this is presentation of osteology of skull .

1. Osteology of skull
Dr. Aroosa Tariq
MSNMPT, DPT(GOLD MEDALIST)
Lecturer PT
Faculty of Rehabilitation and Allied Health Science
Riphah International University

2.  The skull is divided into two
parts:
1. Neurocranium- which forms a
protective case or “vault”
around the brain
2. Viscerocranium- which forms
the anterior part of the skull
including the orbits, nasal
cavities and upper/lower jaw
bones
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The Skull
Neurocranium
Viscerocranium

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The Skull
Frontal coronal suture
Parietal
Sphenoid
Temporal
Occipital

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Mandible
maxilla
Nasal
Inferior
Nasal
conchae
Vomer
The Skull
Lacrimal
Zygomatic
Inferior Nasal
Conchae
Vomer
Mandible
Maxilla
Nasal

7.  Squamous (flat) portion forms the
skeleton of the forehead
 Fontal bone forms the roof of the
orbit
 Nasion is an area where the frontal
bone intersects with the nasal
bones
 Glabella- smooth, slightly
depressed area located just
superior to the nasion
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Frontal
bone
Nasion Glabella
Frontal Bone
Squamous
portion
Orbital
portion
Nasion
Glabella
Frontal
Bone

8.  Supraorbital margin-
marks the boundary
between the squamous
and orbital portions
 Supraorbital notch or
foramen is for the passage
of the supraorbital nerve
and vessels
 A prominent ridge just
superior to the
supraorbital margin is the
superciliary arch (more
pronounced in males)
 Zygomatic process of the
frontal bone articulates
with the zygomatic bone
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Supraorbital
margin
Supraorbital
notch
Superciliary
arch
Zygomatic
process
Frontal Bone

9.  Cheek bones
 Forms a portion of the lateral wall of
the orbit
 Frontal Process of the zygomatic bone
articulates with the frontal bone
 Temporal process of the zygomatic
bone articulates with the temporal
bone
 Zygomaticofacial foramen- small
foramen for passage of the
zygomaticofacial nerve
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Frontal
process
Temporal
process
Zygomaticofacial
foramen
Zygomatic Bones

10.  Forms the upper jaw
 Alveolar processes of the maxillae
includes the sockets and supporting
bone for the maxillary teeth
 Maxillae form the floor of the orbit
 Large infraorbital foramen for
passage of the infraorbital nerve &
vessels
 Surrounds most of the pear-shaped
piriform aperture
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Piriform
aperture
Alveolar
process
Infraorbital
foramen
Maxillae
Maxilla

11.  Frontal processes of the maxillae
articulates with the frontal bone
 Zygomatic processes of the
maxillae articulates with the
zygomatic bones
 Anterior nasal spine- sharp
prominence at inferior aspect of
the piriform aperture
 Intermaxillary suture- site where
the two maxilla are united in the
median plane
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Maxillae
frontal
process
Anterior
nasal
spine
Intermaxillary
suture
Zygomatic
process

12.  Seen within the piriform aperture
are the scrolled middle nasal
conchae (part of the ethmoid
bone) & the inferior nasal
conchae
 Vomer bone along with the
perpendicular plate of the
ethmoid bone which together
form the bony nasal septum can
also be identified with the piriform
aperture
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Vomer
Middle &
Inferior
concha
Perpendicular
plate

13.  U-shaped bone with alveolar process
that houses the mandibular teeth
 Mental foramen- located inferior to
2nd premolar for passage of the
mental nerve and vessels
 Mental protuberance- a triangular
elevation of bone that forms the
prominence of the chin
 Mental tubercle- located just lateral
to the protuberance
 Body is the horizontal portion
 Ramus is the vertical portion
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Ramus
Body
Mental
foramen
Mental protuberance
Alveolar
process
Mandible

14. Osteology
Lateral Aspect of the Skull

15. 1. Parietal bone
2. Frontal bone
3. Occipital bone
4. Temporal bone
5. Sphenoid bone
6. Mandible
7. Zygomatic bone
8. Maxillae
9. Lacrimal bone
10. Nasal bone
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Lateral Aspect of the Skull
1.
4.
2.
3.
6.
9.
8.
10.
5.
7.

