2. Intended learning outcomes :
By the end of this presentation students
will be able to:
o Locate and identify bones that comprise the skull.
o Differentiate between Neur-ocranium and facial skeleton
o Discuss the Normas of the skull .
o Identify the major features of bones that form the skull.
o List the external foramina of the skull.
o Describe the bones forming each part of the cranial fossa.
o List the foramens , structures that pass through found in the
skull.
3. Introduction
The skeleton of head and neck consists of skull, cervical
vertebrae, and hyoid bone.
The prominences and depressions on the bony surface are
landmarks for attachments of the muscles, tendons, and
ligaments. The openings in the bone are also landmarks where
various nerves and blood vessels enter or exit.
4. The Skull
The bony skeleton of the head is termed skull. It
consists of 22 bones excluding ear ossicles.
The human skull is a bony structure, skeleton
part , which supports the structures of the face
and forms a cavity for the brain.
Irregular bone
5. Cont..
Except mandible (bone of lower jaw), all the bones of skull,
joined together by sutures, those are immobile and form the
cranium. However, the two terms skull and cranium are generally
used synonymously.
6. Parts of the skull
The skull is subdivided into two parts:
1.An upper dome-shaped part which covers the cranial cavity
containing brain is called cranial vault/calvaria/ brain box.
It is attached to the skull base below. The cranial vault along with
skull base is called cranial skeleton/ cranium.
2. A lower anterior part is called facial skeleton, which includes
mandible.
7. Cont..
• The cranium (cranial skeleton) is a strong and rigid container
for the brain, while the facial skeleton is a rather fragile and
light basis for face. The facial skeleton lies below the anterior
part of the cranium in human beings.
• Many anatomists use alternative terms, neurocranium for the
cranial skeleton and viscerocranium for the facial skeleton.
9. BONES OF THE SKUL
The skull is made up of 22 bones, excluding ear ossicles.
Cranial skeleton, consisting of 8 bones, out of which two are
paired and four unpaired.
Paired bones are :parietal and temporal
Unpaired bones are :Frontal ,Occipital , Sphenoid and Ethmoid.
Facial skeleton, consisting of 14 bones, out of which six are
paired and two unpaired:
Paired bones :Maxillary, zygomatic,nasal, lacrimal, palatine,and
Inferior nasal concha
Unpaired bones :Mandible and Vomer
10. Cont.
The skull also contains the sinus cavities (Para-nasal sinuses),
which are air-filled cavities lined with respiratory epithelium,
which also lines the large airways.
25. Neurocranium (cranial vault)
It is upper posterior part of skull which enclose the brain, the
cranial meninges and It also contains proximal parts of the
cranial nerves and the vasculature of the brain.
The neurocranium has a calvaria (skullcap), and a floor or cranial
base (basicranium).
26. Bones form the neurocranium
Unpaired bones:
Paired bones:
Frontal
Ethmoid
Sphenoid
Occipital
Temporal
Parietal
28. The viscerocranium (facial skeleton)
It is anterior part of skull which consists of bones surrounding the:
mouth (upper and lower jaws).
nose/nasal cavity.
most of the orbits (eye sockets or orbital cavities).
29. Bones form the viscerocranium
Paired bones: Unpaired bones:
Zygomatic
Nasal
Lacrimal
Maxilla
Palatine
Inferior nasal concha
Vomer
Mandible
32. The external features of the skull are studied from five
different aspects
Norma verticals : superior aspect.
Norma frontal's : anterior aspect.
Norma lateralis : lateral aspect.
Norma occipitalis: posterior aspect.
Norma basalis externa : inferior aspect (skull base)
from outside.
Norma basalis internal : inferior aspect (skull base)
from inside.
33. When the skull is viewed from above, it appears
oval, being wider posteriorly than anteriorly.
It represents flowing different features: bones,
sutures and other special features.
34. Bones forming it; four
bone:
Frontal
Occipital
2 parietal on each side
Sutures between the
bones:
coronal suture
Sagittal suture
Lambdoid suture
35.
36. Special features:
1.Bregema:meeting point of the sagittal and coronal sutures
2.Lambda:meeting of sagital and lamboid sutures,
3.Vertex:It is the highest point on the skull. It lies on the sagittal
suture near its middle and is situated a few centimeters behind
the bregma.
4.Parital foremen: emissary vein b/w superior sagittal sinus and
scalp vein
37.
38. Bregma
The point meet between
coronal and sagittal
suture . at birth it is filled
with fibrous membrane
called Anterior
fontanelle, Which ossify
at 18 month.
Lambda:
The point of meeting between sagittal
and lambdiod , at birth it occupied by
membrane called posterior
fontanelle,
which ossify at 6-12month
40. Norma Frontals
In frontal view, the skull appears oval, being wider above
and narrower below. The anterior aspect of the skull
presents the following features.
Frontal region formed by frontal bone.
Orbital openings.
Prominences of the cheek formed by zygomatic bones.
Bony external nose and anterior nasal aperture.
Upper and lower jaws bearing teeth
41. Bones forming it:
1.Frontal
2.2Nasal
3.2 Zygomatic
4.2Maxillary
5.Mandible
Sutures between the
bones:
1.Mytopic
2.Frontomaxillary
3.Frontonasal
4.Intermaxillary
5.Zygomatomaxillary
43. The frontal region or the forehead is formed by the
squamous part of the frontal bone. Below on each side of
median plane, it articulates with the nasal bones. Frontal
region presents the following features: superciliary arches,
glabella, and frontal eminences.
The upper part :
Forehead(frontal bone).
Middle part:
Containing three cavities 2orbital cavities and nasal cavity.
