The SkullThe skull is composed of several separate
bones (22 bones) united at immobile joints
called sutures.
The connective tissue between the bones
is called a sutural ligament
The upper part of the cranium is The vault
The base of the skull is the lowest part of the cranium
The skull bones are made up of
External and internal tables of compact bone separated
by a layer of spongy bone called the diploic bones
The bones are covered on the outer and inner surfaces
with periosteum.
Only one moveable bone, the mandible which is
united to the skull by the mobile
Temporomandibular Joint
The bones of the skull can be divided into:
1- Bones of the cranium (contain the brain)
2- Bones of the face
A) The cranium consists of the
following bones
two of which are paired :
Frontal bone: 1
Parietal bones: 2
Occipital bone: 1
Temporal bones: 2
Sphenoid bone: 1
Ethmoid bone: 1
B)The facial bones consist of
the following
two of which are single:
Zygomatic bones: 2
Maxillae: 2
Nasal bones: 2
Lacrimal bones: 2
Vomer: 1
Palatine bones: 2
Inferior conchae: 2
Mandible: 1
Norma Frontalis
It is the anterior aspect of the skull
Made of three parts
1-Upper part: Forehead; made of
the frontal bone
2-Middle part: contains 3 caviteis;2
orbital & 1 nasal
3-Lower part: formed by the upper
& lower jaws
1- Frontal eminence: the most prominent
areas on either side of the forehead
2-The superciliary arches
:Elevated ridges above the medial
parts of the sup. Orbital margins
3-supraorbital notch, or
foramen: located on junction
between the medial 1/3 and the
lateral 2/3. transmits the
supraorbital n. & vessels
4-Glabela:an area above the root
of the nose Between the 2
superciliary arches
5-Nasion:a point where the
frontonasal & interanasal
sutures meet
6-The nasal bones: form
the roof of the nose
The orbital margins are bounded by:
A-The frontal bone :superiorly
B-The zygomatic bone :laterally
C- The maxilla: inferiorly
D-The processes of the maxilla and
frontal bone :medially
7-The zygomatic bones has:
a-Frontal processes: articulates with
frontal bone
b-Temporal processes: articulates with
zygomatic process of the temporal bone
to form the zygomatic arch
c- maxillary processes: articulates with
the maxillary bone
d- orbital plate: shears in the formation
of the floor and lateral wall of the orbit
a-Frontal processes:
b-Temporal
processes:
c- maxillary processes
d- orbital plate
The zygomatic bone
The parietal bones form the
sides and roof of the cranium.
The skull is completed at the side
by the
1-Squamous part of the occipital
bone
2-Parts of the temporal bone
The squamous
Tympanic
Mastoid process
Styloid process
3-Zygomatic process
4- The greater wing of the
sphenoid
Note the position of the external
auditory meatus.
The ramus and body of the
mandible lie inferiorly.
.
Norma lateralis
Identify
the superior and inferior temporal
lines, which begin as a single line from
the posterior margin of the zygomatic
process of the frontal bone and diverge
as they arch backward.
The upper temporal line gives
attachment for the temporal fascia
The lower temporal line is for the
attachment of temporalis muscle
The supramastoid crest
The zygomatic arch: formed
of the temporal process of
The zygomatic process of temporal
bone and the zygomatic process of
temporal bone (its lower border And
inner surface give attachment to the
masseter muscle
The pterion is the thinnest part of the
lateral wall of the skull. it overlies the
anterior division of
The middle meningeal artery and vein
Pterion: is an area located on the floor of
the temporal fossa
Where 4 bones meet at an H-shaped
structure
The 4 bones are
1-freontal
2- parietal
3-squamous part of temporal bone
4-greater wing of sphenoid
Epidural bleeding
The temporal fossa lies below the
inferior temporal line
The infratemporal fossa
lies below the infratemporal crest on
the greater wing of the sphenoid
The zygomatic arch divides the lateral
side of the Skull into
The temporal fossa & The
infratemporal fossa
The temporal fossa
Boundries
Above and behind: the superior temporal line
Below: The zygomatic arch
Anteriorly: the frontal process of zygomatic
bone
Infratemporal fossa
Anterior wall: back of the maxilla
Medial wall: lateral pterygoid plate
Roof: infratemporal surface of the
greater wing Of sphenoid bone
Lateral wall: ramus of mandible
Communications
Temporal fossa: through the gap deep to
the zygomatic arch
Orbit: through the inferior orbital fissure
Pterygo-polatine fossa : through the
pterygo-maxillary fissure
The pterygomaxillary fissure is
a vertical fissure that lies within the
fossa between the pterygoid
process of the sphenoid bone and
back of the maxilla. It leads
medially into the pterygopalatine
fossa.
