FETAL SKULL | Bones | Sutures | Diameters | Fontanels | Anatomy | OBG Lecture | The Nurses Station

Summary

This video discusses the anatomy of the fetal skull, focusing on its bones, regions, sutures, fontanels, and diameters. It explains the skull's significance during childbirth, highlighting how its bony structure can pose challenges while also being somewhat compressible. The video details the various areas of the skull, including the vertex, face, occiput, and base, as well as the key sutures and fontanels. Finally, it covers the different diameters of the skull, which play crucial roles in the birthing process depending on the baby's head position.

Takeaways

• 💡 The fetal skull is larger in proportion to the body and is the most challenging part to pass through the mother's pelvis due to its hard bony nature, though it is somewhat compressible.
• 🔍 The skull is divided into zones of obstetrical importance: vertex, face, brow, and occiput, each with specific boundaries and landmarks.
• 🦴 The skull bones include two frontal bones, two parietal bones, one occipital bone, and two temporal bones, each with unique features and functions.
• 🤕 The sutures of the skull are non-fused membranes that allow for the gliding movement of bones during childbirth, a process known as molding.
• 🔗 The obstetrically important sutures include the frontal, sagittal, coronal, lambdoid, and squamosal sutures, which facilitate the molding of the skull during delivery.
• 💠 Fontanels are wide gaps in the suture lines, with the anterior fontanelle (bregma) and posterior fontanelle (lambda) being of particular obstetric importance.
• 💎 The anterior fontanelle is diamond-shaped with approximate diameters of three centimeters, while the posterior fontanelle is triangular and about 1.2 centimeters in size.
• 🧠 The fetal skull's engaging diameter depends on the degree of head flexion, with different diameters engaging in various presentations such as vertex, face, or brow.
• 📏 The suboccipitobregmatic diameter is crucial for complete head flexion in vertex presentation, measuring 9.5 centimeters.
• ⏳ The anterior fontanelle ossifies by 18 months after birth, and failure to do so by 24 months is considered pathological.

Q & A

What is the significance of the fetal skull's shape and size during childbirth?

The fetal skull is larger in proportion to the fetal body and is the most difficult part of the baby to pass through the mother's pelvic canal due to its hard, bony nature. However, it is compressible to some extent, which is crucial during childbirth.

How is the skull divided into zones of obstetrical importance?

The skull is divided into several zones: the vertex, the anterior fontanelle (bregma), the posterior fontanelle (lambda), the occiput, and the base. Each zone has specific boundaries defined by sutures and bony landmarks.

What are the key bones that form the fetal skull?

The key bones include two frontal bones, two parietal bones, one occipital bone, and two temporal bones. Each plays a role in the structure and function of the fetal skull.

What is the role of sutures in the fetal skull during childbirth?

Sutures are the immovable fibrous joints between the bones of the skull. They allow for some degree of compression and gliding of one bone over another, known as molding, which facilitates the passage of the skull through the birth canal.

What are fontanels and why are they important in obstetrics?

Fontanels are wide gaps in the suture lines that allow for the bones of the skull to move and overlap during childbirth. The anterior and posterior fontanels are of particular obstetric importance.

What is the shape and size of the anterior fontanelle?

The anterior fontanelle is diamond-shaped and is formed by the joining of four sutures. Its anteroposterior and transverse diameters measure approximately three centimeters each.

How does the posterior fontanelle differ from the anterior fontanelle in shape and size?

The posterior fontanelle is triangular in shape and is formed by the junction of three suture lines. It measures about 1.2 by 1.2 centimeters, which is smaller than the anterior fontanelle.

What are the different diameters of the fetal skull and their significance during labor?

The fetal skull's diameters include the suboccipitobregmatic, submentovertical, occipitofrontal, mentovertical, and submentovertical. These diameters determine the ease of the fetal head's passage through the birth canal depending on the degree of head flexion and presentation.

What is the suboccipitobregmatic diameter and its measurement?

The suboccipitobregmatic diameter extends from the nape of the neck to the center of the bregma and measures 9.5 centimeters. It is the engaging diameter in case of complete flexion of the head and vertex presentation.

What is the biparietal diameter and its significance in labor?

The biparietal diameter measures 9.5 centimeters and extends between two parietal eminences. It nearly always engages during labor, regardless of the position of the head.

Outlines

00:00

💠 Fetal Skull Anatomy and Obstetric Significance

This paragraph delves into the intricate details of the fetal skull, emphasizing its unique structure and obstetric importance. The skull is described as being disproportionately large relative to the fetal body and poses a significant challenge during childbirth due to its hard, bony composition. However, it retains some degree of compressibility. The skull is divided into distinct zones including the vertex, brow, and occiput, each with specific boundaries and characteristics. The bones of the skull are highlighted, with the frontal bones forming the brow and the parietal bones above, while the occipital bone is at the back. Sutures, which are the fibrous joints between the bones, are crucial for the skull's flexibility during labor, allowing for 'molding.' Fontanelles, the soft spots on the skull, are also discussed, with the anterior and posterior fontanelles being of particular obstetric interest. Lastly, the paragraph covers the various diameters of the fetal skull, which are critical for determining the ease of passage through the birth canal.

