Base of the Skull 33

Base of the skull (from below). The individual bones are

indicated by different colors.

Skull of the newborn (inferior aspect).

A = pterygoid canal

B = foramen ovale

C = internal carotid artery within carotid canal and internal

jugular vein within the venous part of jugular foramen

D = stylomastoid foramen (facial nerve)

E = jugular foramen (glossopharyngeal, vagus and

accessory nerves)

F = hypoglossal canal (hypoglossal nerve)

1 Incisive canal

2 Median palatine suture

3 Palatine process of maxilla

4 Palatomaxillary suture

5 Greater and lesser palatine foramina

6 Inferior orbital fissure

7 Middle concha (process of ethmoidal bone)

8 Vomer

9 Foramen ovale

10 Groove for auditory tube

11 Pterygoid canal

12 Styloid process

13 Carotid canal

14 Stylomastoid foramen

15 Jugular foramen

16 Groove for occipital artery

17 Occipital condyle

18 Condylar canal

19 Nuchal plane

20 External occipital protuberance

21 Zygomatic arch

22 Lateral pterygoid plate

23 Medial pterygoid plate

24 Mandibular fossa

25 Pharyngeal tubercle

26 Superior nuchal line

27 Mastoid process

28 Inferior nuchal line

29 Mastoid notch

30 Foramen magnum

31 Incisive bone or premaxilla (dark violet)

32 Maxilla (violet)

33 Palatine bone (white)

34 Vomer (orange)

35 Sphenoidal bone (red)

36 Zygomatic bone (yellow)

37 Temporal bone (brown)

38 Occipital bone (blue)

39 Palatine process of maxilla

40 Vomer

41 Sphenoidal bone

42 Petrous part of temporal bone

43 Basilar part

44 Lateral part of occipital bone

45 Squamous part

46 Mandible

47 Zygomatic arch

48 Choana

49 Pterygoid process of sphenoidal bone

50 Carotid canal

51 External acoustic meatus (tympanic anulus)

52 Sphenoidal fontanelle

53 Parietal bone

54 Mastoid fontanelle

1

20 3 21 25 26

34 Base of the Skull

Canals, fissures, and

foramina of the base of the

skull

1 Superior orbital fissure

2 Foramen rotundum

3 Optic canal

4 Foramen ovale

5 Foramen spinosum

6 Internal acoustic meatus

7 Jugular foramen

8 Foramen magnum

Bones

9 Frontal bone (orange)

10 Ethmoidal bone (dark green)

11 Sphenoidal bone (red)

12 Temporal bone (brown)

13 Parietal bone (yellow)

14 Occipital bone (blue)

Details of bones

15 Crista galli

16 Cribriform plate

17 Digitate impressions

(frontal bone)

18 Lesser wing of sphenoidal

bone

19 Foramen lacerum

20 Hypophysial fossa

(sella turcica)

21 Anterior clinoid process

22 Trigeminal impression

23 Petrous part of temporal

bone

24 Groove for sigmoid sinus

25 Dorsum sellae

(posterior clinoid process)

26 Greater wing of sphenoidal

bone, groove for middle

meningeal artery

27 Hypoglossal canal

Base of the skull (internal aspect, oblique lateral view from left side).

Base of the skull (internal aspect, superior view).

Individual bones indicated by color.

Skull of the Newborn 35

Cranial skeleton

1 Frontal tuber or eminence

2 Parietal tuber or eminence

3 Occipital tuber or eminence

4 Squamous part of temporal bone

5 Greater wing of sphenoidal bone

Facial skeleton

6 Maxilla

7 Mandible

8 Zygomatic bone

9 Nasal bone

Sutures and fontanelles

10 Frontal suture

11 Coronal suture

12 Sagittal suture

13 Lambdoid suture

14 Anterior fontanelle

15 Posterior fontanelle

16 Sphenoidal (anterolateral) fontanelle

17 Mastoid (posterolateral) fontanelle

Base of the skull

18 Frontal bone

19 Ethmoidal bone

20 Sphenoidal bone

21 Hypophysial fossa (sella turcica)

22 Dorsum sellae

23 Temporal bone

24 Mastoid (posterolateral) fontanelle

25 Occipital bone

Skull of the newborn (anterior aspect).

Skull of the newborn (lateral aspect). Base of the skull of the newborn (internal aspect).

In the newborn, the facial skeleton, in contrast to the

cranial skeleton, appears relatively small. There are no teeth

presenting. The bones of the cranium are separated by wide

fontanelles.

Skull of the newborn (superior aspect). Calvaria.

36 Median Sections through the Skull

Median section through the skull, right half (internal aspect).

