the medial bony region
between the nasal cavity and orbits,
the ethmoid sinuses

.ETHMOID BONE
Major markings:-
• Horizontal Cribriform Plate; (
passage olfactory nerve)
• Two Lateral
Masses( Labyrinths);
• Perpendicular Plate Ethmoidal
Labyrinths consist of Air Cells and
• Superior and Middle Nasal
Conchae,
• Uncinate Process (one on each
side)
• Crista Galli, for the attachment
of FaIx Cerebri
• Orbital Plate forms the medial
wall of the respective eye

.Table of Foramina in Skull
Bone Location Foramen
frontal - supraorbital foramen
frontal anterior cranial fossa foramen cecum
ethmoid - foramina of cribriform plate
ethmoid anterior cranial fossa anterior ethmoidal foramen
ethmoid anterior cranial fossa posterior ethmoidal foramen
sphenoid - optic canal
sphenoid middle cranial fossa superior orbital fissure
sphenoid middle cranial fossa foramen rotundum
maxilla -
incisive foramen/
incisive canals
palatine - greater palatine foramen
palatine and
maxilla
- lesser palatine foramina

sphenoid and
maxilla
- inferior orbital fissure
maxilla - infraorbital foramen
sphenoid middle cranial fossa foramen ovale
sphenoid middle cranial fossa foramen spinosum
sphenoid - pterygoid canal
sphenoid and
palatine
- sphenopalatine foramen
sphenoid, temporal,
and occipital
middle cranial fossa
foramen lacerum
(or carotid canal
temporal posterior cranial fossa internal acoustic meatus
temporal - stylomastoid foramen

temporal - mastoid foramen
temporal - petrotympanic fissure
occipital and
temporal
posterior cranial fossa jugular foramen
occipital - hypoglossal canal
occipital - condylar canal
occipital posterior cranial fossa foramen magnum
parietal - parietal foramen
mandible - mental foramen
mandible - mandibular foramen
zygomatic - zygomaticofacial foramen
zygomatic - zygomaticotemporal forame

Wormian Bones
 Tiny irregularly shaped bones that
appear within sutures

 Single bones (3): include
 mandible,
 vomer,
 hyoid bone.
 maxilla,
 nasal bone,
 lacrimal bone,
 palatine bone,
 zygomatic bone,
 inferior nasal concha.
Bones of facial cranium

Mandible
U-shaped bone forming the lower jaw
The largest and strongest facial bone
Composed of two main parts
Horizontal body
Two upright rami

Mandible
Figure 7.8a
•Major markings:-
•Body: the anterior part of the
mandible
• Rami: the angled portion
that joins the posterior portion
of body
•Condylar Process: posterior
extension of ramus
•Coronoid Process: anterior
extension of the ramus
•Mental Symphysis: union
point of the two halves

Mandible
•Mental Foramen: transmits the
mental neurovascular bundle
•Alveolar Process: where the
teeth are embedded
•Mandubular Condyle: rounded
head of condylar process ,
articulate with madibular fossa of
the temporal bone.
•Mandibular Notch: concavity
between codylar and coronoid
process

Maxillary Bones
Second Largest Facial
bone, forming the midface
Articulate with all
other facial bones
except mandible
Contain maxillary
sinuses – largest
paranasal sinuses
Forms part of the
inferior orbital fissure

Maxillary Bones
Major markings:-
 Body
 Four Processes
• Zygomatic: projects toward the zygomatic
bone
• Frontal: toward the frontal bone
• Alveolar : inferior extension that contain
sockets for teeth
• Palatine: form hard plate
 Incisive Foramen : passageway for nasopalatine
vessels

Other Bones of the Face
Zygomatic bones
Form lateral wall of orbits
Nasal bones
Form bridge of nose
Lacrimal bones
Located in the medial orbital walls
Palatine bones
Complete the posterior part of the hard
palate

Other Bones of the Face
Vomer
Forms the inferior part of the nasal
septum
Inferior nasal conchae
Thin, curved bones that project medially
form the lateral walls of the nasal cavity

Palatine Bones
•Horizontal and Vertical portions
•Irregularly shaped (L-shaped) bones forming the;
o posterior part of the hard palate,
o the lateral wall of the nasal fossa between the
medial pterygoid plate and the maxilla &
o the posterior part of the floor of the orbit.
o The horizontal plates form the posterior part of
hard palate, separating the nasal cavity from oral
cavity.

