The document discusses the fetal skull, including its parts, sutures, fontanelles, regions, landmarks, and diameters. The fetal skull is made of thin, pliable bones that allow the head to mold during birth. It has three main parts: the vault, face, and base. Sutures between the skull bones permit gliding movement during molding. Fontanelles are gaps in the sutures that also aid molding. The normal presenting diameter for birth is the suboccipitobregmatic longitudinal diameter of 9.5 cm.

1. FETALSKULL
By
R. KAVITHA
OBG department
Krupanidhi CON

2. INTRODUCTION
The fetal head is large in relation to the fetal body
compared with adult.
Adaptation between the skull and the pelvis is necessary
to allow the head to pass through the pelvis during labour
without complication.

4. FETALSKULL
• The skull bones encases and protect the brain.
• Fetal skull is compressible, and made mainly of thin
pliable tabular(flat) bones forming the vault.
• The fetal skull has three major parts :
• Vault of the cranium (Roof)
• Face
• Base

6. Vault
Is the large, dome shaped part above an imaginary line drawn
between the orbital ridges and the nape of the neck.
Base
The base comprises bones that are firmly united to protect the
vital centers in the medulla oblongata.
Face
Is composed of 14 small bones that are firmly united and non-
compressible.

9. 2 frontal bones
• Forms the forehead or sinciput
• The ossification center of each bone is the frontal
eminance
• The frontal bones fuse into a single bone by 8 years
of age.

10. 2 parietal bone
• Which lie on either side of the skull and occupy most
of the skull
• The ossification center of each of these bones are
called the parietal eminance.

11. 1 occipital bone
• Which forms the back of the skull and part of its
base
• Part of it contributes to the base of the skull as it
contains the foramen magnum, which protects the
spinal cord as it eaves the skull.
• The ossification center is the occipital protuberance.

12. 2 temporal bone
• On both sides of the head
• Forms part of the vault

14. VERTEX
It is a quadrangular area bounded anteriorly by the bregma
and coronal suture behind by the lambda and lambdoidal
sutures and laterally by lines passing through the parietal
eminences.
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.

15. FACE
It is the area bounded by the root of the nose and supra-
orbital ridges and on the other, by the junction of the floor of
the mouth with neck.

16. SINCIPUT
Extends from the anterior fontanelle and the coronal
suture to the orbital ridges.
OCCIPUT
It lies between the foramen magnum and the posterior
fontanelle. The parts below the occipital protuberance is
known as the sub-occipital region.

17. Sutures
• Are spaces between the bones of the skull
• Two or more sutures meet, a fontanelle
• These sutures and fontenlle allow for moulding of
the fetal head during labour.

19. SUTURES
Flat bones of the vault are united together by the non-
osssified membranes attached to the margins of the
bones. These are called sutures.
THE SAGGITALSUTURE:
Lies b/w two parietal bones.
THE CORONAL SUTURES :
Run b/w parietal and frontal bones on either sides.

20. THE FRONTAL SUTURE :
Lies b/w two frontal bones.
THE LAMBDOIDAL SUTURES :
Separate the occiput bone and two parietal bones.

21. IMPORTANCE OF SUTURES
 It permits gliding movement of one bone over the other
during moulding of the head.
 Digital palpations of sagittal suture during internal
examination in labour gives an idea of the manner of
engagement of the head, degree of internal rotation of the
head and degree of moulding of the head.

22. Wide gap in the suture line is called fontanelle.
ANTERIOR FONTANELLE:
Formed by joining four sutures in midplane.
Anteriorly frontal bone-.
Posteriorly saggital.
On either side coronal suture.
Diamond like shape.
Floor is made by a membrane.
Measure about 4cm x 2.5cm.
Ossified at 18months after birth.
FONTANELLES

23. IMPORTANCE OF FONTANELLE
• Its palpation through internal examination denotes the
degree of flexion of the head.
• It facilitates moulding 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 first year of life.
• Palpation of the floor reflects intracranial status-
depressed in dehydration, elevated in raised intracranial
tension.
• Collection of blood and exchange transfusion, on rare
occasion, can be performed through it via the superior
longitudinal sinus.
• Cerebrospinal fluid can be drawn, although rare, through
the lateral angle of the anterior fontanelle from the lateral
ventricle.

25. POSTERIOR FONTANELLE:
Formed by junction of three sutures.
Saggital suture anteriorly.
Lambdoidal suture on either side.

26. Triangular in shape.
Measure about 1.2 x1.2cm.
Its floor is membranous but become bony at 3months.
SAGGITALFONTANELLE:-
 It is inconsistent in its presence. It is situated on the
saggital suture at the junction of anterior to two-third
and posterior one-third.
 It has got no clinical importance.

27. LANDMARKS
• Occiput- is the occipital bone/external occipital protuberance.
• Sinciput- is the forehead region of fetal head.
• Parietal eminences- are the eminences of parietal on either
side.
• Mentum- it is the chin.
• Vertical point- it is the center of saggital suture.
• Frontal point- is the root of nose.
• Sub occiput- is the junction fetal neck and occiput.
• Sub mentum- it is the junction between neck and chin.
• Bi parietal- is the transverse distance between two parietal
eminences.
• Bi temporal- is the distance between two lower end of coronal
suture.

29. DIAMETER OFSKULL
TRANSVERSE DIAMETER:-
• Bi parietal Diameter-
Measure about 9.5cm.
It extends between two parietal eminences.
• Bi-temporal diameter-
Measure about 8.2cm.
It is the distance between anterio-inferior ends of the
coronal suture.
• Bi-Mastoid diameter:
 Measures about 7.5 cm
 It is the distance between either side of the sub-mentum.
• Subparital diameter:
 Measures about 9cm
 Above the parietal eminance to below the opposite eminence.

31. LONGITUIDNALDIAMETER
• Sub-occipitobregmatic- 9.5cm. The diameter from
below the occipital protuberance to the center of the
anterior fontanelle.
• Sub-occipitofrontal- 10cm. The diameter from below the
occipital protuberance to the center of the frontal suture.
• Occipitofrontal-11.5cm. The diameter from the occipital
protuberance to the glabella.

32. Continued…..
• Mentovertical-13.5cm. The diameter from the point of
the chin to the highest point on the vertex, slightly nearer
to the posterior than to the anterior fontanelle.
• Submentovertical-11.5cm. the diameter from the point
where the chin joins the neck to the highest point where
the chin joins the neck to the highest point on the vertex.
• Submentobregmatic-9.5cm. The diameter from the point
where the chin joins the neck to the center of bregma.

34. Presenting diameters
The normal presentation is cephalic - i.e. head down
and occiput anterior - i.e. face downwards. It is this
presentation that gives the best fit, presenting the
smallest diameter to the birth canal.
In normal (flexed) presentation the presenting
diameter is longitudinal suboccipito-bregmatic,
measuring on average 9.5 cm and transvers bi-
parietal diameter 9.5.
Which gives nearly round in shape.

36. SUMMERIZATION
Today we discussed about the Fetal skull:-
• Definition
• Parts of the fetal skull
• Sutures
• Fontanelle
• Region and landmarks of the fetal skull.
• Diameters of Fetal skull

37. BIBLIOGRAPHY
Shirish S Sheth,“Essential of Obstetrics”, 1st Edition,
Jaypee Brothers Medical Publishers, New Delhi,2004,
page no.: 102 - 104.
Diane M, “Myles textbook for Midwives”, 14th edition,
Elsevier Publisher, London, 2008, page no: 157-160
Dutta D.C, “Textbook of obstetrics” 7thedition Published
By New Central Book Agency, page 86-89