FETAL Skull for undergraduate (2023)

Title: FETAL Skull for undergraduate

Fetal Skull
Badeea Seliem Soliman Assistant Prof. of
gynecology and obstetricsZagazig university
Fetal SkullVault Face Base

  • The vault is composed of soft bones separated by
    sutures and fontanelles.

Vault is subdivided into

  • Forehead
  • Vertex
  • Occiput

1) Forehead
From Bregma to root of the nose.
(2) Vertex It is an area of the
vault of skull

  • Bounded
  • Anteriorly
  • anterior fontanelle
  • Posteriorly
  • posterior fontanelle
  • Laterally
  • line passing through
  • parietal eminence

3) Occiput
From posterior fontanelle to the external
occipital Protuberance.
Bones of the vault IS (7 bones) 2 frontal
bones2 parietal bones 2 temporal bones1
occipital bone

  • The bones of the vault are not joined thus
    changes in the shape of the fetal head during
    labor can occur due to moulding

Sutures (number 6)
Spaces between skull bones. Made of un-ossified
membranes which allows movements of cranial bones
to decrease the skull diameters.
Sutures 6 in number

  • - Sagittal suture
  • - Frontal suture
  • - Coronal suture
  • Lambdoidal sutures
  • 2 Temporal sutures

Fontanels Areas where sutures meet
6 in numbers
2 anterior temporal fontanelles at the junction
of temporal and coronal sutures

  • 2 Posterior temporal
  • fontanelles
  • at the junction of
  • temporal lambdoidal
  • sutures

no obstetric importance.
Anterior fontanelle

(Video) The Fetal Skull

  • Posterior fontanelle

obstetric importance.
Posterior fontanelle (Lambda) Anterior fontanelle (Bregma)
Small - Lozenge shaped - Large
Obliterated at FT Obliterated at 1.5y after birth
Formed by meeting of 3 bones Connected to 3 sutures - Formed by meeting of 4 bone - Connected to 4 sutures
Bony floor Soft membranous floor
With moulding of the head, over-riding of surrounding bones one parietal bond-overrides the other and both override the occipital bone With moulding gt no over-riding of bones as they are widely separated from the start
Obstetric importance of ant. post. Fontanelle

  • 1- Diagnosis of vertex presentation
  • 2- Detection of the position of the occiput
    (anterior or posterior or lateral)
  • 3- Detection of the degree of flexion or
    deflexion of the head.


  • Bregma ? Ant fontanelle
  • Brow ? lies between Bregma root of the
  • nose
  • Face ? lies between root of the nose
  • subra orbital ridges and chin
  • Occiput ?boney prominence behind post
  • fontanelle
  • Vertex ?Diamond shaped area between ant post
    fontanelles parietal eminences


  • Frontal suture ? between 2 frontal bones
  • Sagittal suture ? between 2 parietal bones
  • Coronal suture ? between parietal frontal
  • Lambdoid suture ? between parietal occipital
  • Temporal suture ? between inferior margin of
  • the parietal temporal bones


  • Anterior fontanelle ?
  • Diamond shaped space between coronal
    sagittal suture - ossifies at 18 m
  • Posterior fontanelle (lambda) ?
  • Triangle shaped space between sagital
  • suture Lambdoidal suture

Diameters of Fetal Skull
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Longitudinal Diameters (6)
1- Suboccipito bregmatic (9.5 cm)

  • From sub occipital point
  • to center of anterior fontanelle
  • The diameter of engagement
  • in occipito anterior position
  • when head is completely flexed

2- Suboccipito - frontal (10 cm)
From sub occipital point to anterior end of
Bregma. 1- Diameter of engagement in vertex
presentation with
mild deflexion of the head. 2-
Diameter that distends the vulva in occipito
anterior if the head is allowed to extend after
3- Occipito -frontal (11.5 cm)
From the occipital protuberance
to the root of the nose. Importance -
Diameter of engagement in O.P. 2- The diameter
that distends the vulva in face to pubis delivery
with O.P. 3-The diameter that distends the vulva
if the head extends before crowning in O A.
4- Sub mento- bregmatic (9.5 cm)
From the junction of the neck and chin to the
centre of the bregma. Importance It is the
engaging diameter in face presentation with
completely extended head.
5- Sub mento -vertical (11.5 cm)

  • From the junction of the neck and chin to the
    vertical point (a point on the sagittal suture
    midway between the anterior and posterior
  • 1- Diameter of engagement
  • in face presentation with the

    head incompletely extended.