16.  Paired bones that form the lateral
& superior cranium
 Temporal Lines- mark the
attachment site of the temporalis
muscle & fascia
 Articulates with frontal bone via
coronal suture
 Articulates with occipital bone via
lambdoid suture
 Pterion-site where 4 cranial bones
articulate-important clinical
implications
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Parietal
Coronal suture
Lambdoid
suture
Temporal
lines
Parietal Bones
pterion

17.  Paired bones that form the
inferior lateral aspect of skull
 Temporal bone is described as
having a flat squamous portion
and a mastoid process (site of
attachment of several muscles)
 Zygomatic arch extends
anteriorly to articulate with the
zygomatic bone
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Mastoid
process
Zygomatic arch
Temporal Bones
Squamous

18.  External acoustic meatus (ear
canal) and the pointed styloid
process are considered to be
located the tympanic portion of
the temporal bone
 Styloid process serves as the
attachment site for several
muscles and the stylohyoid
ligament
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External
acoustic
meatus
Styloid process
Temporal Bones

19.  Mandible and a portion of the
zygomatic arch removed in this
view
 Located on the inferior aspect of
the arch is a small bony
protrusion- articular tubercle that
is important in the mechanics of
the TMJ
 Mandibular fossa- deep recess
that accepts the condyle of the
mandible-also important region of
the TMJ
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Articular
tubercle
Mandibular
fossa
Temporal Bones

20.  Forms major portion of the
cheek
 Temporal process that
articulates with the zygomatic
arch
 Frontal process that articulates
with the frontal bone
 Zygomaticofacial foramen –
small foramen generally visible
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Zygomatic bone
Temporal process
Frontal process
Zygomatic arch
Zygomaticofacial
foramen

21.  Forms the posterior aspect of the
skull
 Articulates with the parietal bone
via the lambdoid suture
 Prominent palpable elevation
located posteriorly is the external
occipital protuberance
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Lambdoid
suture
External
Occipital
protuberance
Occipital Bone

22.  Irregular shaped bone that forms a
portion of the orbit, lateral aspect
of skull and a portion of the
cranial base
 Sphenoid can be divided into 4
parts:
1. Greater wing
2. Lesser wing
3. Pterygoid processes
4. Body
 Some portions of the sphenoid can
only be seen inside the cranial
cavity
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Sphenoid Bone
Sphenoid Bone

23.  Portion of zygomatic arch and mandible
removed in this view
 Greater wing articulates with the
temporal, parietal & frontal bones at the
pterion
 Pterygoid processes are two thin plates
of bone that serve as attachment sites
for muscles
 Pterygoid hamulus-small hook of bone
extending from the medial pterygoid
plate- tensor veli palatini tendon courses
around this
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Greater wing
Pterygoid
process
Pterygoid
hamulus
4 portions of Sphenoid Bone

24.  Portion of zygomatic arch and mandible
removed in this view
 Posterior aspect of the maxillae is
referred to as the tuberosity of
maxillae
 Small alveolar foramina for the
posterior superior alveolar nerves &
vessels
 Pterygomaxillary fissure-tear-drop
shaped fissure between the sphenoid
and tuberosity of the maxillae
 Pterygopalatine fossa is a small but
important space located medial to the
fissure- Pterygopalatine ganglia-
the maxillary nerve gives of numerous
branches including the infraorbital,
zygomatic, nasopalatine, superior
alveolar, pharyngeal and the greater
and lesser palatine nerves. 3/18/2
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Tuberosity of
maxilla
Alveolar
foramen
Pterygomaxillary
Fissure
Maxillae

25. Lateral Aspect of Skull
 Nasal bone can also identified as
it articulates with the frontal bone
and the maxillae
 Lacrimal bone- which houses the
lacrimal sac can be identified
within the orbit
 Prominent anterior nasal spine at
the inferior aspect of the piriform
aperture
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Nasal
spine
Nasal
bone
Lacrimal bone

26. Mandible
 Condylar process is located at the
superior part of the ramus and
involved in the articulation of the
mandible with the temporal bone
(TMJ)
 Coronoid process is located just
anterior and serves as the
attachment site for the temporalis
muscle
 Angle of mandible is between the
ramus and body
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Angle
Condylar
process
Coronoid
process

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Ramus
Body
Alveolar Part (crest)
Condylar Process
Coronoid process
Mental foramen
Lingula
Mandibular
foramen
Mylohyoid line
Infant
Mandible

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Body
Ramus
Condylar process
Mandibular notch
Bone loss due to tooth loss
Mental spines
Mandible