1 Hypophysial fossa (sella turcica)

2 Anterior clinoid process

3 Frontal bone

4 Ethmoidal air cells

5 Sphenoidal sinus

6 Superior concha

7 Middle concha

8 Maxillary hiatus

9 Inferior concha

10 Inferior meatus

11 Anterior nasal spine and maxilla

12 Mental spine or genial tubercle

13 Groove for middle meningeal artery

14 Dorsum sellae

15 Internal acoustic meatus

16 Groove for sigmoid sinus

17 Hypoglossal canal

18 Occipital condyle

19 Condylar process

20 Lateral pterygoid plate of pterygoid process 21 Medial pterygoid plate

22 Lingula of mandible

23 Mandibular foramen

24 Mylohyoid groove

25 Mylohyoid line

26 Submandibular fovea

1

Median Sections through the Skull 37

Facial part of the skull (viscerocranium), divided in two halves (lateral and medial

aspect). Right inferior concha has been removed to show the maxillary hiatus.

Left maxillary sinus opened.

Median section through the skull. The nasal septum has been removed.

Bones indicated by colors.

1 Frontal sinus

2 Frontal bone

3 Crista galli

4 Nasal bone

5 Sphenoidal sinus

6 Superior concha of ethmoidal

7 Middle concha bone

8 Frontal process

of maxilla

9 Ethmoidal bulla

10 Uncinate process

11 Maxillary hiatus

12 Palatine bone

13 Greater palatine foramen

14 Alveolar process of maxilla

15 Central incisor

16 Zygomatic bone

17 Ethmoidal bone

18 Lacrimal bone

19 Pterygopalatine fossa

20 Maxillary sinus

21 Lateral pterygoid plate

22 Medial pterygoid plate

23 Third molar tooth

24 Pterygoid hamulus

25 Two premolar teeth

Bones (indicated by colors)

1 Frontal bone (yellow)

2 Nasal bone (white)

3 Ethmoidal bone (dark green)

4 Lacrimal bone (yellow)

5 Inferior nasal concha (pink)

6 Palatine bone (white)

7 Maxilla (violet)

8 Mandible (white)

9 Parietal bone (light green)

10 Temporal bone (brown)

11 Sphenoidal bone (red)

12 Petrous part of temporal

bone (brown)

13 Occipital bone (blue)

14 Ala of vomer (light brown)

Because of the upright posture that the human developed

in the course of evolution, the cranial cavity greatly

increased in size, whereas the facial skeleton decreased. As

a result, the base of the skull developed an angulation of

about 120° between the clivus and the cribriform plate (see

drawing on page 19). The hypophysial fossa containing the

pituitary gland lies at the angle formed between these two

planes.

1

38 Disarticulated Skull II: Ethmoidal Bone

Ethmoidal bone

1 Crista galli

2 Cribriform plate

3 Ethmoidal air cells

4 Middle concha

5 Perpendicular plate (part of nasal septum)

6 Orbital plate

Sphenoidal bone

7 Lesser wing

8 Greater wing

9 Anterior clinoid process

10 Posterior clinoid process

11 Foramen ovale

12 Foramen spinosum

13 Lingula of the sphenoidal bone

14 Clivus

15 Optic canal

16 Tuberculum sellae

17 Foramen rotundum (right side)

18 Hypophysial fossa (sella turcica)

19 Dorsum sellae

20 Carotid sulcus

21 Spheno-occipital synchondrosis

22 Lateral pterygoid plate

23 Greater wing of sphenoidal bone (orbital surface)

24 Greater wing of sphenoidal bone (maxillary surface)

25 Foramen rotundum (left side)

26 Superior orbital fissure

27 Infratemporal crest of the greater wing

Part of the disarticulated base of the skull.

Ethmoidal, sphenoidal, and occipital bones (from above).

Green = sphenoidal bone; yellow = ethmoidal bone.

Ethmoidal bone (lateral aspect), posterior portion to the right. Ethmoidal bone (anterior aspect).

39

3

2

6

50

51

52

41

42

53

55

43

Disarticulated Skull II: Ethmoidal and Palatine Bones

Occipital bone

28 Jugular tubercle

29 Jugular process

30 Mastoid margin

31 Posterior cranial fossa

32 Lambdoid margin

33 Intrajugular process

34 Condylar canal

35 Lateral part of occipital bone

36 Hypoglossal canal

37 Foramen magnum

38 Internal occipital crest

39 Squamous part of occipital bone

40 Internal occipital protuberance

Maxilla

41 Orbital surface

42 Infra-orbital groove

43 Maxillary tuberosity with foramina

44 Frontal process

45 Nasolacrimal groove

46 Infra-orbital margin

47 Anterior nasal spine

48 Zygomatic process

49 Alveolar process

Palatine bone

50 Orbital process

51 Sphenopalatine notch

52 Sphenoidal process

53 Perpendicular plate

54 Horizontal plate

55 Pyramidal process

Disarticulated base of the skull (anterior aspect). Green = sphenoidal bone;

yellow = ethmoidal bone; red = palatine bone.