Palatine Bones
•Horizontal and Vertical portions

Zygomatic Bones
Major markings:-
 Body
 Three Processes
• Frontal
• Temporal
• Maxillary

Nasal Bones
 Thin bones that form
part of the bridge of the
nose

 A roughly triangular,
single, thin bone,
 Joins with the
perpendicular plate of
ethmoid to form bony
septum that divides the
nasal cavity into right and
left.
Vomer Bone

Lacrimal Bones
 Anterior portion of the
medial wall of the orbit .
Lacrimal fossa;
depression at the junction
of the lacrimal and maxilla
bones that hold the lacrimal
sac.

INFERIOR NASAL CONCHAE
Thin bone, extends into
nasal cavity from the
maxilla on each side

Special Parts of the Skull
Orbits
Nasal cavity
Paranasal sinuses
Hyoid bone

Orbits
pyramid-shaped paired cavities
 Base: supraorbital notch
infraorbital foramen
 Apex: optic canal
 Walls
 Superior:
fossa for lacrimal gland
 Medial:
fossa for lacrimal sac
 Inferior:
infraorbital fissure
 infraorbital groove
 infraorbital canal

Bony nasal cavity
 Roof: cribriform plate of ethmoid
 Floor: bony palate
 Lateral wall
 Three nasal conchae
(superior, middle and inferior)
 Nasal meatus : underlying
each concha (superior, middle
and inferior)
 Sphenoethmoidal recess
above superior nasal concha
 Anterior ―piriform aperture
 Posterior ―posterior nasal
aperture communicates with
pharynx

Paranasal Sinuses
 Air-filled sinuses,lined with mucous
membrane
 Located within
Frontal bone
Ethmoid bone
Sphenoid bone
 Maxillary bones Secrete mucous into nasal cavity
 Lighten the skull
 Resonate the voice

Paranasal sinuses
Frontal sinus
 Lies in frontal bone, deep to superciliary arch
 Drain to anterior part of middle meatus

Maxillary sinus
 Largest paired
sinus, lie in the
body of maxilla;
 Opening into
middle nasal
meatus

 Ethmoidal cellules
 Lie in ethmoidal bone,
 Large number of air cells,
divided into anterior, middle
and posterior groups
 Anterior and middle, groups
drain into middle nasal
meatus, while posterior group
drains into superior nasal
meatus
 Sphenoidal sinus
 Lies in body of sphenoid bone
 Drain into sphenoethmoidal
recess

HYOID BONE
Small & U-shaped bone
located between the
mandible and larynx.
Made of 5 parts:-
-Body : central portion
-2 Greater horns:
posterior extension from body
-2 Lesser horns:
samll superior extension from the
body

malleus
incus
stapes
Middle Ear Ossicles

MalleusMalleus
 Two main parts:
 Manubrium- adheres
to the tympanic
membrane,
 Head- articulates with
the incus.
 Also has two
processes: one anterior
and one lateral

IncusIncus
3 principal parts:
 body
 two processes ( short
and long).
 Head articulates with
head of the malleus
 End of the long process
(lenticular process)
articulates with head of
the stapes.
 Short process attached to
the cavity wall.

StapesStapes
 looks like a stirrup.
 four components:
• footplate,
• two crura (posterior
and anterior),
• head.
• The head articulates
with incus.
• footplate covers the
oval window.

The Fetal Skull
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 The skull at birth is large
in proportion to rest of
the skeleton ―1/4
(adult 1/7)
 The facial portion equals
about one eight that of
the cranium in size,
whereas in adult it is
one half (1/2)
 Many bones consist of
more than one piece
Figure 5.13

The Fetal Skull
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Cranial frontanelles ―unossified membrane between
the bones at the angles of parietal bones
• Allow the brain to grow
• Convert to bone within 24 months after birth
• Anterior frontanelle ―closes during middle of 2nd year
• Posterior frontanelle ―closes by the end of 2nd month
after birth
• Mastoid fontanelle
• Sphenoidal fontanelle
Figure 5.13

The Axial Skeleton Throughout Life
 Membranous bones begin to ossify in second
month of development
 Bone tissue grows outward from ossification
centers
 Many bones of the face and skull form by
intramembranous ossification
 Endochondral bones of the skull
 Occipital bone
 Sphenoid
 Ethmoid bones
 Parts of the temporal bone

Bones of Skull (Human Anatomy)

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Bones of Skull (Human Anatomy)