29. Calvaria
 Emissary foramen- small, inconsistent
(not always present) foramina for
passage of emissary veins
 Bregma- is the landmark formed by
the intersection of the sagittal &
coronal sutures
 Lambda-is the landmark formed by
the intersection of the sagittal &
lambdoid sutures
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Coronal
suture
Sagittal
suture
Emissary
foramen
Lambdoid
suture
Bregma
Lambda

30. Calvaria
 Inferior aspect of the skull cap
presents several features:
 Vascular grooves for branches of
the middle meningeal artery
 Granular Foveolae- pits formed by
arachnoid granulations (site of CSF
transfer)
 Groove for the superior sagittal
sinus-large venous channel within
the dura mater
 Diploe- cancellous bone containing
red marrow
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Groove for superior
sagittal sinus
Grooves for
middle
meningeal
artery
Diploe
Granular
foveolae

31. Infant Skull
Superior & Lateral Aspects

32. Infant Skull
 Bones forming the calvaria & some
parts of the cranial base develop by
intramembranous ossification
 Whereas-most parts of the cranial
base develop by endochondral
ossification
 Bones in the infant skull are separated
by areas of fibrous tissue membranes-
the fontanelles:
 Anterior
 Posterior
 Mastoid
 sphenoidal
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Anterior
Posterior
Sphenoidal
Mastoid

33. Infant Calvaria
 Anterior Fontanelle (soft spot) is
the future site of the bregma
 By about 18-24 months- the
surrounding bones fuse together
and is no longer palpable
 Posterior Fontanelle is triangular
and marks the future site of the
lambda
 Fusion of surrounding bones occurs
by about 12 months
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Anterior
fontanelle
Posterior
fontanelle
Fontanelles- membranous gaps (soft spots) in skull that permit growth

34. Infant Skull
 Mastoid & sphenoidal fontanelles
fuse early in infancy
 Palpation of fontanelles during
infancy enables physicals to
determine:
1. Growth progress of the frontal &
parietal bones
2. Degree of hydration of the infant (a
depressed fontanelle indicates
dehydration)
3. Level of intracranial pressure-bulging
fontanelle indicates increased
pressure on the brain
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Anterior
Posterior
Sphenoidal
Mastoid

35. Osteology
External Aspect of the Cranial
Base

36. Cranial Base
 Inferior aspect of the skull presents six
different bones:
1. Palatine processes of the maxillae
2. Palatine bone
3. Sphenoid bone
4. Vomer
5. Temporal
6. Occipital bone
 Numerous foramina can also be identified
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1
2
3
4
5
6

37. Cranial Base- Palate
 Hard palate is formed by the
palatine processes of the
maxillae and the horizontal plates
of the palatine bone
 Small prominence projecting
posteriorly form the hard palate in
the median plane is the posterior
nasal spine
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Horizontal
plate of the
Palatine bone
Palatine
processes
Posterior
nasal
spine

38. Cranial Base- Palate
 Posterior to the central incisors is
a small depression-incisive fossa
with a pair of canals- incisive
canals for the passage of the
nasopalatine nerves & greater
palatine artery
 Posterolaterally are the greater &
lesser palatine foramen for
passage of the nerves & vessels of
the same name
 Palatine Groove
Lateral aspect of palatine bone on
hard palate ;greater palatine artery
 Palatine crust
Posterior aspect arche of
palatinebone
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Greater and
Lesser
Palatine
foramina
Incisive
canals

39. Cranial Base-Vomer
 Vomer-thin, flat unpaired bone in
the midline that forms a major
portion of the bony nasal septum
 On either side of the vomer are
two large openings- choanae
(posterior nasal apertures)
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Choanae
Vomer

40. Cranial Base- Sphenoid
 Three parts of the sphenoid
bone can be appreciated on the
inferior aspect of skull:
1. Greater wing
2. Medial pterygoid plate
3. Lateral pterygoid plate
 Pterygoid fossa is between the
two pterygoid plates
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Greater
wing
Lateral
pterygoid
plate
Medial
pterygoid
plate

41. Cranial Base- Sphenoid
 Foramen ovale for passage of
the mandibular division (V3) of
the trigeminal nerve
 Foramen Spinosum- for passage
of the middle meningeal artery
 Groove for the
pharyngotympanic (auditory)
tube lies medial to Spinosum
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Foramen
ovale
Foramen
spinosum
Auditory
Tube-groove

