External Lateral View of the Skull

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Initial Viewing of the Skull
Illustrated Anatomy of the Head and Neck
Third Edition
Margaret J. Fehrenbach and Susan W. Herring
Elsevier, 2007
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NOTE

It is easier to study the skull by first looking
at its various views: the superior, anterior,
lateral, and inferior views.
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Superior View of the Skull
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When the skull is
viewed from above, four
cranial bones are
visible.
At the front of the skull
is the single frontal
bone.
At the sides are the
paired parietal bones.
At the back of the skull
is the single occipital
bone.
Figure 3-1
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SUTURES ON SUPERIOR VIEW
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The suture extending across
the skull, between the frontal
and parietal bones, is the
coronal suture.
A second suture, the sagittal
suture, extends from the
front to the back of the skull,
between the paired parietal
bones.
The third suture, located
between the single occipital
bone and the paired parietal
bones, is the lambdoidal
suture.
Figure 3-2
4
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Anterior View of the Skull
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When the skull is viewed
from the front, certain bones
of the skull (or portions of
these bones) are visible.
These bones include the
single frontal, ethmoid,
vomer, and sphenoid bones
and the mandible, and also
the paired lacrimal, nasal,
inferior nasal conchal,
zygomatic, and maxillary
bones.
Figure 3-3
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Facial Bones on Anterior View

The facial bones
visible on the anterior
view of the skull include
the lacrimal bone, nasal
bone, vomer, inferior
nasal concha,
zygomatic bone,
maxilla, and mandible.
Figure 3-4
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Orbit and Associated Structures
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The orbit contains and protects
the eyeballs.
The larger orbital walls are
composed of the orbital plates
of the frontal bone (roof or
superior wall), ethmoid bone
(greatest portion of medial wall),
and lacrimal bone (at the
anterior medial corner of the
orbit) and the orbital surfaces of
the maxilla (floor or inferior wall)
and zygomatic bone (anterior
portion of the lateral wall).
The orbital surface of the
greater wing of the sphenoid
bone is also included (the
posterior portion of the lateral
wall).
Figure 3-5
7
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Orbit and Associated Structures
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The orbital apex is
composed of the lesser wing
of the sphenoid bone
(forming the base) and the
palatine bone (a small
inferior portion).
The opening in the orbital
apex is the optic canal,
which lies between the two
roots of the lesser wing of
the sphenoid bone.
The second cranial or optic
nerve passes through the
optic canal to reach the
eyeball. The ophthalmic
artery also extends through
the canal to reach the eye.
Figure 3-6
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Orbit and Associated Structures
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Lateral to the optic canal is
the superior orbital fissure,
between the greater and
lesser wings of the sphenoid
bone. Like the optic canal,
the superior orbital fissure
connects the orbit with the
cranial cavity.
The third cranial or
oculomotor nerve, the fourth
cranial or trochlear nerve,
the sixth cranial or abducent
nerve, and the ophthalmic
nerve (from the fifth cranial
or trigeminal nerve) and vein
travel through this fissure.
Figure 3-7
9
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Orbit and Associated Structures
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The inferior orbital fissure
can be seen between the
greater wing of the sphenoid
bone and the maxilla.
The inferior orbital fissure
connects the orbit with the
infratemporal and
pterygopalatine fossae.
The infraorbital and
zygomatic nerves, branches
of the maxillary nerve, and
infraorbital artery enter the
orbit through this fissure.
The inferior ophthalmic vein
travels through this fissure to
join the pterygoid plexus of
veins.
Figure 3-7
10
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Nasal Cavity and Associated
Structures
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The nasal cavity can also
be viewed from the anterior
aspect.
The nasion, a midpoint
landmark, is located at the
junction of the frontal and
nasal bones.
The anterior opening of the
nasal cavity, the piriform
aperture, is large and
triangular.
The bridge of the nose is
formed from the paired nasal
bones. The lateral
boundaries of the nasal
cavity are formed by the
maxillae.
Figure 3-8
11
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Nasal Cavity and Associated
Structures
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Each lateral wall of the
nasal cavity has three
projecting structures
that extend inward from
the maxilla, which are
called the nasal
conchae.
