1. Anatomy of the skull
Dr Rania Gabr

2. Objectives List the bones of the skull
Identify the major sutures of the skull
Identify the major surface markings of the skull
Identify the major foramina in the skull
List the major structures which pass through the foramina
Describe the cranial fossa and its part
Understand the base of the skull and its fracture
Describe the structure of the mandible

3. The Skull It consists of flat and irregular bones It is divided into:
Cranial bones which encase the brain (Neurocranium)
Facial bones which form the bones of the face (Viscerocranium)

4. The Skull Cranial bones include: Facial bones include: (Neurocranium)
Frontal 1
Ethmoid 1
Sphenoidal 1
Occipital 1
Parietal 2
Temporal 2
Facial bones include:
(Viscerocranium)
Maxilla 2
Zygomatic 2
Nasal 2
Palatine 2
Lacrimal 2
Inferior conchae 2
Vomer 1
Mandible 1

7. The Skull
Frontal
Maxilla
Zygomatic
Nasal
Mandible
Lacrimal z

8. The Skull Parietal Temporal Squamous Mastoid Styloid Tympanic Petrous
Sphenoid
Greater wing
Lesser wing
Pterygoid process
Body
Occipital

9. The Skull Petrous part of temporal Lesser wing of sphenoid
Body of sphenoid
Pterygoid process
Ethmoid bone
Crista galli
Cribriform plate
Perpendicular plate
Vomer
Palatine bone

10. Frontal Bone Landmarks: Squama: flat portion that forms the forehead
Supraorbital margin: ridge under the eyebrow, forming the upper part of the orbit (eye socket)
Supraorbital foramen: small hole within supraorbital margin for blood vessels and nerves
Frontal sinuses: hollow spaces behind the squama, act as sound chambers to give the voice resonance.

11. Frontal Bone (Anterior View) (Blue Colored Bone)

12. Frontal Bone (Lateral View) (Blue Colored Bone)

13. Temporal bone

14. Temporal bone Landmarks:
Squama: flat portion of the temporal bone forming the anterior and superior part of the temple
Zygomatic process: process forming part of the cheek
Petrous portion: internal,between the sphenoid and occipital, forming part of the floor of the cranium. Contains the ear canal and internal ear structures.
Mandibular fossa: socket between squama and petrous portion, articulates with the condyle of the mandible (TMJ)
External auditory meatus: opening to the ear canal
Mastoid process: bony prominence behind the external auditory meatus
Styloid process: looks like an elephant’s tusk located between the mastoid process and the jaw. Acts as a point of attachment for muscles and ligaments.

15. Temporal Bone (Lateral View) (Purple Colored Bone)

16. Occiput
Landmarks:
Foramen magnum: large hole, allowing passage of the spinal cord
External occipital protuberance (EOP): prominent projection on back of occiput
Nuchal lines: a superior and inferior line running laterally from the midline, serve as a point of muscle attachment

17. Occipital Bone (Lateral View) (Orange Bone)

18. Occipital Bone (Posterior View) (Orange Colored Bone)

19. Sphenoid Bone

20. Sphenoid bone Landmarks
A prominent, irregular, wedge-shaped bone at the base of the skull. The sphenoid bone has been called the "keystone" of the cranial floor since it is in contact with all of the other cranial bones.
Landmarks
Greater wings: large lateral projections of bone that help to form the lateral border of the skull
Lesser wings: smaller lateral projections of bone above the greater wings
Pterygoid processes: two long downward projections from the greater wings that act as a point of muscle attachment.
Sella turcica: known as the Turkish Saddle which cradles the pituitary gland.

21. Sphenoid Bone (Lateral View) (Green Colored Bone)

22. Sphenoid Bone (Floor of Cranium) (Green Colored Bone)

23. Ethmoid Bone
An irregularly shaped, spongy bone that provides the floor of the front part of the skull and the roof of the nasal cavity.
The ethmoid consists of two masses of thin plates enclosing air cells and looks like a sieve.
Landmarks:
Lateral masses: form most of the wall between the nasal cavity and the orbits
Perpendicular plate: forms the superior portion of the nasal septum
Cribriform plate: forms the roof of the nasal cavity
Olfactory foramina: small holes within the cribriform plate for passage of the first cranial nerve (for smell)

24. Crista galli: upward extension of bone above the cribriform plate, acts as an anchoring point for one of the coverings of the brain. ( Falx cerebi)
Nasal conchae (turbinates): two scroll-shaped projections (superior and middle) with a mucus membrane on either side of the nasal septum. Function to cause air turbulence and trap inhaled particles.

