Page 31 - 33Elctronic Book (3) Normal Labor

Anterior &Posterior Fontanelles are important to diagnose:

1-Vertex presentation
2-Position of occiput
3-Degree of flexion of the head
Vertex:

It is the area of the vault of the skull between the anterior and posterior fontanelles
and the parietal eminences.
Anteriorly----- by anterior fontanelle & coronal suture.

Posteriorly---- by posterior fontanelle & lamboidal suture.
Brow:
It is an area bounded on one side by the anterior fontanelle and coronal sutures and on

the other side by the root of the nose and supra-orbital ridges of either side.
Face:
is the area from the junction of the chin and neck to the root of the nose.

Diameters of the Fetal Head

A) Transverse Diameters:
1 Biparietal (9.5 cm); between the two parietal eminences.

2 Subparietal-supraparietal (9 cm), from below one parietal eminence to above
the other. It is 0.5 cm less than the biparietal diameter.
3 Bitemporal (8 cm), between the anterior ends of temporal sutures.

4 Bimastoid (7.5 cm), between the tips of the mastoid processes.
B) Longitudinal Diameters or Engaging Diameters
The engaging diameter is the longitudinal diameter of the presenting part.

1-The suboccipito-bregmatic diameter (9.5 cm).
measured from the suboccipital point, i.e. the junction of the head and neck
posteriorly to the center of the anterior fontanelle. It is the diameter of engagement
in occipito-anterior position when the head is completely flexed.

2. The suboccipito-frontal diameter (10 cm).
Measured from the suboccipital point to the anterior end of anterior fontanelle.

It is the diameter of engagement in occipito-anterior position when the head is not
completely flexed.
3.The occipito-frontal diameter (11.5 cm).
measured from the occipital protuberance to the root of the nose.

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