This document provides an overview of skull osteology and structures. It discusses the 14 bones that make up the calvaria/brain case and 14 bones of the facial skeleton. Key structures of individual bones like the occipital, parietal, frontal, nasal, maxilla, mandible are described. Clinical implications of fractures to these bones are mentioned. Different views of the skull like norma verticalis, occipitalis, frontalis and lateralis are explained along with the bones and sutures seen in each view. Structures passing through various foramina are listed. Temporal lines, zygomatic arch, and styloid process are also described.

2. OSTEOLOGY OF SKULL
DR.MEHER MOIN KHAN
LECTURE 1- BASIC OSTEOLOGY
Reference book B.D

3. CONTENTS
Introduction
Anatomical position of skull
Calvaria or brain case
Facial skeleton
Joints of skull
Methods of studying skull
Clinical importance
Cervical vertebrae
Clinical implications
3

4. INTRODUCTION
• Brain is the highest seat of intelligence
• Head and neck is the uppermost part of the body
• Head comprises of skull brain , meninges
hypophysis cerebri
special senses , teeth and blood vessels
4
Shakespeare --Uneasy Lies in t h e head t h a t w e a r s t h e crown

5. SKULLCONSISTES OF 28 BONES
• The CALVARIA ORBRAIN CASE consists of 14 bones
• The f a c i a l s k e l e t o n consists of
14 bones
5

6. CALVARIA OR BRAIN CASE
P a i r e d
1. Parietal (2)
2. Temporal (2)
3. Malleus (2)
4. Incus (2)
5. Stapes (2)
Unpaired
1. Frontal (1)
2. Occipital (1)
3. Sphenoid (1)
4. Ethmoid (1)

7. THE FACIAL SKELETON
PAIRED
1. Maxilla (2)
2. Zygomatic (2)
3. Nasal (2)
4. Lacrimal (2)
5. Palatine (2)
6. Inferior nasal
conchae (2)
UNPAIRED
1. Mandible (1)
2. Vomer (1)

8. ANATOMICAL POSITION OF SKULL
• The skull can be placed in proper orientation by
considering any one of the two planes ;
1.Reid's B a s e Line is a horizontal line obtained by joining
the infraorbital margin to the centre of the external acoustic
meatus , i.e. Auricular point.
2.The F r a n k f u r t H o r i z o n t a l P l a n e of orientation is
obtained by joining the infraorbital margin to the upper
margin of the external acoustic meatus
8

9. JOINTS OF THE SKULL
• Sutures
• Few primary cartilaginous
• Three pair of synovial joints
(2 between ear ossicles
1 is the largest TMJ)
9

10. • Plane
• Serrate
- Internasal
- Coronal
• Denticulate - Lambdoid
• Squamous -
Parietotemporal
• Gomphosis – PDL
•Schindylesis – Ala of Vomer
(wedge groove joint)
10

11. • Ve r t e x – highest point on sagittal suture
• Va u l t – arched roof for dome ofskull
11
TERMINOLOGIES
P a r i e t a l t u b e r (eminence) –
area of maximum convexity of parietal
bone
most common site of fracture of skull

12. •Br egma / a n t e r i o r f o n t a n e l l e –
meeting point of coronal and sagittal (18
to 24 month )
•Lambda / p o s t e r i o r f o n t a n e l l e –
sagittal and lambdoid suture
(2 to 3 months of age)
12
FRONTANELLE

13. • PARIETAL FORAMEN – one on each side,
of the parietal bone
2.5 cm to 4 cm in front of
lambda
• OBELION– point on sagittal suture
between two parietal foramen
13

14. METHODSOF STUDYING SKULL
• The skull can be studied as a whole
• Can be studied from outside or externally in different views:
Superior view or NORMA VERTICALIS
Posterior view or NORMA OCCIPITALIS
Anterior view or NORMA FRONTALIS
Lateral view
Inferior view
or NORMA LATERALIS
or NORMA BASALIS
14

15. • The skull can be studied internally or from inside after
removing the roof of the Calvaria or skull cap
a. Internal surface of cranial vault
b. Internal surface of cranial base ,
natural subdivision into
Anterior – middle – posterior cranial fossae
15

16. • The skull can also be studied as
individual bones
Mandible
Maxilla
Ethmoid
Zygomatic
Sphenoid
Vomer etc
16

17. NORMAVERTICALIS
• How the skull looks from above
• Usually oval in shape
• Wider posteriorly than anteriorly
• Shape maybe more nearly circular
17