  • 2- Diameter that distends the
  • vulva in face delivery (m.a.).

6- Mento- vertical (13.5-14 cm)

  • From the tip of the chin
  • to the vertical point.
  • Importance
  • It is the diameter facing the pelvic brim in brow
  • It is more than the largest diameter of the
    pelvic brim

Longitudinal Diameters (6)

(Video) Fetal skull

  • Suboccipito bregmatic (9.5 cm)
  • Suboccipito -frontal (10 cm)
  • Occipito -frontal (11.5 cm)
  • Sub mento- bregmatic (9.5 cm
  • Sub mento -vertical (11.5 cm)
  • Mento-vertical (13.5-14 cm)

Q What is the name of diameter number 3 4 5?

Transverse diameters (4)
(1) Biparietal diameter (9.5 cm)Between The 2
parietal eminencesIt is the engaging diameter
with synclitism.
2- Supraparietal -subparietal diameter (9
cm)From above the parietal eminence to below the
opposite eminence.Importance It engages in A.
P. diameter of the inlet in case of asynclitism.
3- Bitemporal ( 8 cm) Between the
anterior ends of the temporal sutures.
Importance It engages in the oblique diameter
in O.P. Position
4- Bimastoid ( 7.5 cm) Between The tips of the
2 mastoid processes.
Transverse diameters of Fetal Skull
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Important Definitions
Fetal Attitude

  • It is the relations of the fetal parts to each
    other, it is in a general flexion attitude i.e.
    all joints are flexed


  • Complete Flexion
  • Most common ( in Vertex
  • Deflexion In O.P position.
  • Military attitude Midway between flexion
  • extension (brow).
  • Complete extension In face presentation.

Lie The relation between the longitudinal axis
of the fetus to that of the mother.
Types 1) Longitudinal (99.5 ).
2-Oblique or transverse (0.5 ).
Presentation It is the lowermost part the fetus
the part related to the pelvic brim and first
felt by vaginal examination.
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N.BIn term pregnancy cephalic presentation is
more common than breech

  • Because of
  • The head is heavier so it occupies the LUS
  • The buttocks are larger so it occupies the fundus

Position The relation of the back of the fetus
to the right or to the left sides of the mother
and whether it is directed anteriorly or

  • 1 st position The back is left and anterior.
  • 2 nd position The back is right and anterior.
  • 3 rd position The back is right and posterior.
  • 4 th position The back is left and posterior

The denominator A landmark on the presenting
part denoting the position

  • Occiput ------------------- in vertex.
  • Frontal bone------------- in brow .
  • Chin ----------------------- in Face.
  • Scapula ------------------- in shoulder
  • Sacrum -------------------- in Breech

Vertex ---------------- occiput
In vertex presentation (the commonest), There
are 8 positions
- Right and left occipito-anterior - Right and
left occipito- posterior - Right and left
occipito-transverse - Direct occipito anterior
and posterior
8 positions
Fetal Position
The fetal compass rose
O.A is more common than O.P because

  • The concavity of the front of the fetus
  • (due to its flexion) fits
  • into the convexity of
  • lumbar lordosis of
  • maternal spine.

LOA is more common than ROA and ROP is more
common than LOP because

  • In LOA and ROP the head enters the pelvis in the
    right oblique diameter which is more favorable
    than the left oblique
  • (2) Dextro-rotation of the head favours LOA if
    the back is directed to left side and ROP if the
    back is directed to right side.

Passage of the widest transverse diameter of
the presenting part through the plane of the
pelvic inlet.Example B.P.D. in cephalic
Timing of engagementIn
PG (last 3 4 weeks)In MP it usually occurs
in the 1st stage or with onset of 2nd


  • Detection of engagement
  • Abdominally by 1st pelvic grip (Rule of fifths).
  • Vaginally (Rule of station).

