This document provides an overview of skull anatomy and evaluation of plain x-rays of the skull. It describes the bones that make up the skull and their sutures and fontanelles. It outlines the indications for skull x-rays including evaluation of skeletal dysplasias, infections, tumors and metabolic bone diseases. Common x-ray views of the skull are described including lateral, frontal, Towne's and basal views. Abnormal findings on skull x-rays can include changes in density, contour, intracranial volume, calcifications and lucent defects. Specific conditions like craniosynostosis, anemia and fractures are discussed.

1. Evaluation of Plain X-ray Skull
A Systematic Approach
By
Dr. Tarek Mansour

3. • The skull is a rounded
layer of bone designed to
protect the brain from
penetrating injuries.

4. ANATOMY
• Formed of 22 bones
• 1 movable: Mandible.
• 21 fixed & articulating with
fibrous joints:
 5 unpaired: Ethmoid,
sphenoid, vomer, frontal and
occipital.
 8 paired: parietal, temporal,
zygomatic, lacrimal, maxillary,
nasal, palatine & inf. concha.

5. ANATOMY
• 1.Cranium: upper
and posterior
parts which
enclose the brain.
• 2.Facial skeleton:
anterior part of
the skull.

6. ANATOMY
BONES :
• Frontal bone anteriorly.
• Parietal bones on both
sides.
• Occipital bone
posteriorly.

7. ANATOMY
Sutures:
• Coronal suture
• Sagittal suture.
• Lambdoid suture.
• Range in size 1.5 mm. up
to 10 mm at birth. After
few ms, reach less than
3mm

8. ANATOMY
Fontanelles:
• Anterior (Bregma): 1.5y
• Posterior (lambda): 6ms.

9. ANATOMY
• Upper part: Frontal
bone.
• Middle part: 2
orbital cavities and
nasal cavity.
• Lower part: upper
and lower jaw.

10. ANATOMY
• BONES: Frontal bone, 2
zygomatic bones, nasal
bones, 2 maxillary bones,
mandible.
• SUTURES: fronto-nasal,
fronto-zygomatic, fronto-
maxillary, zygomatico-
maxillary.

11. ANATOMY
• Frontal process.
• Maxillary process.
• Temporal process.
• Orbital plate.

12. ANATOMY
• Frontal process.
• Zygomatic process.
• Alveolar process.
• Palatine process.
• Orbital plate.

13. ANATOMY
• Superiorly: nasal,
frontal and parietal
bones.
• Inferiorly: maxilla,
Zygomatic, gr. Wing of
sphenoid, sq. &
mastoid parts of
temporal bone and
occipital bone.

14. ANATOMY
PARTS:
Supra temporal area.
Temporal fossa.
Infra-temporal fossa.
Imp. Landmarks:
• Pterion.
• Asterion.
• Ext. aud. meatus.
• Mastoid process.
• Zygomatic arch

15. ANATOMY
BONES :
• 2 Parietal bones.
• 2 Mastoid temporal bones.
• Occipital bone.
Sutures:
• Lambdoid suture.
• Occipito-mastoid suture.

16. ANATOMY
• Divided in to anterior,
middle and posterior
parts by 2 lines:
Ant. Line along post.
Border of hard palate.
Post. Line through post.
Border of foramen
magnum.

17. ANATOMY
• Divided in to anterior,
middle and posterior
parts by 2 lines:
Ant. Line along post.
Border of hard palate.
Post. Line through post.
Border of foramen
magnum.

18. ANATOMY
Anterior Part:
• Hard palate:
• Anterior 2/3: palatine
process of maxilla.
• Posterior 1/3: palatine
bone.

19. ANATOMY
Anterior Part:
• Hard palate:
• Anterior 2/3: palatine
process of maxilla.
• Posterior 1/3: palatine
bone.

20. ANATOMY
Middle Part:
• Ant. mid: Vomer & body
of sphenoid.
• Ant. Lat.: pterygoid
process & Gr. wing of
sphenoid.
• Post. Lat.: petrous bone.
• Post. Mid: occipital bone.

21. ANATOMY
Posterior Part:
External occipital
protuberance.
Insertions of muscles .

22. ANATOMY
Imp. foramina:
F. Ovale : AMA, Mand. N
motor root of 5 th CN.
F. Spinosum : MMA.
Carotid canal : ICA.
Jugular F .: IJV, inf.
petrosal sinus, 9 th ,10 th
& 11 th CN.
F. Magnum..

23. ANATOMY

24. ANATOMY
• Divided into
anterior, middle
and posterior
cranial fossa.

25. ANATOMY
• Anterior cranial fossa:
Anterior :
• Orbital plates of frontal
bone.
• Cribriform plate of
ethmoid bone.
Posterior :
• Lesser wing of sphenoid,
• Planum sphenoidal.