Right maxilla, ethmoidal, and palatine bone (lateral aspect). Ethmoidal bone (oblique anterior aspect).

(Schematic drawing.)

2

5

6

4

1

3

4

40 Disarticulated Skull II: Palatine Bone and Maxilla

Part of a disarticulated skull base, similar to the preceding figures, but with palatine

bone. Green = sphenoidal bone; yellow = ethmoidal bone; red = palatine bone.

Left palatine bone (medial aspect,

posterior aspect to the left).

Ethmoidal bone

1 Crista galli

2 Orbital plate

3 Middle concha

Palatine bone

4 Horizontal plate of palatine bone

5 Greater palatine canal

6 Pyramidal process

7 Maxillary process

8 Orbital process

9 Sphenopalatine notch

10 Perpendicular plate of palatine bone

11 Conchal crest

12 Nasal crest

13 Sphenoidal process

Sphenoidal bone

14 Greater wing

15 Superior orbital fissure

16 Greater wing (orbital surface)

17 Lesser wing

Occipital bone

18 Squamous part of occipital bone

Maxilla

19 Maxillary tuberosity

20 Frontal process

21 Orbital surface

22 Infra-orbital margin

23 Infra-orbital groove

24 Zygomatic process

25 Alveolar process

Left palatine bone (anterior aspect). Right maxilla and right palatine bone (lateral aspect).

41

13

19

22

17

20

23

21

18

25

15

16

24

1

Disarticulated Skull II: Palatine Bone and Maxilla

Occipital bone

1 Squamous part

Sphenoidal bone

2 Dorsum sellae

3 Superior orbital fissure

4 Lesser wing

5 Greater wing (orbital surface)

6 Lateral pterygoid plate

7 Medial pterygoid plate

Ethmoidal bone

8 Crista galli

9 Ethmoidal air cells

10 Perpendicular plate

11 Orbital plate

Palatine bone

12 Horizontal plate (nasal crest)

Maxilla

13 Frontal process

14 Inferior orbital fissure

15 Infra-orbital groove

16 Orbital surface

17 Infra-orbital foramen

18 Zygomatic process

19 Anterior lacrimal crest

20 Canine fossa

21 Alveolar process with teeth

22 Anterior nasal spine

23 Juga alveolaria (elevations formed by roots of teeth)

24 Lacrimal groove

25 Maxillary tuberosity with alveolar foramina

26 Palatine process of maxilla

Part of a disarticulated skull.

The left maxilla is added to the preceding specimen.

Left maxilla (lateral aspect). Probe = infra-orbital canal. Left maxilla (posterior aspect).

42 Disarticulated Skull II: Palatine Bone and Maxilla

Occipital bone

1 Groove for superior sagittal sinus

2 Internal occipital protuberance

3 Groove for transverse sinus

4 Internal occipital crest

Sphenoidal bone

5 Greater wing (temporal surface)

6 Lateral pterygoid plate

7 Dorsum sellae

8 Lesser wing

9 Superior orbital fissure

10 Greater wing (orbital surface)

Ethmoidal bone

11 Ethmoidal air cells

12 Crista galli

13 Orbital plate

Maxilla

14 Frontal process

15 Inferior orbital fissure

16 Alveolar process with teeth

17 Palatine process

18 Anterior nasal spine

19 Infra-orbital groove

20 Zygomatic process

21 Location of infra-orbital foramen

22 Middle nasal meatus

23 Inferior nasal meatus

24 Maxillary hiatus

(leading to maxillary sinus)

25 Third molar

26 Lacrimal groove

27 Conchal crest

28 Body of maxilla (nasal surface)

29 Nasal crest

30 Incisive canal

Palatine bone

31 Orbital process

32 Sphenopalatine notch

33 Sphenoidal process

34 Perpendicular plate

35 Conchal crest

36 Horizontal plate

37 Pyramidal process

Frontal bone

38 Squamous part

39 Supra-orbital foramen

40 Frontal notch

41 Frontal spine

Inferior nasal concha

42 Inferior nasal concha

with maxillary process

Part of a disarticulated base of skull. The mosaic of the facial

bones [sphenoidal bone (green), ethmoidal bone (yellow), and

palatine bone (red)] is seen from the antero-lateral aspect.

Left maxilla and palatine bone (medial aspect).