The inferior orbital fissure
is a horizontal fissure between the
greater wing of the sphenoid bone
and the maxilla.
It leads forward into the orbit.
The pterygopalatine fossa
Is a small space behind and below
the orbital cavity.
It communicates
laterally :with the infratemporal
fossa through the pterygomaxillary
fissure
Medially: with the nasal cavity
through the sphenopalatine
foramen
superiorly :with the skull
through the foramen rotundum
anteriorly :with the orbit through
the inferior orbital fissure
Superior View of the Skull
(Norma Verticalis)Anteriorly
the frontal bone articulates with the
two parietal bones
AT THE CORONAL
SUTURE
The two parietal bones articulate in
the midline
AT THE SAGITTAL
SUTURE
lambdoid
sutures
Above The posterior parts of the two
Parietal bones with the intervening
sagittal suture
Below, the parietal bones articulate with the
squamous part of the occipital bone
at the lambdoid suture.
On each side the occipital bone
articulates with the temporal bone.
In the midline of the occipital bone is
a roughened elevation called
The external occipital protuberance
which gives attachment to muscles
and the ligamentum nuchae
Posterior View of the Skull
On either side of the protuberance the
superior nuchal lines extend laterally
toward the temporal bone.
The middle cranial
fossa is separated from
the posterior cranial
fossa By
The petrous part of
the temporal bone
1-Anterior
2-Middle
3-Posterior
Base of the Skull
The interior of the base of the skull is
divided into three cranial fossae:
The anterior cranial fossa
is separated from
the middle cranial fossa
By
The lesser wing of the
sphenoid
2-M
idd
le
3-Posterior
1-Anterior
Contains the frontal lobes of
the cerebral hemispheres
Anterior Cranial Fossa
It is bounded
Anteriorly: by the inner surface of the
frontal bone
In the midline: a crest galli for the
attachment of the falx cerebri.
Posteriorly :the lesser wing of the
sphenoid bone
Note: The medial end of the lesser wing of
the sphenoid forms
The anterior clinoid process
gives attachment to the
Tentorium cerebelli.
The floor of the fossa is formed by:
Laterally :orbital plates of the frontal bone
Medially: by the cribriform plate of the
ethmoid
The crista galli is a sharp upward
projection of the ethmoid bone in the
midline for the attachment of
The falx cerebri.
formed by:
the body of the sphenoid It is bounded
Middle Cranial Fossa
Laterally :
the squamous parts of the temporal
bones, the greater wings of the
sphenoid,
and the parietal bones.
The floor of each lateral part of the
middle cranial fossa is formed by
the greater wing of the sphenoid and
the squamous and petrous parts of
the temporal bone.
Posteriorly by :the superior
borders of the petrous parts of
the temporal bones
Anteriorly by: the lesser wings
of the sphenoid
1-The body of the sphenoid :contains the
sphenoid air sinuses
2-The optic canal transmits
A- The optic nerve
B-The ophthalmic artery
3-The superior orbital fissure
is a slitlike opening between
the lesser and greater wings
of the sphenoid transmits:
The sphenoid bone
resembles a bat having a centrally placed body
with greater and lesser wings that are
outstretched on each side
Lacrimal
Frontal
Trochlear
Superior division of Oculomotor nerve
Nasociliary
Inferior division of oculomotor nerve
Abducent nerves
together with the superior ophthalmic vein.
Live
Free
To
See
No
Insult
At all
4-The foramen rotundum
situated behind the medial end of the superior
orbital fissure
Transmits the maxillary nerve.