Figure 3-8
12
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Nasal Cavity and Associated
Structures
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The vertical partition of the
nasal cavity, the nasal
septum, divides the nasal
cavity into two portions.
Anteriorly, the nasal septum
is formed by both the nasal
septal cartilage inferiorly and
the perpendicular plate of
the ethmoid bone superiorly.
The posterior portions of the
nasal septum are formed by
the vomer.
Figure 3-9
13
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External Lateral View of the Skull
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When viewed from the side,
the external skull shows both
cranial bones and facial
bones.
A division between the
cranial bones and facial
bones can be reinforced by
making an imaginary
diagonal line that passes
downward and backward
from the supraorbital ridge of
the frontal bone to the tip of
the mastoid process of the
temporal bone.
Figure 3-10
14
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External Lateral View of the Skull
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On the lateral external
surface of the skull are two
separate parallel ridges or
temporal lines, crossing
both the frontal and parietal
bones.
The superior ridge is the
superior temporal line.
The inferior ridge or inferior
temporal line is the superior
boundary of the temporal
fossa and where the
temporalis muscle attaches.
Figure 3-11
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Cranial Bones on
External Lateral View

From the lateral view,
the cranium is easily
seen, which includes
the cranial bones: the
occipital , frontal,
parietal, temporal,
sphenoid, and ethmoid
bones.
Figure 3-12
16
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Cranial Bones on
External Lateral View
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Also present on the lateral
view of the cranium are the
coronal suture, an
articulation between the
frontal and parietal bones,
and the lambdoidal suture,
an articulation between the
parietal and occipital bones.
Also present is the
squamosal suture, between
the temporal and parietal
bones.
Figure 3-12
17
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Fossae on
External Lateral View
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The temporal fossa is
formed by several
bones of the skull and
contains the body of the
temporalis muscle.
Inferior to the temporal
fossa is the
infratemporal fossa.
Deep to the
infratemporal fossa and
harder to see is the
pterygopalatine fossa.
Figure 3-13
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Zygomatic Arch and TMJ on
External Lateral View
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The zygomatic arch is
formed by the union of the
broad temporal process of
the zygomatic bone and the
slender zygomatic process
of the temporal bone.
The suture between these
two bones is the
temporozygomatic suture.
The zygomatic arch serves
as the origin for the masseter
muscle.
Figure 3-14
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Zygomatic Arch and TMJ on
External Lateral View
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The
temporomandibular
joint is a movable
articulation between the
temporal bone and the
mandible.
Figure 3-14
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Inferior View of the
External Surface of the Skull
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Most of the structures of the
inferior aspect of the skull
surface are more easily
viewed on the skull model
if the mandible is
temporarily removed.
The maxillary, zygomatic,
vomer, temporal, sphenoid,
occipital, and palatine bones
are visible on this inferior
view of the skull’s external
surface.
Figure 3-15
21
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Hard Palate and
Associated Structures
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At the anterior portion of
the skull’s inferior
aspect is the hard
palate, bordered by the
alveolar process of the
maxilla with its maxillary
teeth.
The hard palate is
formed by the two
palatine processes of
the maxillae and the
two horizontal plates of
the palatine bones.
Figure 3-16
22
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Hard Palate and
Associated Structures
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Two sutures are present on
the hard palate. One suture
is the median palatine
suture, a midline articulation
between the two palatine
processes of the maxillae
anteriorly and the two
horizontal plates of the
palatine bones posteriorly.
The other suture is the
transverse palatine suture,
an articulation between the
two palatine processes of
the maxillae and the two
horizontal plates of the
palatine bones.
Figure 3-16
23
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Hard Palate and
Associated Structures
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The hard palate forms the floor
of the nasal cavity, as well as
the roof of the mouth. The
posterior edge of the hard
palate forms the inferior border
of the posterior nasal
apertures or choanae.
The superior border of each
aperture is formed by the vomer
and the sphenoid bone.
The posterior edge of the vomer
forms the medial border of the
posterior nasal apertures. The
posterior nasal apertures are
the posterior openings of the
nasal cavity.