18. • Upper part of f r o n t a l boneanteriorly
• Uppermost part of o c c i p i t a l bone posteriorly
• P a r i e t a l bone on eachside
18
BONES SEEN

19. SUTURES SEEN IN NORMA
VERTICALIS
• CORONAL: placed between the frontal bone and
two parietal bones
• SAGGITAL : median plane between two
Parietal bones
• LAMBDOID: lies posteriorly between two
parietal bones runs
downwards and forwards
across the cranial vault
19

20. METOPIC SUTURE
• Only suture which normally closes during infancy
• Present in 3% to 8 % individuals
• Lies in median plane
• Separates 2 halves of frontal bone
• Fuses at 6 yrs of age
• May persist throughout life and may be
mistaken for a fracture
20

21. 28

22. BONES SEEN
29
Posterior parts of parietal bone
above
Upper part of Squamous part of
occipital bone
Mastoid part of temporal bone on
each side

23. SUTURES SEEN INNORMAOCCIPITALIS
• LAMDOID SUTURE
• OCCIPITOMASTOID SUTURE
• PAREITOMASTOID
• S a g i t t a l s u t u r e – posterior part
30

24. OCCIPITAL BONE
• Cranial dermal bone and the main bone of the occiput
(back and lower part of the skull)
• Trapezoidal in shape
• Curved on itself like a shallow dish
• Overlies the occipital lobes of the cerebrum
The foramen magnum
is the largest of the cranial foramina.
It lies in the occipital bone within the posterior cranial fossa, and allows the
passage of the medulla and meninges, the vertebral arteries, the anterior
and posterior spinal arteries and the dural veins.
The spinal division of the accessory nerve ascends through the foramen
magnum to join the cranial division
31

25. PARIETAL BONE
• The parietal bones are two bones in
the skull which, when joined together at a
fibrous joint, form the sides and roof of the
cranium
• Roughly Quadrilateral
has two surfaces
four borders
four angles
32

26. ANTERIOR VIEW (NORMA
FRONTALIS)
33
The anterior view of the skull
includes the
1. Forehead superiorly
2. Inferiorly the orbits
3. The nasal region
4. The part of the face
between the orbit And the
upper jaw
5. The upper jaw
6. Lower jaw

27. FRONTAL BONE
The forehead consists of the frontal
bone, which also forms the superior
part of the rim of each orbit
Just superior to the rim of the orbit on
each side are the raised
s u p e r c i l i a r y a r c h e s
Rounded curved elevation above the
medial part of each orbit
34

28. Between these arches is a small
depression
(THE GLABELLA)
NASION – median point at root of nose
where internasal suture meets
frontonasal
suture
Clearly visible in the medial part of the
superior rim of each orbit is the supra-
orbital foramen ( s u p r a - o r b i t a l
not ch)
35

29. ORBITAL OPENINGS
• Roughly quadrangular
• FOUR MARGINS
 SUPRA ORBITAL –
 INFRAORBITAL –
 MEDIALORBITAL –
Frontal bone Zygomatic
laterally and maxilla
medially
frontal bone above and
lacrimal crest below
 LATERAL ORBITAL–Frontal process of Zygomatic
and zygomatic process of
frontal bone
36

30. VOMER
• One of the unpaired facial bones of the
skull
• It is located in the midsagittal plane
• Articulates with the Sphenoid
the Ethmoid
left/right Palatine bones
left/right Maxillary bones
• Forms the inferior part of the Nasal septum,
with the superior part formed by
the perpendicular plate of the Ethmoid
bone
37

31. NASAL BONE
2 small oblong bones
varying in size and form in different individuals
placed side by side at the middle and upper part
of the face
by their junction form the bridge of the nose
The nasal articulates with four bones:
Two of the cranium, the Frontal , the Ethmoid
Two of the face, the opposite nasal and
the Maxilla
38

32. CLINICALANATOMY
•The nasal bone is most commonly fracture
Because of trauma and projection of nose
• Followed by mandible and parietal eminence
39
Therole of multidetector computerized tomography inevaluation of maxillofacial fractures
Article inEgyptian Journalof Radiology and Nuclear Medicine · January 2013

33. MANDIBLE(LOWER JAW)
• L a r g e s t and S t r o n g e s t bone of face
• Develops from the 1st pharyngeal arch
• Horse shoe shaped body - lodges the teeth
• Pair of Rami which provides attachments to
Muscles o f Mastication
40