5-The foramen ovale
lies posterolateral to the foramen rotundum
Transmits the mandibular nerve
the lesser petrosal nerve
6-The small foramen spinosum
lies posterolateral to the foramen
ovale The foramen transmits
The middle meningeal artery
7-Foramen lacerum
lies between the apex of the petrous part of the
temporal bone and the sphenoid bone
in life is filled by cartilage and fibrous
tissue, and only small blood vessels pass
through this tissue from the cranial cavity to
the neck.
8-The carotid canal
Transmits: The internal carotid artery
9- Meckl’s cave:
impression on the apex of the petrous part of
the temporal bone for the trigeminal ganglion
10-The median part of the middle cranial
fossa is formed by:
the body of the sphenoid bone
In front of it is
The sulcus chiasmatis
which is related to the optic chiasma
and leads laterally
To
THE OPTIC CANAL
On the superior aspect of the body is a
depression called
The sella turcicawhich CONTAIN
THE PITUITARY GLAND
The sella turcica is bounded posteriorly by
a square plate of bone called
THE DORSUM SELLAEThe superior angles of the dorsum sellae
have
two tuberclescalled
The posterior clinoid processes
which give attachment to the fixed
margin of
The tentorium cerebelli.
Posterior Cranial Fossa
Contains the parts of the hindbrain:
The cerebellum, Pons, and Medulla
oblongata
The roof is formed by:
a fold of dura
THE TENTORIUM CEREBELLI
which intervenes between the
cerebellum below And
the occipital lobes of the cerebral
hemispheres above
Is bounded by:
Anteriorly: the petrous part of the temporal bone
Posteriorly : the internal surface of the
squamous part of the occipital bone
The floor is formed by:Parts of the occipital bone
The mastoid part of the temporal bone
1-The internal acoustic meatus
pierces the posterior surface of the petrous part
of the temporal bone.
It transmits:
A- THE VESTIBULOCOCHLEAR NERVE
B- THE FACIAL NERVE.
3- Groove for the transverse sinus:
On each side of the internal occipital
protuberance
2-The internal occipital protuberance
attached to it the small falx cerebelli
4-the sigmoid sinus
4-the sigmoid
sinus
5-The foramen magnum
occupies the central area of the floor
Transmits
A- The medulla oblongata and its
surrounding meninges
B- The ascending spinal parts of the
accessory nerves
C-The two vertebral arteries
6-The hypoglossal canal
is situated above the anterolateral boundary
of the foramen magnum
Transmits the hypoglossal nerve
7-The jugular foramen
It transmits the following structures:
from before backward:
A-The inferior petrosal sinus
B-The 9th, 10th, and 11th cranial
nerves
C- The large sigmoid sinus
D-The inferior petrosal sinus
E-The sigmoid sinus turns down
through the foramen
to become the internal jugular
vein
Inferior View of the Skull
1-The hard palate whic is made of:
A-The palatal processes of the
maxillae (vertical)
B-The horizontal plates of the
palatine bones
2-Incisive fossa and foramen
3-The greater and lesser palatine
foramina
4-The choanae (posterior nasal
apertures).
5-The vomer
6-Medial and lateral pterygoid
plates
of the sphenoid bone
9-The spine of the sphenoid
LOCATED Posterolateral to
the foramen spinosum is
The greater wing of the sphenoid is
pierced by the large
7-foramen ovale
8-foramen spinosum
10-The mandibular fossa of the temporal bone
and the articular tubercle form the upper
articular surfaces for the temporomandibular
joint.
12-Tympanic plate of the
temporal bone
11-The styloid process of
the temporal bone
14-The opening of the
carotid canal
15- Foramen lacerum
13-the external
auditory meatus
16- The stylomastoid foramen
In the interval between the styloid and mastoid
processe
17-jugular foramen
18-Hypoglossal canal
Superior to the occipital condyle
for transmission of the
hypoglossal nerve
19-The basilar part of the
occipital bone
20-The occipital condyles
21-The external
occipital
protuberance.
22- The superior nuchal lines :posterior to the
foramen magnum in the midline