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.

SUTURES Sagittal suture

Frontal suture

Coronal suture

Lambdoidal suture

Clinical significance1) 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.

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

Clinical significance1. 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.

BONY LANDMARKSo 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.

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.

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.

TRANSVERSE DIAMETERS1) 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.

RELATIONSHIP BETWEEN THE FOETUS AND PELVIS1) LIE; relationship between the long axis of fetal ovoid

to the long axis of uterine ovoid.

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

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.

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.