Figure 3-16
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Hard Palate and
Associated Structures
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Near the superior
border of each posterior
nasal aperture is the
pterygoid canal.
The pterygoid canal
extends to open into the
pterygopalatine fossa
and carries the
pterygoid nerve and
blood vessels.
Figure 3-16
25
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Middle Portion of the
External Skull Surface
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The lateral borders of
the posterior nasal
apertures are formed on
each side by the
pterygoid process of
the sphenoid bone.
Each pterygoid process
consists of a medial
pterygoid plate and a
lateral pterygoid plate.
Figure 3-17
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Middle Portion of the
External Skull Surface
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The depression
between the medial and
lateral plates is called
the pterygoid fossa.
At the inferior portion of
the medial plate of the
pterygoid process is the
hamulus.
Figure 3-17
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Foramina of the
External Skull Surface
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The larger anterior oval
opening on the
sphenoid bone is the
foramen ovale, through
which the mandibular
division of the fifth
cranial or trigeminal
nerve.
Figure 3-18
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Foramina of the
External Skull Surface
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The smaller and more
posterior opening is the
foramen spinosum,
which carries the middle
meningeal artery into
the cranial cavity.
The foramen spinosum
receives its name from
the nearby spine of the
sphenoid bone, which is
at the posterior
extremity of the
sphenoid bone.
Figure 3-18
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Foramina of the
External Skull Surface
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Also on the external surface
of the skull is the large
foramen lacerum.
Posterolateral to the foramen
lacerum is an opening in the
petrous portion of the
temporal bone, the carotid
canal.
The carotid canal carries the
internal carotid artery and
sympathetic carotid plexus.
Figure 3-18
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Foramina of the
External Skull Surface
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A bony projection, the
styloid process, is
visible lateral and
posterior to the carotid
canal.
Immediately posterior to
the styloid process is
the stylomastoid
foramen, an opening
through which the
seventh cranial or facial
nerve exits from the
skull to the face.
Figure 3-18
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Foramina of the
External Skull Surface
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The jugular foramen, just
medial to the styloid process,
is more easily seen if the
skull model is tilted to one
side.
The jugular foramen is the
opening through which pass
the internal jugular vein and
three cranial nerves: the
ninth cranial (glossopharyngeal) nerve, tenth
cranial (vagus) nerve, and
eleventh cranial (accessory)
nerve.
Figure 3-18
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Foramina of the
External Skull Surface
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The largest opening on
the inferior view is the
foramen magnum of
the occipital bone,
through which pass the
spinal cord, vertebral
arteries, and eleventh
cranial or accessory
nerve.
Figure 3-18
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Superior View of the
Internal Surface of the Skull
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The internal surface of
the skull is viewed by
carefully removing the
top half of the skull
model.
The frontal, ethmoid,
sphenoid, temporal,
occipital, and parietal
bones are visible from
this view of the internal
surface of the skull.
Superior orbital fissure
Foramen lacerum
Figure 3-19
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Foramina of the
Internal Skull Surface
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Also present are the inside
openings of the optic canal,
superior orbital fissure,
foramen ovale, foramen
spinosum, carotid canal,
jugular foramen, and
foramen magnum.
The perforated cribriform
plate, with foramina for the
first cranial or olafactory
nerve, and the foramen
rotundum, for the maxillary
division of the fifth cranial or
trigeminal nerve, are also
seen from this view.
Superior orbital fissure
Foramen lacerum
Figure 3-19
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Foramina of the
Internal Skull Surface
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Also present are the
hypoglossal canal, for
the twelfth cranial or
hypoglossal nerve, and
the internal acoustic
meatus, for the seventh
cranial or facial nerve
and the eighth cranial or
vestibulocochlear
nerve.
Superior orbital fissure
Foramen lacerum
Figure 3-19
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Fig 3-22
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Fig 3-23
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Fig 3-26
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Fig 3-31
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Fig 3-32
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Fig 3-44
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Fig 3-48
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Fig 3-51
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Fig 3-52
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Fig 3-60
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