Station The level of the
head in the pelvis.
Abdominally (Rule of fifths).
Detection of engagement
Rule of fifths

  • 0 station 2/5 of the head are felt abdominally
  • above symphysis pubis
  • 1 station 1/5 of the head is felt
  • 2 station none of the fetal head is felt
  • -1 station 3/5 head is felt
  • -2 stations 4/5 head is felt
  • -3 station the whole head (5/5) is felt

Vaginally(Station of the head) The level of the
vertex is assessed in relation to the level of
ischeal spines At this level it is called
station (0) above this level is by minus every 1
cm and below by pulse every 1 cm
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Station of the head

  • 0 The lowest part of the head is felt vaginally
  • the level of the ischial spine.
  • 1 If 1 cm. below the level of ischial spines.
  • 2 If 2 cm below the level of ischial spines.
  • 3 If 3 cm. below the level of ischial spines
  • -1 If 1 cm above the level of ischial spines.
  • -2 If 2 cm above the level of ischial spines.
  • -3 If 3 cm above the level of ischial spines.

Causes of Non-engagement of fetal head
In 20 of cases no cause is found.
Synclitism Asynclitism
Synclitism When the 2 parietal bones are at the
same level
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  • One parietal bone is presented below the other
    due to lateral inclination of the head, the
    sagittal suture lies nearer to the promontory or


  • Value
  • Asynclitism brings the shorter sub parietal -
    Supraparietal (9 cm) to enter the pelvis instead
    of B.P.D. (9.5cm).
  • - Slight degree of asynclitism may occur in
    normal labour

Posterior asynclitism (anterior parietal bone presentation Anterior asynclitism (posterior parietal bone presentation,
The anterior parietal bone is lower and the sagittal suture is nearer to the promontory. - It occurs more in MP due to laxity of the anterior abdominal wall. The posterior parietal bone is lower and the sagittal suture is nearer to the symphysis pubis. It occurs more in PG due to tense abdominal wall.
Anterior parietal bone presentation is more
favorable than posterior parietal bone
presentation because

  • (1) During correction of asynclitism, the head
    meets only the resistance of the sacral
    promontory while in posterior parietal bone
    presentation the head meets the resistance of the
    whole length of symphysis.
  • (2) The head lies more in the pelvic axis with
    anterior parietal bone presentation.
  • (3) With posterior parietal bone presentation
    ------ LUS more liable to stretch and rupture.


  • MCQ

(1) The greatest diameters of the normal fetal
head is which of the following?

  1. Occipito frontal
  2. Suboccpito bregmatic
  3. Bitemporal
  4. Biparital
  5. Mento vertical

(2) The relation of the fetal parts to each other
determines which of the following?

  1. Presentation of the fetus
  2. Lie of the fetus
  3. Attitude of the fetus
  4. Position of the fetus
  5. Intention of the fetus

(3) In vertex presentation, what fetal part
determined the fetal position?

(Video) The Fetal Skull- Full explanation for Practical Exams

  1. Mentum
  2. Sacrum
  3. Acromion
  4. Occiput
  5. Sinciput

(4) The relationship of the long axis of the
fetus to that of the mother called IS

  1. Lie
  2. Presentation
  3. Attitude
  4. Posture
  5. Position

(5) Regarding the fetal skull fontanelles, one
of the following is true

  • There are 3 fontanelles
  • The posterior fontanelle is closed at 28 weeks of
  • The anterior fontanelle is closed at birth
  • The anterior fontanelle is irregular in shape
  • The posterior fontanelle is triangular in shape

(6) The incorrect statement regarding fetal

  1. It is the part of the fetus that enters the
    maternal pelvis first.
  2. It is always cephalic
  3. In cephalic presentation, it is more common to be
  4. In face presentation the head is completely
  5. The denominator is always the lowest part of the
    presenting area

( E )
(7) The correct statement for anterior fontanelle
(Bregma) is

  • Triangular in shape
  • Smaller than the posterior fontanelle
  • Has bony floor
  • Becomes obliterated 18 months after birth