34. BODYOFMANDIBLE
OUTER S u r f a c e
• Symphysis menti - Line at which the right/left
half of the mandible meet
• M e n t a l p r o t u b e r a n c e – median triangular
projecting in lower part of midline
• M e n t a l f o r a m e n – lies below between
two premolars
• Oblique line- sharp continuation of
anterior border of ramus running
downwards & forwards
41

35. INNER SURFACE
1.Mylohyoid line - prominent ridge runs Obliquely
downwards/forwards from 3rd molar to Median area
below genial tubercles
2. Submandibular f o s s a – lodges
Submandibular gland below Mylohyoid line
3 . Sublingual f o s s a – Sublingual gland above
Mylohyoid line
42

36. 4. Posterior surface of Symphysis menti
is marked by four elevation called
Superior & I nfer i or Genial Tu b e r c l e s
5. Mylohyoid g r o o v e
Extends on body below posterior end of
Mylohyoid line
43

37. MANDIBULAR FRACTURES
44
• Most condylar fractures are result
of blunt trauma to the anterior mandible
• Forces are transmitted to the condylar
region
• Where posterior movement of mandible is
limited by Glenoid fossa , TMJ capsule ,
Insertion of Lateral pterygoid
• Where forces overcome strength of
condyle fracture occurs

38. THE
MAXILLA
• Contributes a large share in the formation of
facial skeleton
• Anterior surface of body of maxilla presents
Nasal notch medially
Anterior nasal spine
Infraorbital foramen 1cm below infraorbital margin
Incisive fossa above incisor teeth
Canine fossa lateral to canine eminence
45

39. PROCESSES OF MAXILLA
• FRONTALPROCESS – Directed upwards
Articulates anteriorly with
nasal bone
Posteriorly with lacrimal bone
Superiorly with frontal bone
• ZYGOMATICPROCESS – short stout articulates
with
the zygomatic bone
• ALVEOLAR PROCESS – bears socket for teeth
46

40. SUTURES OF NORMA FRONTALIS
• Frontonasal
• Internasal
• Zygomaticofrontal
• Intermaxillary
• Zygomaticomaxillary
• Nasomaxillary
• Lacrimomaxillary
47

41. STRUCTURES PASSING THROUGH
FORAMINA
FORAMINA VESSELS / NERVES
Supraorbital notch/foramen Supraorbital nerves and vessels
Infraorbital foramen Infraorbital nerves and vessels
Zygomaticofacial foramen Zygomaticofacial ( MAXILLARY NERVE)
Mental foramen Mental nerve and vessels (MANDIBULAR NERVE)
48

42. LATERAL VIEW (NORMA
LATERALIS)
49
• Bones forming the lateral portion include
the frontal, parietal, occipital,
sphenoid, and temporal bones.
•Bones forming the visible part of the
facial skeleton include the nasal, maxilla,
and zygomatic bones.
• The mandible forms the visible part of
the lower jaw.

43. TEMPORAL LINES
50
Crossing the middle of the parietal
bone in an arched direction are two
curved lines, the superior and inferior
temporal lines
The former gives attachment to the
temporal fascia
latter indicates the upper limit of the
muscular origin of the temporal muscle

44. SUTURES OF NORMA LATERALIS
• LAMDOID SUTURE
Sutural or wormian bones common
• OCCIPITOMASTOID SUTURE
• PAREITOMASTOID
• c o r o n a l SUTURE
51

45. ZYGOMATICARCH OR ZYGOMA
• The zygomatic arch, or cheek bone, is formed
by the zygomatic process of the temporal bone
and the temporal process of the zygomatic bone
(the side of the cheekbone)
• The two being united by an oblique suture
(zygomaticotemporal suture)
• The tendon of the temporalis passes medial to
the arch to gain insertion into the coronoid
process of the mandible
52

46. • Above the zygomatic arch is
the TEMPORALFOSSA which is
filled by TEMPORALIS MUSCLE
• Attached to lower margins is
MASSETER MUSCLE
• Contraction of both can be felt
by clenching the teeth
53

47. STYLOID (TEMPORAL)PROCESS
54
• The styloid process is a process of
bone that extends down from the
TEMPORAL BONE of the human skull
just below the ear
• Serves as an anchor point for several
muscles associated with the TONGUE
and LARYNX

48. REINS OF CHARIOT
• Its Proximal Part (TYMPANOHYAL) is ensheathed by
the tympanic part of the temporal bone
• Its distal part (STYLOHYAL) gives attachment to
the following:
• STYLOHYOID LIGAMENT
• STYLOMANDIBULAR LIGAMENT
• STYLOGLOSSUS(HYPOGLOSSAL NERVE)
• STYLOHYOID (FACIAL NERVE)
• STYLOPHARYNGEUS (GLOSSOPHARYNGEAL NERVE)
55

