Obstetrics

2. FETAL HEAD
 The skull is made up of the base of
skull and the vault or cranium.
The vault is made of occipital bone
posteriorly, the two parietals at the
sides ,and the temporal bones and
frontal bones anteriorly.
These bones at birth are thin,easily
compressible and joined by
membrane.

3. SUTURES
 Sagittal suture
 Frontal suture
 Coronal suture
 Lambdoidal suture

4. Clinical significance
1) Sutures make moulding possible and some amount
of moulding is needed for vaginal delivary.
2) In hydrocephalus, there is sutural seperation,
resulting in .‘islets of bone in a sea of membranes.’
3) Palpation of the sagittal suture during vaginal
examination gives an idea of the degree of internal
rotation.

5. FONTANELLES
 Fontanelles are the membrane-filled spaces at the meeting point of
the sutures.
• ANTERIOR FONTANELLE OR BREGMA
* Meeting point of sagittal,coronal and
frontal sutures .
*Diamond shaped
*Measures 3×2 cm.
*Ossifies by one and a half years.
• POSTERIOR FONTANELLE OR LAMBDA
*Junction of sagittal suture and the two lambdoidal sutures
*Smaller than the anterior fontanelle
*Y shaped
*Closes at 6-8 weeks

7. Clinical significance
1. Palpation of posterior fontanelle during vaginal
examination denotes position of the head.
2. Palpation of the anterior fontanelle will denote the
degree of flexion of the head .
3. After birth ,fontanelle are useful to asses the
condition of the baby .
4. The fontanelles remain membraneous for some time
after birth . This helps to accomadate the marked
growth of the brain.

8. BONY LANDMARKS
o Occiput is the area occupied by the occipital bone and is
behind and below the posterior fontanelle.
o Vertex is the area bounded by the two fontanelles and the
parietal eminences.
o Sinciput or brow is the area bounded by the bregma and
coronal sutures superiorly and inferiorly by the orbital
ridges.
o Glabella is the raised area between the orbital ridges.
o Nasion is the root of the nose.
o Parietal bosses are the two eminences on the side of each
parietal bone.

9. DIAMETERS OF FETAL SKULL
 ANTERO-POSTERIOR DIAMETERS
1)Suboccipit0bregmatic diameter (9.4 cm) extends
from the undersurface of the occipital bone where it meets
the neck,to the centre of the anterior fontanelle or
bregma.It is the diameter that presents when the head is
well flexed and in occipitoanterior position.
2)Occipitofrontal diameter(11 cm) extends from the
external occipital protruberance to the glabella and
presents when the head is deflexed as in occipitoposterior.
3)Suboccipito frontal(10.5 cm) is another presenting
diameter in occipitoposterior.

11. 4) Verticomental (13.5 cm) extends from the vertex to
the chin and It is the longest antroposterior diameter
of the head and the diameter in which brow presents.
5) Submentobregmatic (9.4 cm) extends from the
junction of the neck and lower jaw to the centre of the
anterior fontanelle and is the diameter in face
presentation.

12. TRANSVERSE DIAMETERS
1) Biparietal(9.4 cm) is the largest transverse diameter
in all cephalic presentations. The head is said to be
engaged when the biparietal diameter has passed
through the pelvic brim. It extends between the two
parietal bosses.
2) Bitemporal diameter(8 cm) is the shortest
transverse diameter and is between the two
temporals.
3) Supersubparietal(8.5 cm) extends from a point
below one parietal eminence to another placed above
the opposite parietal eminence.

14. RELATIONSHIP BETWEEN THE
FOETUS AND PELVIS
1) LIE; relationship between the long axis of fetal ovoid
to the long axis of uterine ovoid.

15. PRESENTATION;part of the fetus that lies over the
pelvic inlet and ccupies the lower pole of uterus.

16. PRESENTING PART; dependent part of the fetus which
is felt first on vaginal examination.
ATTITUDE;relation of the fetal parts to each other.
The main attittudes are flexion and extension.

17. DENOMINATOR ;arbitrarily chosen point on the
presenting part of the fetus, which is used to describe
the position.
POSITION ;relationship of the denominator to the four
quadrants of maternal pelvis.