( D )
(8) The correct statement for biparietal diameter
of fetal head

  1. Extend from a point below one parietal bone to a
    point above the opposite eminence
  2. It is the engaging diameter in brow presentation
  3. It is 9.5 cm in length
  4. All of the above

( c )
(9) Concerning the occipto frontal diameter, all
of the following are true EXCEPT

  1. It extends from occipital protuberance to root of
    the nose
  2. It is 9.5 cm I length
  3. It is the diameter of engagement in after coming
    head of breech.
  4. It is the diameter distending the vulva in face
    to pubis delivery

( B )
(10) As regards the mento vertical diameter, all
of the following are true EXCEPT

  1. It is 13.75 cm in length
  2. It is the diameter of engagement in face
  3. It extends from tip of chin to the verticle point
  4. It is larger than the largest diameter of pelvic

( B )
(11) The shortest diameter of the pelvic cavity

  1. The external conjugate
  2. Diagonal conjugate
  3. The bispinous
  4. The true conjugate
  5. The transverse

( C )
Short questions
What are the various types of fetal

(Video) Palpation of the bones of the skull, fontanels and cranial sutures 1

  • What are the different cephalic presentations?

How is position determined?
What is the definition of mal presentation?

  • What is the Rule of fifths?

Causes of non engagement ?
Definition of

  1. Lie
  2. Vertex
  3. Attitude
  4. Engagement
  5. Pelvic brim
  6. Synclitism
  7. Asynclitism
  8. Station of the head

Thank you


What is the clinical significance of fetal skull? ›

Two key functions of the fetal skull are the protection of the brain, which is subjected to pressure as it descends through the birth canal during labour, and an ability to change shape, adapting to the process of labour in response to uterine contractions and the size and shape of the pelvis.

What is the price of fetal skull model? ›

Human Fetal Skull For Bones & Skeleton Model at Rs 1590 | Karol Bagh | New Delhi | ID: 2895009430.

What is the objective of fetal skull? ›

1 Fetal skull bones. The skull bones encase and protect the brain, which is very delicate and subjected to pressure when the fetal head passes down the birth canal.

What is the significance of fetal skull diameter? ›

It contains the delicate brain and about 95% of babies present by head. Sound knowledge of fetal diameter and measurement cause least problems during labour and delivery through diagnosis of abnormalities presentation and position, also disproportion between the fetal head and the pelvis can be easily recognized.

How are babies skulls different from adults and why? ›

At birth the facial portion of the head is smaller than the cranium having a face-to-cranium ratio of 1:8 (cf. adult ratio of 1:2.5). Relative to the facial profile, the newborn forehead is high and quite bulged, due to the massive size of the frontal lobe of the brain (Fig. 6).

Why is the skull the most important? ›

Protection to the brain (cerebellum, cerebrum, brainstem) and orbits of the eyes. Structurally it provides an anchor for tendinous and muscular attachments of the muscles of the scalp and face. The skull also protects various nerves and vessels that feed and innervate the brain, facial muscles, and skin.

What is the average price for a human skull? ›

A top-of-the-line skull from a young adult will set you back $1,500 or more. Skulls from young adults are especially costly. They're preferred because bones get thinner and more fragile as we age. A skull from a teenager for sale from the website for The Bone Room in Berkeley, Calif., sold recently for $3,500.

How much is a bone skull? ›

The skull is made up of 22 bones as well as a plethora of cartilage and ligaments.

How many fetal skulls are there? ›

An infant's skull is made up of 6 separate cranial (skull) bones: Frontal bone.

What are the three main parts of the fetal skull? ›

Anatomy of the Newborn Skull
  • 2 frontal bones.
  • 2 parietal bones.
  • 1 occipital bone.

What is fetal skull in nursing? ›

It consists of vault, face and base. The vault is composed of: 2 frontal bones separated by the frontal suture, 2 parietal bones separated by the sagittal suture, the occipital bone separated by the lambdoidal suture from the parietal bones, while the coronal suture separates the frontal from the parietal bones.

What features characterize the fetal skull? ›

The fetal skull contains cranial bones that have not yet joined together. The spaces that lie between the large cranial bones (the frontal bone, the parietal bone, the temporal bone and the occipital bone) are the membrane-bound fontanelle. This is why new borns have a "soft spot" on their head.

