The Skull

1. The Skull

2. There are 22 bones in the human skull. • Divided into two groups, the cranial vault and the face. • The cranial vault contains 8 bones. These directly surround and protect the brain. • The face contains 14 bones. 13 of which form the major structure of the face. • The mandible is 1 bone. • There are three bones found in each inner ear.

3. Cranial bones Frontal (1) Sphenoid (1) Parietal (2) Ethmoid (1) Occipital (1) Temporal (2)

4. Frontal bone • Forms anterior portion of skull. • Upper margin contains supraorbitalforamen. • Also contains two frontal sinuses.

5. Frontal bone

6. Parietal • One on each side of skull behind frontal bone. • Fused together at the midline along sagittalsuture. • Join frontal bone at the coronalsuture.

7. Parietal bone

8. Occipital • Joins the parietal bones along the lambdoidal suture. • Forms the back of the skull and base of the cranium. • Foramenmagnum found on lower surface. • Occipitalcondyles (on either side of foramen magnum articulate with C – 1.

9. Occipital bone

10. Temporal • One on each side of skull. • Joins parietal bone along the squamosalsuture. • Externalacousticmeatus located near inferior margin. • Mandibularfossae articulate with mandibularcondyles.

11. Temporal bone continued • Mastoidprocess and styloidprocess both project from the temporal bone. • The zygomaticprocess projects anteriorly from the temporal bone, and joins the zygomaticbone.

12. Temporal bone

13. Sphenoid bone • Found in the anterior cranium. • Central part and two “wings” extending laterally toward each side of the skull. • Forms base of cranium, sides of the skull and the floor and sides of the orbits. • Central portion contains sellaturcica, where the pituitary gland sits. • Contains sphenoidalsinus.

14. Sphenoid bone

15. Ethmoid bone • In front of sphenoid. • Two sides joined by cribriformplate. • Plate forms roof of nasal cavity. • Perpendicular plate projects down from middle of cribriform plate and forms nasal septum. • Contains curled plates called conchae, superior and middle. • Contains ethmoidalsinuses.

16. Ethmoid bone

17. Facial bones

18. Maxillae • Forms upper jaw. • Compose anterior roof of mouth, floors of orbits and sides and floor of nasal cavity. • Also contain sockets of upper teeth. • Maxillary sinuses. • Palatine processes grow together to form anterior portion of hard palate.

19. Maxillae

20. Palatine bones • L-shaped • Located behind maxillae • Horizontal part forms posterior of hard palate and floor of nasal cavity. • Perpendicular portion forms lateral walls of nasal cavity.

21. Palatine bones

22. Zygomatic bones • Form the prominences of the cheek below and to the sides of the eyes. • Form lateral walls and floors of the orbits. • Has a temporal process extending posteriorly to join zygomatic process of temporal bone. • This form zygomaticarch.

23. Zygomatic bone

24. Lacrimal bones • Thin, scalelike structure located on the medial orbit wall between ethmoid and maxilla.

25. Lacrimal bone

26. Nasal bones • Long and thin. • Lie side by side and are fused at the midline forming the bridge of the nose.

27. Nasal bones

28. Vomer bone • Thin and flat. • Midline of nasal cavity • Joins perpendicular plate (posteriorly) and forms nasal septum.

29. Vomer

30. Inferior nasal conchae • Scroll shaped bones. • Attached to lateral walls of nasal cavity • Support mucous membranes within the nasal cavity.

31. Mandible • Horizontal horse-shoe shaped bone with processes projecting upward at each end. • This projection is divided into the posterior mandibular condyle and anterior coronoid process. • Coronoid process provides attachments for muscles used in chewing. • Alveolar arch contains hollow sockets for lower teeth.

32. Mandible