THE FETAL SKULL.pptx

Fetal skull

1. THE FETAL SKULL

2. Introduction T he skeleton of fetal head. The most important part of fetus 95 % - 96% of baby’s presents with head first It contains the brain

3. It is large compared to the true pelvis Most difficult part to deliver Needs to understand adaptation via birth canal

4. Composition of fetal skull F etal skull consists of: The Vault Base Face

5. The vault T he large dome shaped compressible part ossifies after birth E xtends from orbital region to occipital protuberance to foramen magnum behind. C overs the brain

6. The vault There are five (5) main bones forming the vault. Two frontal bones Two parietal bones One occipital bones

7. The bones of the vault

8. The frontal bones Two frontal bones The right and left frontal bones Lies at the anterior aspect Centre of o ssification-Frontal eminences or frontal bosses .

9. The parietal bones Two parietal bones Lateral on right and left O ssification centre -P arietal eminences .

10. The O ccipital bone L ies posteriorly O ssification centre- occipital protuberance.

11. Sutures Sutures are cranial joints Frontal sutures Sagittal sutures Coronal sutures Lambdoidal sutures

12. Sutures Frontal sutures- B etween the frontal bones. Sagittal sutures - B etween two parietal bones. Coronal sutures - Between the frontal bones and the parietal bones passing from one tempo to the other.

13. Lambdoidal sutures-Between occipital bones and the parietal bones posteriorly.

14. Fontanelles The joining of two or more sutures Two important Fontanelles namely: Anterior fontanelle Posterior fontanelle

15. Anterior Fontanelle (Bregma) It is the largest fontanelle Has a diamond shape F ormed by two coronal sutures, one sagittal suture and one frontal suture.

16. Anterior Fontanelle (Bregma) M easures 3-4cm long and 1.5-2cm wide. C erebral vessels pulsation felt. It closes at 18months of the life .

17. Posterior Fontanelle (lambda) F ormed by occipital bone and two parietal bones T riangular in shape. J unctions- sagittal suture and two Lambdoidal sutures. C loses at 6 weeks

18. Areas on fetal skull Bregma - A nterior fontanelle Lambda- Posterior fontanelle. Verte x - A rea bounded by the anterior and posterior fontanelle and the parietal eminences.

19. It is the highest point on fetal skull About 95% of babies born with head first present by vertex.

20. Areas on fetal skull

21. Areas on fetal skull Glabella - Bridge of nose S inciput /Brow - A nterior fontanelle and the coronal suture to the orbital ridges/bridge of nose .

22. The face – The orbital ridges and the root of the nose to the junction of the chin and the neck. Mentum - The chin

23. Areas on fetal skull The occiput - agn um to posterior fontanelle . Foramen m The occipital protuberance -P rominent point at the posterior aspect of skull . Suboccipital region –below the occipital protuberance  

24. Diameters of fetal skull Two diameters are namely : L ongitudinal diameter Transverse diameter

25. Transverse diameters Bi-Parietal diameter Measured between two parietal eminences (9.5cm )

26. Bi-temporal diameter Measured between farthest point of the coronal sutures at temples 8.2cm) diameter

27. Diameters of fetal skull

28. Longitudinal diameters Sub- occipito -bregmatic (SOB) Below the occiput to center of anterior fontanelle. Measures 9.5cm Sub-occipitofrontal (SOF) Measured from sub occipital region to the center of forehead. It measures 10cm

29. Diameters of fetal skull Occipitofrontal (OF) Measured from center of forehead to occipital protuberance Measures 11.5cm

30. Diameters of fetal skull Mento-vertical (MV) Taken from the chin to the highest point on the vertex. Measures 13.5cm

31. Diameters of fetal skull Sub-mento-vertical (SMV) 11.5cm Measured from the junction of the neck with chin to the highest point on the vertex. It presents in face presentation The head is fully extended.

32. Diameters of fetal skull Sub-mento-bregmatic (SMB) Measured from the junction of chin with the neck to the center of anterior fontanelle. It measures 9.5cm  

33. Presenting diameters These are diameters at right angles to the curve of C arus .

34. Vertex presentation Sub- occipito -bregmatic and the biparietal diameter presents. W ell flexed head Both diameters measures 9.5cm C ircular area makes most favorable shape for dilating cervix.

35. Presenting diameters Sub- occipitofrontal and the biparietal diameter Partially flexed head Good uterine contractions flexes head Labour become normal

36. Presenting diameters O ccipito - frontal (11.5) diameter Erect head V agina walls is distended Labour p rolongs

37. Presenting diameters M entovertical diameter (3.5cm) and bitemporal diameter of 8.2cm present Brow presents Head is partially extended Vaginal delivery is impossible

38. Presenting diameters Submentobregmatic 9.5cm and bitemporal ( 8.2cm) Face presentation H ead is completely extended Small diameter but labour more difficult F acial bones are firmly united and cannot override the irregular bones

39. Moulding T he change in shape of fetal head through the birth canal. Molding is possible as s utures allows slight degree of bending and overriding

40. Moulding Molding is likely to cause brain compression when : E xcessive Too rapid U nfavorable direction.

41. Moulding Excessive moulding Disproportion between pelvis and fetal head I n prolong labour P reterm Post term

42. Moulding Upward moulding F alx cerebri tears and blood vessels rupture leading to intracranial haemorrhage P ersistent occipito posterior position After coming head of breech

43. Moulding Rapid moulding P recipitate labour - There rapid compression and depression leading to tearing and bleeding.

44. Babies who are subjected to severe molding will suffer some degree of asphyxia at birth.