49. EAGLES SYNDROME (STYLOHYOID
SYNDROME)
• rare condition commonly characterized
• sudden, sharp nerve-like pain in the jaw
bone and joint, back of the throat, and base of the
tongue, triggered by swallowing, moving the jaw, or
turning the neck
• elongated or misshapen styloid process (the
slender, pointed piece of bone just below the
ear) and/or calcification of the stylohyoid
ligament
56

50. 57

51. CLINICALANATOMY
• In road side accidents
a n t e r i o r division o f middle meningeal a r t e r y
may be ruptured clot formation between
skull bone and duramater /extradural haemmorhage
• This clot compresses motor area causing paralysis of
opposite side
• Clot must be sucked out earliest by trephination
58

52. NORMABASALIS
BASE OFTHE SKULL
1. Hard palate
2. Sphenoid
3. Vomer
4. Temporal bone with Squamous
And mastoid portions
5. Occipital bone
59

53. HARD PALATE
• Bounded in front and laterally by the alveolar
process
• Has two bones , palatine process of maxilla and
palatine bone
• Two palatine process joined by median palatine
sutures
• And with palatine bone by transverse palatine
suture
• Posterior limit is posterior nasal spine
60

54. FORAMEN OF HARD PALATE
• Behind incisors, INCISIVE
foramen
• Posterolaterally we have
GREATER PALATINE foramen
Transmits descending palatine
vessels and anterior palatine
nerves
• Behind is LESSER PALATINE
foramen
61

55. THE SPHENOID BONE
62
It has
 Medial and lateral pterygoid process
 Under surface of two great wings
Lateral to the medial plate is SCAPHOID
Fossa , origin of tensor veli palati muscle
Lower extremity has pterygoid hamulus around which the tendon of muscle turns
THE BAT WITH EXTENDEDWINGS

56. • The greater wing of sphenoid has three foramen
 Foramen ROTUNDUM
Foramen OVALE
Foramen SPINOSUM

57. FORAMINA CONTENTS
Foramen Rotundum Maxillary nerve
Foramen Ovale Lesser petrosal
Acessory meningeal artery
Mandibular nerve
Emissary vein connecting cavernous sinus with
pterygoid plexus of veins
Foramen Spinosum Middle meningeal artery and vein
Meningeal branch of Mandibular nerve
Foramen Lacerum During life, filled with cartilage
Jugular Foramen CN IX X XI
Inferior petrosal and sigmoid sinus
Meningeal branch of ascending pharyngeal
and occipital arteries
64

58. OCCIPITAL BONE
65
FORAMEN MAGNUM
Through the narrow anterior part
a) Apical ligament of dens
b) Vertical band of cruciate ligament
c) Membrana tectoria
Through the wide posterior part
a) Lower part of medulla oblongata
b) Three meninges

59. • Through the SUBARACHNOID space
a) Spinal accesory nerves
b) Vertebral arteries
c) Sympathethic plexus around the
vertebral arteries
d) Posterior spinal arteries
e) Anterior spinal artery
66

60. CERVICAL VERTEBRAES
67

61. CLINICALANATOMY
• Fontanelles are sites of growth , permitting growth of brain
• Helps to determine age
brain growth is stunted such• If Fontanelles fuse early
children's are less intelligent
• Bones over riding at fontanelle helps to decease size of head during
delivery
21

62. ANTERIOR FONTANELLE
BULGING
RAISED
INTRACRANIAL
PRESSURE
DEPRESSED
DECREASED
HYDRATION/
DEHYDRATION
22

63. • prolonged elevated intracranial pressure
prolonged papilloedema
cognitive impairment and impaired vision
• Fundoscopy should always be performed during the physical
examination of children with craniosynostosis
23

64. Cappput succdeneum
• soft tissue swelling at any part of skull
due to ruptured capillaries
• Pitting is hallmark feature
• Skull becomes normal within few days
24

65. CRANIOSYNOSTOSIS
25
• Coronal sagittal lambdoid suture are
supposed to close at 22 to 39 months of
age
VIRCHOWS LAW
When premature closure occurs ,
growth of skull is restricted
perpendicularly to the fused
suture and enhanced in a plane
parallel to it
PANSYNOSTOSIS
All sutures closed (in practice 3 or more)