What is the most important fetal measurement? ›

Fetal biometry, with the help of ultrasonography (USG) provides the most reliable and important information about fetal growth and well-being. Frequently used parameters for fetal measurements by this method are the biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL).

What is the normal diameter of fetal skull? ›

The suboccipitobregmatic diameter (9.5 cm) extends from the under surface of the occipital bone, where it meets the neck, to the center of bregma is the engaging diameter in vertex presentation. The circumference of the fetal head at this plane is 27.5 cm.

Which diameters of the fetal skull are important for engagement? ›

Engagement of the fetal head is considered to have occurred when the biparietal diameter (BPD), the largest transverse diameter of the fetal head, has traversed the pelvic inlet1, 2.

How does the skull change from birth to adulthood? ›

At birth, the cranial bones are linked together with soft fibers, and at about one year of age, the fibers in the skull disappear as the cranial bones begin to fuse together. It's also common for gaps (commonly known as “soft spots”) to form as protective tissue fades away and hard bone forms.

Are babies skulls stronger than adults? ›

Scientists from the University of Pennsylvania have determined that the young skull is only an eighth as strong as an adult one. They also found that the skulls are far more easily deformed by blows to the head, making the babies' brains more vulnerable to injury.

How does skull shape change with age? ›

But using CT scans of 100 men and women, the researchers discovered that the bones in the human skull continue to grow as people age. The forehead moves forward while the cheek bones move backward. As the bones move, the overlying muscle and skin also move, subtly changing the shape of the face.

What is the weakest point in the human skull? ›

The pterion is a craniometric point at the point where the greater wing of the sphenoid bone, the parietal bone and the frontal bone meet. It is the weakest point of the skull. The middle meningeal artery is located underneath it on the internal surface of the skull.

Who has the strongest skull in the world? ›

John Ferraro is the Hammerhead. His skull is more than two times thicker than the average human's, and he uses it to hammer nails into wood, snap baseball bats in half, and bend steel bars!

What are the 3 main functions of the skull? ›

In humans these sensory structures are part of the facial skeleton. Functions of the skull include protection of the brain, fixing the distance between the eyes to allow stereoscopic vision, and fixing the position of the ears to enable sound localisation of the direction and distance of sounds.

What states is it illegal to own a human skull? ›

Louisiana, Georgia, and Tennessee are the only states to have restrictions. So yes, it is completely legal to buy human bones in the US as long as you don't live in those three states! For this reason, we do not ship human remains to these three states, or internationally.

Can you sell human remains on eBay? ›

Human body parts or items containing body parts are not allowed. We don't allow the sale of human bodies, body parts, or products made from the human body on eBay.

How much is a bounty skull? ›

Villainous Bounty Skull
CompanyOrder of Souls
Sell toMadames or The Servant of the Flame
Base Gold Reward750 - 1450
Emissary Value3240
4 more rows

Are human skulls expensive? ›

But if you're looking for a skull, be forewarned: they're not cheap. A top-of-the-line skull from a young adult will set you back $1,500 or more. Skulls from young adults are especially costly. They're preferred because bones get thinner and more fragile as we age.

Which is the strongest bone in our human body? ›

The femur is one of the most well-described bones of the human skeleton in fields ranging from clinical anatomy to forensic medicine. Because it is the longest and strongest bone in the human body, and thus, one of the most well-preserved in skeletal remains, it makes the greatest contribution to archaeology.

What is a human skull called? ›

The human cranium, the part that contains the brain, is globular and relatively large in comparison with the face. In most other animals the facial portion of the skull, including the upper teeth and the nose, is larger than the cranium.

Do male and female skulls look different? ›

Generally, male skulls are heavier, the bone is thicker and the areas of muscle attachment are more defined than in females. There are also key differences in the appearance of the forehead, eyes and jaw between men and women, that are used to determine the sex of a skull.

How many skull bones do newborns have compared to adults? ›

How many bones does a newborn human baby have versus an adult? A human baby is born with 176 true bones, but its skull is actually three bones that have not yet fused. (This is a nice feature since it allows for easier delivery when the baby is born.) As a baby grows, the three bones fuse into one.