42. Cranial Base- Temporal
 Mastoid process- prominence
located posteriorly on the
temporal bone
 Mastoid serves as the attachment
site for the SCM and posterior
belly of the digastric muscles
 External acoustic meatus (EAM) is
located just anterior to the
mastoid
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EAM
Mastoid
process

43. Cranial Base- Temporal
 Styloid process- thin bony process
extending inferior & anteriorly
 Styloid serves as attachment site
for numerous muscles & ligaments
 Mandibular fossa- articular
surface that accepts the condyle
of the mandible forming the TMJ
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Mandibular
fossa
Styloid
process

44. Cranial Base- Temporal
 Two important foramen can be
identified on the inferior aspect of
the temporal bone:
 Stylomastoid foramen- located
between the mastoid & styloid
processes is a small foramen for
the passage of the facial nerve (CN
VII)
 Carotid canal- passage for the
internal carotid artery into the
cranial cavity
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Carotid canal
Stylomastoid
foramen

45. Cranial Base- Occipital
 Occipital bone forms the
posterior and inferior aspects of
the skull
 Foramen Magnum- a large
foramen for passage of the
spinal cord
 Foramen magnum divides the
occipital bone into 3 parts:
1. Basilar Region
2. Condylar Region
3. Squamous Region
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1
2
3
Foramen
magnum

46. Cranial Base- Occipital
 Basilar portion presents a small
tubercle- pharyngeal tubercle
for attachment of the
pharyngeal constrictors
 Foramen lacerum (jagged-
shaped) is located lust lateral to
the basilar portion
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Pharyngeal
tubercle
Foramen
lacerum

47. Cranial Base- Occipital
 Condylar portion presents the
occipital condyles that articulate
with the atlas
 Jugular foramen- large foramen
between the occipital & temporal
bones for passage of cranial nerves:
IX, X, XI and the internal jugular
vein
 Hypoglossal canal for passage of the
hypoglossal nerve (CN XII)
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Jugular
foramen
Occipital
condyle
Hypoglossal
canal

48. Cranial Base- Occipital
 Squamous portion presents
the palpable external
occipital protuberance
 Superior & inferior nuchal
lines project laterally and
are sites for muscular
attachments
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External
occipital
protuberance
Superior &
inferior
nuchal lines

49. Osteology
Internal Aspect of the Cranial
Base

50. Cranial Base
 Internal aspect of the cranial
base is divided into three major
regions or fossae:
1. Anterior cranial fossa
2. Middle cranial fossa
3. Posterior cranial fossa
 These three fossae lie at
different levels and form the
bowl-shaped floor of the cranial
cavity
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Anterior cranial fossa
Middle cranial fossa
Posterior cranial fossa

51. Anterior Cranial Fossa
 Frontal lobes of the brain
occupies the anterior cranial
fossa
 Fossa is formed by the:
1. Orbital portion of the frontal
bone
2. Ethmoid bone in the middle
3. Lesser wing of the sphenoid
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Ethmoid
Orbital portion of
the frontal bone
Lesser wing of
the sphenoid

52. Anterior Cranial Fossa
 Frontal crest- a median bony
extension from the frontal bone
 Foramen cecum is located at the
base of the crest and is a small
foramen for passage a vessels
during development
 Crista galli- ridge of bone
projecting superiorly from the
ethmoid bone and serves as the
attachment for the cerebral falx
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Crista
galli
Frontal crest
Foramen cecum

53. Anterior Cranial Fossa
 On either side of the crista
galli is a “sievelike” Cribriform
plate for passage of the
olfactory axons into the cranial
cavity
 Optic canal for passage of the
optic nerve (CN II) and the
ophthalmic artery
can be appreciated within the
lesser wing of the sphenoid
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Cribriform plate
Optic canal

54. Middle Cranial Fossa
 Temporal lobes of the brain
occupy the middle cranial fossa
 Fossa is formed by the:
1. Greater wing of the sphenoid
2. Squamous portion of the
temporal bone
3. Petrous portion of the temporal
bone
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Greater wing
of sphenoid
Squamous
portion temporal
bone
Petrous portion
temporal bone

55. Middle Cranial Fossa
 Sella turcica- the saddle-like bony
formation located on the superior
aspect of the body of the sphenoid
 Sella turcica is surrounded by
anterior & posterior clinoid
processes
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Sella
turcica
Anterior and
Posterior clinoids