26. ANATOMY
• Middle cranial fossa:
Middle :
• Sella Turcica (body of
sphenoid).
Sides :
• Gr. wing of sphenoid,
• Petrous temporal bone.
• Sq. temporal bone.

27. ANATOMY
• Posterior cranial fossa:
Anterior :
• Body of sphenoid articulating
with basilar part of occipital
bone ( Clivus ).
On sides :
• petrous and mastoid parts of
temporal bone.
Posterior :
• Squamous part of occipital one.

28. Blood Vessels of the Skull
• The brain requires a rich blood
supply, and the space between
the skull and cerebrum contains
many blood vessels.
• These blood vessels can be
ruptured during trauma,
resulting in bleeding.

30. Skull radiograph (X ray(.
Positions:
1.Lateral.
2.PA view.
3.Towne’s view.
4.Basal view.
Others:
o Optic foramen.
o Sinuses.
o Mastoids.
o Petrous bones.
o Coned pituitary fossa.

31. Indication for skull radiographs
• Evaluation of skeletal dysplasias.
• Diagnostic survey in abuse.
• Abnormal head shapes.
• Infections and tumors affecting the skull bones.
• Metabolic bone disease, leukemias and
• Multiple myeloma

32. X rays positions
• Lateral view of the skull.
• Frontal view.
• Towne`s view.
• Basal view.
• Water view.
• Caldwell`s view.

33. Lateral skull view
• Commonest plain x ray view
• Should examine:
1.Size & shape.
2.Thickness and density of the bone.
3.Sutures and vascular marking.
4.Base of skull and cranial cavity.

34. Lateral:
• Head in true lat position.
• Center over the pit. fossa (1 cm above OML
& 2.5 ant to EAM).

35. • Normal lateral view of skull
demonstrates the normal coronal
sutures, lambdoid sutures and the
vascular grooves due to middle
meningeal vessels posterior to coronal
sutures. Note the two lines formed by
the roof of the orbits ending
posteriorly at the anterior clinoid
processes. Arrow head marks the
tuberculum sellae. Vertical arrows
(anterior) show the cribriform plate
and the (posterior) planum
sphenoidale. Open arrow shows the
greater wing of sphenoid bone forming
anterior borders of middle cranial
fossa. The dorsum sellae (horizontal
arrow) with posterior clinoid processes
above and the clivus posteriorly are
well seen

36. Frontal (AP) view.
• OML should e vertical.
• PA with 20 degree caudal tilting.
• Center on the inion.

37. Frontal view
• PA view with 15° caudal
angulation demonstrates the
dense vertical bony projection
in the midline due to crista
galli, lesser wings of the
sphenoid on both sides joining
to form the planum
sphenoidale (arrow heads).
Floor of sella is faintly
visualized in the midline
(vertical arrows). Oblique line
of the orbit is formed by the
greater wing of sphenoid in its
lower two-thirds and by the
frontal bone in its upper one-
third

38. Towne’s view:
• AP with 30 degree caudal tilting.

39. Towne`s view
• Towne’s view shows
foramen magnum in the
center with dorsum sellae
projecting through it. The
parallel lucencies (short
arrows) on either side
represent the internal
auditory canals. Further
laterally pneumatized
mastoids air cells can also
be seen

40. Basal (PA) view:
• Hyperextension of he head.
• Anatomical base line horizontal.
• Center vertical to it & between angles of
mandible.

41. Basal view
• Basal view of skull shows the
nasopharynx, sphenoid sinus and
ethmoid sinuses in the midline.
Posteriorly odontoid process is seen to
project into the foramen magnum
posterior to the arch of atlas. Laterally,
the foramen ovale (open arrow)
foramen spinosum, (long arrow),
eustachian tube posterior to foramen
spinosum and the carotid canal are
well visualized. Antero-laterally, the
three lines formed by the posterior
wall of orbit (arrow head) maxillary
sinus (S-shaped) (curved arrow) and
the anterior wall of middle cranial
fossa (thick arrow) (arched shadow
with concavity posteriorly) should be
looked for in each case. Medial and
lateral pterygoid plates are well seen

42. Sinuses.
• They are rudimentary at
birth and increase in
size with age, reaching
full development in
adult skull.
• Anterior and posterior
groups.
• Variations &
pneumatization.

43. Waters view
• Waters view of skull
shows bilateral maxillary
antrum (lower horizontal
arrows), frontal sinuses
(vertical arrows),
ethmoid sinuses (upper
horizontal arrows) and
lower margin of sphenoid
sinuses (arrowheads)

44. • Pineal.
• Choroid plexus.
• Dura (Falx, tentorium, over vault).
• Ligaments.
• BG.
• Pit. gland.
• Lens.

