Skull and Mandible (2).pptx

PPT

1. Skull and Mandible

2. Bones for Identification It consists of a five phase procedure: A general description and confirmation of the human origins of the material. T he estimation and segregation of the minimum number of individuals. The determination of sex. The estimation of age. The estimation of stature.

3. Krongman ranks accuracy of sex determination using P elvis at 95% , skull at 90%, the pelvis & skull at 98% and long bones at 80%.

4. Determination of sex is based on two methodological approaches Morphological (based on Shape ) Adult males and females differ in both general size and shape, and this variation is reflected in the skeletal anatomy. Osteometric (based on bone dimensions) Males longer or larger than females.

5. Age Changes in Craniofacial Bones Neonatal : Edentulous jaws, orbit size relatively large I year : Fusion of midline symphysis of mandible, Metopic sutures of two halves of frontal bone fuse, Lat. Sphenoidal synchondrose fuse. Fontanelles: Post & ant. Lateral fuse by 3 months. Ant. Fontanelle by 1 ½ yr (18 MONTHS). 3 years : Condylar portion of occipital bone fuses with squamous part of petrous temporal bone. 5 years :Condylar position of occipital bone fuses with basiocciput .

6. Sphenooccipital Synchondrosis [between basal part of occipital bone & adj. body of sphenoid] – Major skull cartilage centre, fuses by 18-21 years – most useful skeletal ageing factor.

7. Neonatal skull The metopic suture (arrow ) between the two halves of the frontal bone fuses at about 2-6 year, but there are racial variations.

8. Anterior Fontanellae – 18 months

9. Skull The skull is a bony structure which serves as the general framework for the head. The skull supports the structures of the face and protects the head against injury. The skull can be subdivided into two parts: the cranium and the mandible .

10. The features that indicate sex are : General appearance Supra orbital ridges Orbits Glabella Zygomatic arches Mastoid processes External occipital protuberance Mandible Palate

11. MALE SKULL FEMALE SKULL When compared, the female skull appears smaller and more gracile. The male skull is usually larger and more rugged.

12. Supraorbital ridges

13. ORBITS SQUARISH WITH ROUNDISH MARGINS ROUNDISH WITH SHARP MARGINS MALE FEMALE

14. Male skull is larger, has a more sloping forehead. Female skull is smaller and retains frontal and parietal bossing.

15. Glabella MALE FEMALE Well developed Ill developed

16. Zygomatic arches In females , the zygomatic arch is less pronounced , and tends to not extend posteriorly beyond the external auditory meatus. In males , the zygomatic arch is more pronounced or robust, and tends to extend posteriorly beyond the external auditory meatus. Its wider in males compared to females.

17. Mastoid Processes The mastoid processes are located on the inferior portion of the temporal bone, just posterior to the external auditory meatus. Larger and blunt – Male Smaller and pointed - Female

18. External Occipital Protuberance

19. Skull Male female Forehead Steeper/ sloping Vertical Glabella More pronounced Less pronounced Fronto - nasal junction Distinct angulation Smoothly curved Supra - orbital ridge Prominent Less prominent Orbit Square, lower, relatively smaller, round margins Round, higher, relatively larger, sharp margins Zygomatic arch More pronounced Less pronounced Parietal eminence Small Large Mastoid process Medium to large, round , blunt Small to medium, smooth, pointed Digastric groove More deep Less deep Occipital condyles Large Small Foramen magnum Relatively large and long Relatively small and round Palate Larger, broader, U shape Small , tends more to parabola shape

20. MALE FEMALE

21. Suture Age Metopic suture Obliterates at 2-6 yrs Basilar suture Obliterates at 18-21 yrs Sagittal suture Obliterates at 30-35 yrs Coronal suture Obliterates at 35-40 yrs Lambdoid suture Obliterates at 45-50 yrs Squamous suture Obliterates at 60 yrs Spheno -parietal suture Obliterates at 70 yrs Suture closes little latter in females than in males

22. Racial differences

23. Mandible The mandible together with the maxilla, the largest and strongest bone of the face . It forms the lower jaw and holds the lower teeth in place.

24. MANDIBULAR ANGLE Infancy- 160 – 175 1 – 3years - 150 - 160 6 – 12years - 125 - 140 15-17years - 120 - 130 18-21years - 900-125 30-40years - 950-115 > 40 year - obtuse angle

25. MANDIBULAR CHARACTERISTICS USEFUL IN AGEING

26. Chin (anterior mandible) The male mandible tends to have a “square” shape. The female mandib le tends to have a “pointed chin”.

27. RAMUS (rear of the mandible) Mandible in the male is closer to a right angle than the female. In the female , the ramus is an obtuse angle to the lower jaw bone, i.e., greater than 90 degrees. The ramus in the male is wider and larger. MALE FEMALE

28. PALATE Larger, wider and broader Smaller and narrower MALE FEMALE

29. Mandible Male Female Size Larger and thicker Smaller and thinner Chin Square Rounded Body height at symphysis Greater Smaller Angle of body and ramus Less obtuse, prominent and everted More obtuse, not prominent , not everted Condyles Larger smaller