56. Middle Cranial Fossa
 Sella turcica is composed of
three parts:
1. Hypophyseal fossa (pituitary
fossa)
2. Tuberculum sellae (saddle horn)
3. Dorsum Sellae (back of the
saddle)
 Sella turcica- essentially houses
and guards the pituitary gland
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Hypophyseal fossa
Tuberculum sellae
Dorsum sellae

57. Middle Cranial Fossa
 Middle cranial fossa presents
five important foramina:
1. Superior orbital fissure for
passage of CN’s III, IV, V1 & VI
& ophthalmic veins
2. Foramen rotundum which
transmits the maxillary nerve
(V2)
3. Foramen ovale- which
transmits the mandibular
nerve (V3)
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Superior orbital fissure
Foramen rotundum
Foramen ovale

58. Middle Cranial Fossa
4. Foramen spinosum which
transmits the middle meningeal
artery
5. Foramen lacerum- nothing is
transmitted vertically thru this
foramen although the internal
carotid artery and some nerves
pass across the foramen
horizontally
 Grooves for the greater & lesser
petrosal nerves are located along
the anterior slope of the petrous
portion of the temporal bone
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Foramen spinosum
Foramen
lacerum
Petrosal grooves

59. Middle Cranial Fossa
 Petrous portion of the temporal
bone houses the middle and
inner ear cavities
 Arcuate eminence- marks the
roof of the anterior semicircular
canal of the inner ear cavity
 Trigeminal impression is located
just anteromedial the eminence-
which marks the location of the
sensory ganglion of the
trigeminal nerve
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Arcuate eminence
Trigeminal impression

60. Posterior Cranial Fossa
 The largest & deepest of the three
fossae
 Cerebellum, pons and medulla
occupy the posterior fossa
 Formed mainly by the occipital
bone and the petrous & mastoid
portions of the temporal bone
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Occipital
bone Temporal bone
Petrous portion

61. Posterior Cranial Fossa
 Clivus marks the anterior portion
of the occipital bone
 Foramen magnum- large
foramen that marks the
transition from the medulla to
the spinal cord
 Posterior to the foramen
magnum is the internal occipital
crest and internal occipital
protuberance
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clivus
Occipital crest
Internal occipital
protuberance

62. Posterior Cranial Fossa
 Broad grooves show the horizontal
course of the transverse and S-
shaped sigmoid sinuses (both dural
venous sinuses)
 Sigmoid sinus empties into the large
jugular foramen which also transmits
several cranial nerves:
1. Glossopharyngeal (CN IX)
2. Vagus (CN X)
3. Accessory (CN XI)
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Transverse
Sinus groove
Groove for the
Sigmoid sinus
Jugular
foramen

63. Posterior Cranial Fossa
 Internal acoustic meatus is located
just anterosuperior to the jugular
foramen
 Internal acoustic meatus transmits
the facial nerve (CN VII) and
vestibulochochlear nerve (CN VIII)
along with the labyrinthine artery
 Hypoglossal canal for the hypoglossal
nerve (CN XII) lies superior to the
margin of the foramen magnum
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Hypoglossal
canal
Internal
acoustic
meatus

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Cribrifrom plate-CN I
Optic Canal CN II
Superior Orbital Fissure
CN III, IV, V1 & VI
Hypoglossal Canal
CN XII
Jugular Foramen- CN IX, X and XI
Internal Acoustic Meatus-
CN VII & VIII
Foramen Rotundum- CN V2
Foramen Ovale-CN V3

65. Osteology of the Orbit
 Seven bones articulate to make
each orbit:
1. Frontal
2. Zygomatic
3. Maxillary
4. Lacrimal
5. Ethmoid
6. Palatine
7. Sphenoid
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1
2
3
4
5
7
medial
lateral
superior
inferior
6

66. Osteology of the Orbit
 Optic canal- transmits the optic
nerve and ophthalmic artery
 Superior orbital fissure- transmits
CN III, IV, V1 & VI
 Inferior orbital fissure & groove-
transmits the infraorbital vessels &
nerve
 Anterior & posterior ethmoidal
foramina- transmits vessels &
nerves with same name
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Inferior
orbital
fissure &
groove
Optic canal
Superior
orbital
fissure
Ethmoidal
foramina

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