46. Skull plain x ray abnormalities
Skull X-rays can be categorized in the following groups:
1.Abnormal density
2.Abnormal contour of the skull
3.Abnormal intracranial volume
4.Intracranial calcification
5.Increased thickness of the skull
6.Single lucent defect
7.Multiple lucent defects
8.Sclerotic areas.

48. Abnormal skull contour
Normal skull contour is maintained by:
• Sutures.
• Intracranial contents.
• Normal bone formation.
• Craniosynostosis is the commonest cause of abnormal
skull contour.
• A simple method of assessing the size of the skull is to
compare the skull vault to the size of the face.
At birth 4:1
At 2 years 3:1
At adulthood 1.5:1

50. • It is important to differentiate premature closure
of all sutures from microcephaly with fused
sutures.
• When multiple sutures fuse prematurely
1- The suture not fuse symmetrical so it result in
irregular skull.
2- Signs of raised intracranial tension.
3- Exaggerated convolutional marking.

51. • Craniosynostosis: AP view of
skull shows silver beaten
appearance due to exaggerated
convolutional markings all
over the skull vault. None of
the sutures are seen

52. • Hemolytic anemia (thalassemia) caused.
• 1- Wide diplioc space with striking radial
striation (hair-on-end) appearance.
• 2- Obliterated paranasal sinuses.
• Other forms of anemia shows the same changes
but less marked (sickle cell disease, hereditary
spherocytosis).

53. • Thalassemia: Lateral skull
radiograph shows widened
diploic space with coarsened
trabeculae giving “hair-on-
end” appearance typical of
hemolytic anemia

54. Single radiolucent defect
If lytic lesion noted we should evaluate:
• Location.
• Associated soft tissue.
• Involved skull table.
• Margin
Sharp.
Ill defined.
Sclerotic.

56. • Craniolacunia: Lateral skull
radiograph in an infant shows
multiple lucencies with
intervening dense areas typical
of craniolacunia.
• Note the associated occipital
encephalocele and absence of
sutural widening

57. • Depressed fracture: Frontal
radiograph shows the parallel
dense lines due to depressed
bone fragments and associated
lucency due to absence of bone

58. • Growing fracture: PA skull
radiographs in a child
demonstrate fracture of the
right frontal bone with
thickening, sclerosis and wide
separation of the fracture
ends. Note the soft tissue
swelling overlying this area

59. • Dermoid scalp. Skull
radiograph shows a well
circumscribed lucency
overlying the coronal suture

60. Osteosarcoma: (A) Large lytic area with irregular
margin is seen affecting the left parietal bone. (B) CT scan of the
same patient shows the soft tissue swelling, destruction of the bone
and extradural extension of the tumor

62. • Diffuse metastasis of skull
vault: Lateral skull radiograph
shows multiple lytic areas
involving both tables of skull
and diploic space. Note
widening of coronal suture
also

63. • Multiple myeloma: Lateral
skull radiographs shows
multiple well-defined punched
out lytic lesions affecting the
skull vault as well as mandible
typical of myeloma

64. Hyperparathyroidism: Lateral
skull radiograph shows
multiple lytic lesions with
mottled appearance
Hyperparathyroidism: Lateral skull
radiograph shows multiple well
circumscribed rounded lytic lesions
involving skull vault with bone
within bone appearance an unusual
feature of hyperparathyroidism

65. Sclerotic areas of the skull
• Osteopetrosis.
• Fibrous dysplasia.
• Paget disease.
• Rickets.
• Osteoma.
• Meningioma.
• Hyperostosis frontalis interna.

66. • Osteopetrosis: Frontal
radiograph shows diffuse
increased density affecting all
bones of the skull vault as well
as base

67. Sphenoid wing meningioma: (A) PA view of skull shows hyperostosis of
the left lesser and greater wings of the sphenoid bone typical of
meningioma. (B) Contrast enhanced CT scan in the same patient
shows proptosis and hyperostosis of sphenoid wings with enhancing
extradural mass due to meningioma on the left side

68. Fibrous dysplasia: Frontal view of skull reveal sclerotic
lesion involving the frontal bone. The frontal sinus is
opaque. Axial CT scan in the same patient shows
expanded sclerotic frontal bone

69. Paget disease: Lateral view of
skull reveal focal areas of
opacities in previous areas of
osteoporosis giving “cotton
wool” appearance
Osteoma: Waters view of skull
shows osteoma of the frontal
sinus

70. • Hyperostosis frontalis
interna: Lateral skull
radiograph shows irregular
thickening of the frontal bone
in an elderly female. The inner
table is involved more than the
outer table with sparing of
diploic spaces

72. Sturge-Weber syndrome: PA (A) and lateral (B)
view of the skull shows gyriform calcification on
the left side