25. Bones of the face Maxilla
The second largest bones of the face, after the mandible and form, by their union, the whole of the upper jaw.
They hold the upper teeth, and connect on the left and right to the zygomatic bones (cheek bones).
Each assists in forming the boundaries of three cavities, namely, the 1-roof of the mouth, 2-the floor and lateral wall of the nose, and 3- the floor of the orbit.

26. Maxilla

27. Landmarks:
Infra Orbital foramen: hole below the orbit, for blood vessels and nerves
Alveolar process:
arch of the maxilla containing the upper teeth
Palatine process: horizontal projection of the maxilla forming the anterior ¾ of the hard palate.

28. Zygomatic Bones Commonly referred to as the cheekbone.
It is situated at the upper
and lateral part of the
face: it forms the
prominence of the cheek
and part of the lateral wall
and floor of the orbit.
It articulates with the
zygomatic arch of the
temporal bone.

29. Vomer One of the unpaired facial bones of the skull. Located in
the midsagittal line,
and attaches to the
sphenoid, the
ethmoid, the left and
right palatine bones,
and the left and right
maxillary bones.

30. Inferior Nasal Conchae
Extends horizontally
along the lateral wall
of the nasal cavity
and consists of a
lamina of spongy
bone, curled upon
itself like a scroll.
Inferior Nasal Conchae

31. Smallest and most fragile bone of the face, is situated at the front part of the Medial of the orbit.
Contains the lacrimal sac and the naso-lacrimal duct.
Lacrimal Bones
Lacrimal bone

32. Nasal Bones Varying in size and form in different individuals
They are placed side by
side at the middle and
upper part of the face
and form, by their
junction, "the bridge" of
the nose

33. Cranial Fossa It is the cavity of the skull Divides into:
Anterior cranial fossa
Middle cranial fossa
Posterior cranial fossa

34. Anterior Cranial Fossa
Formed of:
Orbital plate of frontal bone
Cribriform plate of ethmoid
Crista galli
Lesser wing of sphenoid
Occupied by:
Frontal lobe of the cerebrum
Optic nerves
Olfactory bulb and tract

35. Middle Cranial Fossa Formed of: Greater wing of sphenoid
Body of sphenoid
Squamous part of temporal bone
Anterior part of petrous bone
It occupied by:
Temporal lobe of the cerebrum

36. Posterior Cranial Fossa
Formed of:
Sphenoid part of clivus
Posterior part of petrous bone
Occipital bone
It shows the following land marks:
Groove for transverse sinus
Groove for sigmoid sinus
Internal occipital protuberance
It is occupied by:
Cerebellum
Brain stem

37. Base of The Skull
Most of the bones are seen in other views

38. Foramina of the Skull Foramina are found within the skull bones
They vary in size and shape
They transmit nerves, blood vessels and dura matter

39. Foramina of the Skull

41. Foramina of the Skull
Supraorbital
Infraorbital
Mental

42. The following must be identified:
Nasion
Inion
Bregma
Lambda
External occipital protuberance
Parietal eminence
Zygomatic arch

44. Sutures of the Skull
Sutures are fibrous joints articulating the skull bones
They include:
Coronal
Sagittal
Lambdoid
Pterion

45. Skull Fontanelles
Fontanelles are spaces between some of the skull bones of infants.
They permit easy growth of the brain.
They permit overlapping of skull bones during labor.
They include:
1. Anterior Fontanelle
Lies between Frontal and Parietal Bones
Closed by 18 months of age
Posterior Fontanelle
Lies between Parietal and Occipital Bones
Closed by end of 1st year
3. Anterolateral Fontanelle
4. Posterolateral Fontanelle

46. The Mandible It is a flat bone Identify the following:
Head(condylar process)
Mandibular notch
Coronoid process
Ramus
Angle
Body
Mylohyoid line
Submandibular fossa
Digastric fossa
Mandibular foramen
Mental foramen

48. Thank u