6.FETAL SKULL AND MATERNAL PELVIS FINAL.pptx

Reproductive health and medicine

1. FETAL SKULL AND MATERNAL PELVIS DR.Anne Ngoiri

2. FETAL SKULL

3. Vertex : It is a quadrangular area bounded anteriorly by the bregma and coronal sutures behind by the lambda and lambdoid sutures and laterally by lines passing through the parietal eminences . Brow : It is an area bounded on one side by the anterior fontanel and coronal sutures and on the other side by the root of the nose and supraorbital ridges of either side . Face : It is an area bounded on one side by root of the nose and supraorbital ridges and on the other, by the junction of the floor of the mouth with neck . Sinciput is the area lying in front of the anterior fontanel and corresponds to the area of brow occiput is limited to the occipital bone.

4. SUTURES: The sagittal or longitudinal suture lies between two parietal bones. The coronal sutures run between parietal and frontal bones on either side. The frontal suture lies between two frontal bones. The lambdoid sutures separate the occipital bone and the two parietal bones .

5. IMPORTANCE OF SUTURES 1) It permits gliding movement of one bone over the other during molding of the head, a phenomenon of significance while the head passes through the pelvis during labor. 2) Digital palpation of sagittal suture during internal examination in labor gives an idea of the manner of engagement of the head , degree of internal rotation of the head and degree of molding of the head.

6. FONTANELS: Wide gap in the suture line is called fontanel. two are of obstetric significance: (1) Anterior fontanel or bregma and (2) Posterior fontanel or lambda. Anterior fontanel It is formed by joining of the four sutures in the midplane . anteriorly frontal, posteriorly sagittal and on either side, coronal. The shape is like a diamond. Its anteroposterior and transverse diameters measure approximately 3 cm each. The floor is formed by a membrane and it becomes ossified 18 months after birth. It becomes pathological, if it fails to ossify even after 24 months.

7. Importance: ANTERIOR FONTANELLE Its palpation through internal examination denotes the degree of flexion of the head. It facilitates molding of the head. As it remains membranous long after birth, it helps in accommodating the marked brain growth; the brain becoming almost double its size during the first year of life. Palpation of the floor reflects intracranial status—depressed in dehydration, elevated in raised intracranial tension.

8. Posterior fontanel It is formed by junction of three suture lines — sagittal suture anteriorly and lambdoid suture on either side. I t is triangular in shape and measures about 1.2 × 1.2 cm . Its floor is membranous but becomes bony at term. Thus, truly its nomenclature as fontanel is misnomer. It denotes the position of the head in relation to maternal pelvis.

9. DIAMETERS OF SKULL

10. MOLDING: It is the alteration of the shape of the fore-coming head while passing through the resistant birth passage during labor Molding disappears within few hours after birth. Grading : There are three gradings . Grade-1—the bones touching but not overlapping, Grade-2—overlapping but easily separated and Grade-3—fixed overlapping.

11. Importance: Slight molding is inevitable and beneficial. It enables the head to pass more easily, through the birth canal. Extreme molding as met in disproportion can cause severe intracranial disturbance in the form of tearing of tentorium cerebelli or subdural hemorrhage. Shape of the molding can be a useful information about the position of the head occupied in the pelvis

12. CAPUT SUCCEDANEUM It is theformation of swelling due to stagnation of fluid in the layers of the scalp beneaththe girdle of contact. The girdle of contact is either bony or the dilating cervix or vulval ring. The swelling is diffuse, boggy and is not limited by the suture line It may be confused with cephalhematoma It disappears spontaneously within 24 hours after birth. Caput usually occurs after rupture of the membranes

13. IMPORTANCE It signifies static position of the head for a long period of time. Location of the caput gives an idea about the position of the head occupied in the pelvis and thedegree of flexion achieved.