What shape is fetal skull? ›

The fetal head is egg-shaped, being broader posteriorly and symmetric without irregularity of contour. Ossification of the skull vault is complete by 12 weeks' gestation with the sutures remaining visible throughout pregnancy.

What is fetal skull made of? ›

Only a comparatively small part of the head at term is represented by the face. The rest of the head is composed of the firm skull, which is made up of two frontal, two parietal, and two temporal bones, along with the upper portion of the occipital bone and the wings of the sphenoid.

What are the 4 major structures of the skull? ›

There are four major sutures that connect the bones of the cranium together: the frontal or coronal, the sagittal, the lambdoid, and the squamous.

Why is the fetal skull different? ›

Differences between a fetal skull and an adult skull include: The fetal skull bones are not joined by sutures. The relative size of the fetal facial bones compared to the cranial bones are smaller in the fetal skull than for the adult. The adult has one frontal bone, the fetus frontal bone is in two halves.

How does the nurse assess fetal position? ›

It can be assessed through vaginal examination, abdominal inspection and palpation, sonography, or auscultation of fetal heart tones. By knowing the fetal presentation, you can anticipate which part of the fetus will first pass through the cervix during delivery.

What is a fetal assessment? ›

An ultrasound scan is often done at 18 to 23 weeks of your pregnancy. This test lets us see how your baby is growing and developing as well as confirm an estimated due date.

What is the importance of knowledge of bony pelvis and fetal skull to a midwife? ›

In order to monitor maternal and fetal wellbeing and promote progress in labour, the midwife needs a thorough understanding of: the maternal pelvis, the external structure of the fetal skull, and how the presentation and attitude of the fetus determines the presenting diameter of the skull.

What is unique to the newborn skull? ›

Fontanelles are the soft spots on an infant's head where the bony plates that make up the skull have not yet come together. It is normal for infants to have these soft spots, which can be seen and felt on the top and back of the head. Fontanelles that are abnormally large may indicate a medical condition.

What structures are unique to fetal skull? ›

Which structures are unique to the fetal skull and provide additional space for molding the head shape as the baby passes through the birth canal? hyoid.

What are the two main features of skull? ›

The adult human skull consists of two regions of different embryological origins: the neurocranium and the viscerocranium. The neurocranium is a protective shell surrounding the brain and brain stem. The viscerocranium (or facial skeleton) is formed by the bones supporting the face.

How accurate are fetal head measurements? ›

Conclusion. The ultrasound estimation of fetal head circumference is associated with significant underestimation of the actual head circumference measured postnatally. The error in measuring fetal HC increases with advanced gestational age, low liquor, and anterior location of the placenta.

What is the most important week of fetal development? ›

First Trimester (0 to 13 Weeks)

The first trimester is the most crucial to your baby's development. During this period, your baby's body structure and organ systems develop. Most miscarriages and birth defects occur during this period. Your body also undergoes major changes during the first trimester.

Can ultrasound head measurements be wrong? ›

Overall, sonographic HC measurements consistently underestimated actual HC measured postnatally (mean simple error, - 13.6 mm; 95% CI, - 13.2 to - 13.9), and the difference increased with gestational age.

Why is fetal skull important? ›

Two key functions of the fetal skull are the protection of the brain, which is subjected to pressure as it descends through the birth canal during labour, and an ability to change shape, adapting to the process of labour in response to uterine contractions and the size and shape of the pelvis.

How do you measure fetal head descent? ›

Fetal head descent was quantified by measuring the angle between a line placed through the midline of the pubic symphysis along the pubic ramus and a line running from the inferior apex of the symphysis tangentially to the most anterior part of the fetal skull.

Can fetal head measurements be wrong? ›

The errors in individual fetal measurements and estimated fetal weight (EFW) have been well documented. For example, 95% confidence intervals (95% CI) for abdominal circumference (AC), head circumference (HC) and femur length (FL) of ±9%, ±5% and ±11%, respectively, and for EFW of up to ±50% have been reported.

What does 3 5 engaged mean? ›

Baby's head is just beginning to enter into the pelvis, but only the very top or back of the head can be felt by your doctor or midwife. 3/5. At this point, the widest part of your baby's head has moved into the pelvic brim, and your baby is considered engaged.