66. ASSOSIATED SYNDROMES
APERT SYNDROME
Acrocephlosyndactyly type 1 , small upper jaw
fusion of fingers and toes
26
CROUZONS SYNDROME
Acrocephlosyndactyly type 2
Bilateral coronal fusion, flat cheek , flat nose ,
exopthalmos, hypertelorism , hypoplastic maxilla

67. PFEIFFER SYNDROME –
Acrocephlosyndactyly type 3
abnormalities of skull
hands and feet wide set, bulging eyes
hypoplastic maxilla, beaked nose
SAETHRE – CHOTZEN SYNDROME
Acrocephlosyndactyly type 5
short broad head, hypertelorism , droopy eyelids
Fingers abnormally short and webbed.
27

68. INTRODUCTION
There are 7 cervical vertebrae's which form the bony network of the neck
THREE are atypical
THREE TO SIX aretypical (4)
Characterised by the presence of
FORAMINATRANSVERSARIA
68

69. CHARACTERISTICS OF TYPICAL
VERTEBRAE
• Small bodies
• Bifid spinous process
• Transverse process that contain a
foramen (FORAMENTRANSVERSARIUM)
69

70. ATYPICAL
VERTBRA
ES
FIRST CERVICALVERTEBRAE
70

71. IDENTIFICATIONS
• Ring shaped
• Neither body nor spine
• Short anterior arch
• Long posterior arch
• Right/left lateral masses
• Transverse process
71

72. • ANTERIOR ARCH Is marked by
median anterior tubercle on anterior aspect
• Posterior surface bears
Oval facet which articulates with dens
•POSTERIOR ARCH Forms 2/5th of ring
Much longer than anterior arch
•Posterior surface is marked by
Median posterior tubercule
72

73. SECONDCERVICALVERTEBRAE
73
•Called AXIS
•Characterized by presence of dens or
odontoid process
•Usually believed to represent
Centrum or body of atlas which has
fused with the Centrum of axis

74. SEVENTH CERVICAL VERTEBRAE
• Ve r t e b r a e prominens
•Long spinous process at tip
Can be felt through skin
At the lower end of nuchal furrow
• Spine thick long nearly horizontal
• Not bifid but ends in tubercle
74

75. CLINICALANATOMY
• During ju d icial hanging
The odontoid process usually
breaks to hit
upon the vital centers in the
medulla oblongata
75

76. • HANGMANSFRACTURE occurs due to
fracture of pedicle of axis vertebrae
• As vertebral canal gets enlarged spinal
cord does not get pressed
76

77. • Prolapse of intervertebral discs occurs at
the junction of different curvatures
• Most common site Is l o w e r c e r v i c a l
upper l u m b a r vertebral regions
• Pharyngeal ad retropharyngeal inflammation
may cause decalcification of atlas
• This may lead to loosening of attachments of
transverse ligament which may eventually
yield, causing SUDDENINFANT DEATH
SYNDROME
77

78. OCCIPITALISATION/ ASSIMILATION
• The Atlas May Fuse With The Occipital Bone
This Is Called OCCIPITALISATION Of Atlas
• May Compress The Spinal Cord Which
Requires Surgical Decompression
78

79. SKELETAL MATURITY EVALUATION
79
HASSELAND FARMAN
STAGE ONE INITIATION
• 80 to 100% growth expected
• lower border c2 c3 c4 flat
• Wedge shaped vertebrae
• Superior border tapered from
posterior to anterior
STAGE TWO a c c e l e r a t i o n
• 65 to85% growth expected
• Nearly rectangular
• Concavities starts developing at
inferior border

80. STAGE THREE t r a n s i t i o n
• 25 to 65% growth expected
• Rectangular in shape
• Distinct concavities seen in inferior borders of c2 c3
• A concavity starts beginning at c4
STAGE FOUR d e c e l e r a t i o n
• 10 to 25% growth expected
• Distinct concavities seen in inferior borders of c2 c3 c4
• Square shaped
80

81. • STAGE FIVE m a t u r a t i o n
• 5 to 10%
• Nearly square
• Accentuated concavities seen in c2 c3 c4
• STAGE SIX completion
• little of no growth
• Square in shape
• Deep concavities in c2 c3 c4
81

82. CONCLUSION
• Osteology of head and cervical vertebrae helps us to determine growth of
individual
• Age determination and serves as reliable indicators of skeletal maturity
• Bone morphology
• Types and patterns of fractures
82

83. REFERENCES
• BDC Human Anatomy - Head, Neck & Brain (Volume 3)
• Gray's Anatomy for Students 3rd Ed
83

84. THANK YOU
84