Lower part:
formed by upper and lower jaw.
44. Orbital opening
These are the openings of two orbital cavities on the face. Each
opening is present above and lateral to the anterior nasal
aperture. It is quadrangular in shape and presents four margins.
1-The supraorbital margin is formed entirely by the frontal bone.
there is a notch called supraorbital notch (or foramen in some
skulls), through which passes the supraorbital nerve and vessels.
2-The lateral orbital margin is formed by the frontal process of
zygomatic bone and zygomatic process of frontal bone.
45. 3.The infraorbital margin is formed by the zygomatic bone
laterally and the maxilla medially.
Below this margin the maxilla presents an opening called
infraorbital foramen through which passes the infraorbital
nerve and vessels.
4.The medial orbital margin is ill-defined as compared to
other margins. It is formed by the frontal bone above and the
anterior lacrimal crest of the maxilla below.
46. Special features:
Frontal eminence: Centre of ossification
Superciliary arch: above the orbit
Glabella:elevation b/w the 2superciliary arches
Nasion :depression at the fronto-nasal suture
Orbital openings
Anterior nasal aperture
53. When the skull is viewed from behind, it appears convex
upwards and on sides but flattened below. It presents the
following features:
Bones:
The bones seen in this view are posterior portions of parietal
bones, the upper part of occipital bone, and mastoid parts of
temporal bones.
54. They are located as follows:
1.Parietal bones, superiorly one on each side.
2. Occipital bone (squamous part), inferiorly.
3. Mastoid part of temporal bone, inferolaterally on each
side
55. Sutures between bones:
The sutures which unite these bones are as follows:
1.Lambdoid suture, between occipital and two parietal
bones.
2.Occipitomastoid suture, between occipital and mastoid
part of temporal bone.
3.Parietomastoid suture, between parietal and mastoid part
of temporal bone.
56.
57. Special features:
External occipital protuberance
External occipital crest
Nuchal line (superior , inferior and highest).
Mastoid emissary foramen
Aster-ion: site of meeting of 3 bones and
posteriolateral fontanel and ossifies at 3months.
Mastoid foramen: transmits emissary vein and
meningeal branch of occipital artery.
60. When skull is viewed from its lateral aspect it presents the
following features:
Bones:
The bones seen on the lateral aspect of skull are frontal, parietal,
occipital, temporal, sphenoid, zygomatic, mandible, maxilla, and
nasal.
Sutures:
Coronal suture, and lambdoid suture
Parietosquamosal suture, between parietal and squamous part of
temporal bones.
63. Temporal line(superior and
inferior)
Styloid and mastoid processes
Zygomatic arch
External auditory meatus
Supra mastoid crest
Suprameatal
Pterygomaxillary fissure
Fossae( temporal, infra
temporal and
pterygopalatine ).
64. Asteorion: meeting site of three bone and posterolateral
fontanel
Pterion: meeting point of four bones and site of
anterolateral fontanel which ossifies at 3 months .
Clinical importance: it over lies anterior branch of middle
meningeal artery which can leads extra Dural
hemorrhage during injury of the pterion.
71. The Norma basalis (undersurface of the skull) is
divided into three regions or parts:
anterior, middle, and posterior divided by two
imaginary transverse lines.
1.Anterior transverse line, which passes along
the posterior-free margin of the hard palate.
2. Posterior transverse line, which passes along
the anterior margin of the foramen magnum.
72. * Inferior view of the skull
Anterior part
n
Middle part
Posterior part
73. It is formed by hard palate and alveolar processes of the
maxillae.
Features in the anterior part of norma basalis are as follow:
1-Alveolar arch: The alveolar processes of two maxillae forms
a U-shaped ridge of bone called alveolar arch, which bears the
sockets for the roots of upper teeth.
2-Hard palate: It is formed by two pairs of bony processes:
(a) palatine processes of maxillae in front( anterior2/3)
(b) horizontal plates of palatine bones behind (posterior 1/3).
The hard palate presents intermaxillary, interpalatine(midline),
and palatomaxillary sutures b/w maxilary &palatin bone.
74. It extends from posterior margin of the hard palate to
an imaginary transverse line that crosses the anterior
margin of the foramen magnum.
Midline bones:
vomer which is posterior part of nasal septum
Body of sphenoid bone
Basilar part of occipital bone
Occipitosphenoid suture
75. It presents:
Median and lateral pterygoid plates of sphenoid
G/wing of sphenoid bone contains:
Foramin ovale transmits(male) mandibular nerve ,accessory
meningeal artery, lesser petrossal nerve, and emissary vein.
Foramen spinosum transmits middle meningeal artery and
nervous spinosum, Groove for auditory tube , foramen
lacerum, and carotid canal,styloid process,mandibular joint
fossa and jugular foramen
76. It is behind the imaginary transverse line passing
along the anterior margin of the foramen
magnum.it is formed by occipital bone and
mastoid process.
Occipital bone is divided into3parts by foreman
magnum:
Basilar part: front of the foreman
Squamous part: behind the foramen
Condylar part:2occipital condyles
77. Features in the posterior part are as follows:
Foramen magnum , External occipital crest, Stylomastoid
foramen,External occipital protuberance, Hypoglossal canal,
Jugular foramen
78. m
p
s
t
v
o
incisive fossa
palatine process
of maxilla
horizontal process
of palatine bone
choana
greater wing
pterygoid
process
body of sphenoid
foramen lacerum
foramen ovale
foramen spinosum
mandibular
fossa
styloid
process
external
auditory
meatus
mastoid
process
foramen magnum
inf. nuchal line
sup. nuchal line
carotid canal