Which fetal skull bone is very significant during labor? ›

The suboccipito-bregmatic diameter (SOBD) was more sensitive to the changes of labor force than other fetal skull diameters.

What does 3 5 palpable mean? ›

3/5 of the head palpable means that the head cannot be lifted out of the pelvis. On doing a deep pelvic grip, your fingers will move outwards from the neck of the fetus, then inwards before reaching the pelvic brim.

What is the clinical significance of fontanelles? ›

Fontanelles are essential for the proper development of the baby's brain as they are held together by the flexible sutures which protect the brain from the head impacts. Also the skull bones or cranium grows along with the brain. This happens as the suture lines increase.

What is a fontanelle and why is it important for normal skull development? ›

In an infant, the space where 2 sutures join forms a membrane-covered "soft spot" called a fontanelle (fontanel). The fontanelles allow for growth of the brain and skull during an infant's first year. There are normally several fontanelles on a newborn's skull.

What are the abnormalities of the fetal skull? ›

There are many types of birth defects that can cause abnormalities in the skull. Three of the most common are anencephaly, craniosynostosis, and encephalocele. What causes skull deformities? Skull deformities can be caused by conditions that occur before birth, such as anencephaly, craniosynostosis, and encephalocele.

Can adults have fontanelles? ›

Anterior Fontanelle

The position of this largest soft spot can be easily seen on a newborn; in adults, the location of the now-fused fontanelle is at the junction of the frontal, coronal, and sagittal sutures of the skull.

What happens to fontanelles in adulthood? ›

They stay connected throughout adulthood. Two fontanelles usually are present on a newborn's skull: On the top of the middle head, just forward of center (anterior fontanelle) In the back of the middle of the head (posterior fontanelle)

At what age does the fontanelle close? ›

These soft spots are spaces between the bones of the skull where bone formation isn't complete. This allows the skull to be molded during birth. The smaller spot at the back usually closes by age 2 to 3 months. The larger spot toward the front often closes around age 18 months.

At what age does the skull fuse? ›

Around two years of age, a child's skull bones begin to join together because the sutures become bone. When this occurs, the suture is said to “close.” In a baby with craniosynostosis, one or more of the sutures closes too early.

Which two fontanelles are clinically important? ›

They may present the sagittal Fontanelle and/or the metopic Fontanelle; The presence of sagittal Fontanelle is clinical associated to Down's Syndrome and other anomalies.

What are the two most important fontanelle? ›

Fontanelles, often referred to as "soft spots," are one of the most prominent anatomical features of the newborn's skull. Six fontanelles are present during infancy, with the most notable being the anterior and posterior fontanelles.

When should I be concerned about my fetus head size? ›

Technically, your child's head circumference (measurement around the widest part of their head) is greater than the 97th percentile. This means their head is larger than 97% of children of the same age and sex. Macrocephaly can be a sign of a condition that requires treatment.

Does the same skull bone in adults also present in fetal skull? ›

Even though the skull bones of an adult are the same as those found in the fetal skull, a distinctive difference between the two is that the skull bones in the fetal are not fused while the skull bones in an adult skull are fused. In addition, the fetal bones are soft compared to those of an adult skull.

What is the most common fetal malformation? ›

The most common severe congenital disorders are heart defects, neural tube defects and Down syndrome. Although congenital disorders may be the result of one or more genetic, infectious, nutritional or environmental factors, it is often difficult to identify the exact causes. Some congenital disorders can be prevented.

What is the most common fetal brain anomaly? ›

Dandy-Walker malformation is the most common congenital cerebellar malformation, characterized by hypoplasia or agenesis of the cerebellar vermis with associated enlargement of the posterior fossa, dilatation of the fourth ventricle, ventriculomegaly, and communication of the fourth ventricle with the cisterna magna.

What causes skull deformities? ›

Most skull deformities result from abnormal development of the brain or from premature closure of some sutures. Babies born with acrania (absence of calvaria) fail to survive because most of the brain is absent. In microcephaly, the size of the brain is very small, and consequently the skull fails to grow.


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