05:03

🔍 Detailed Examination of Fetal Skull Diameters

The second paragraph continues the exploration of the fetal skull, focusing on the specific diameters that are essential for understanding the mechanics of labor and delivery. The engaging diameters are detailed, including the suboccipitobregmatic, submentovertical, and the transverse diameters, each with its unique measurement and relevance to different stages and presentations of fetal head during childbirth. The paragraph explains how these diameters are engaged based on the degree of flexion or extension of the fetal head, which is pivotal for a successful vaginal delivery. The biparietal and bitemporal diameters are also mentioned, providing a comprehensive overview of the dimensions that medical professionals consider when assessing the feasibility of a vaginal birth.

Keywords

💡Fetal Skull

The fetal skull is the bony structure of a baby’s head, which is larger in proportion to the fetal body and is one of the most difficult parts of the baby to pass through the mother's pelvic canal during childbirth. The video emphasizes its compressibility and anatomical importance during labor.

💡Sutures

Sutures are non-ossified membranes that connect the bones of the fetal skull, allowing for movement between bones during childbirth, a process known as molding. Key sutures discussed include the frontal, sagittal, coronal, lambdoid, and squamosal sutures, which aid the skull's flexibility in labor.

💡Fontanels

Fontanels are the soft spots on a baby's skull where the bones have not yet fully fused. The video mentions two major fontanels of obstetric importance: the anterior fontanel (bregma) and the posterior fontanel (Lambda), which allow for skull molding during childbirth and later ossify as the child grows.

💡Anterior Fontanel

The anterior fontanel, also known as the bregma, is a diamond-shaped soft spot located at the junction of the frontal and coronal sutures. It plays a critical role during childbirth by allowing the skull to flex and later ossifies by 18-24 months after birth.

💡Posterior Fontanel

The posterior fontanel, or Lambda, is a smaller triangular gap between the sagittal and lambdoid sutures. It is significant in childbirth because its flexibility helps the fetal skull pass through the birth canal. This fontanel typically ossifies shortly after birth.

💡Molding

Molding refers to the process during childbirth in which the bones of the fetal skull slide over one another, facilitated by the sutures and fontanels, to allow the head to fit through the birth canal. This flexibility is crucial for a successful delivery.

💡Engaging Diameter

Engaging diameter is the measurement of the fetal skull's dimensions that interact with the pelvic canal during labor. Depending on the degree of flexion or extension of the fetal head, different diameters like the suboccipitobregmatic or occipitofrontal are engaged, as explained in the video.

💡Suboccipitobregmatic Diameter

This is the smallest engaging diameter of the fetal skull, measuring 9.5 cm, and is involved when the fetal head is fully flexed in vertex presentation. It extends from the nape of the neck to the center of the bregma.

💡Vertex Presentation

Vertex presentation occurs when the top of the fetal head, or vertex, presents first during childbirth. This is the most common and favorable position for delivery, and the video discusses how different skull diameters, like the suboccipitobregmatic, engage in this presentation.

💡Biparietal Diameter

The biparietal diameter is the transverse measurement between the two parietal eminences of the fetal skull, measuring approximately 9.5 cm. It is one of the most important diameters in labor as it nearly always engages regardless of the fetal head position.

Highlights

The fetal skull is larger in proportion to the body and can be challenging to pass through the mother's pelvis.

The skull is compressible to some extent, which is crucial for childbirth.

The skull is divided into zones of obstetrical importance: vertex, face, and occiput.

The vertex is a quadrangular area defined by specific sutures and eminences.

The face area, or since put, is bounded by the anterior fontanelle and the root of the nose.

The occipital region is limited to the occipital bone, which also contributes to the skull's base.

The bones of the skull include two frontal bones, two parietal bones, one occipital bone, and two temporal bones.

Sutures are non-fused membranes that unite the bones of the skull vault.

Obstetrically important sutures include the frontal, sagittal, coronal, lambdoid, and squamosal sutures.

Sutures allow for the gliding movement of bones during childbirth, known as molding.

Fontanels are wide gaps in the suture lines, with the anterior and posterior fontanels being of obstetric importance.

The anterior fontanelle is diamond-shaped and measures approximately three centimeters in diameter.

The posterior fontanelle is triangular and measures about 1.2 by 1.2 centimeters.

The engaging diameter of the fetal skull depends on the degree of head flexion.

Suboccipitobregmatic is the engaging diameter in case of complete head flexion and vertex presentation.

Submentovertical is the engaging diameter when there is partial extension of the fetal head.

Transverse diameters, such as biparietal and bitemporal, are crucial in the mechanism of labor.

Transcripts

foreign

[Music]

we will talk about the fetal skull

its Bones the areas of the skull sutures

fontanels and diameters

fetal skull is all shaped at term it is

larger in proportion to the fetal body

and in comparison with the true pelvis

the fetal skull is the most difficult

part of the baby to pass through the

mother's pelvic Canal due to the hard

bony nature of the skull however it is

compressible to some extent first we

will talk about the areas of skull the

skull is arbitrarily divided into

several zones of obstetrical importance

these are the vertex it is a

quadrangular area bounded anteriorly by

the bregma and coronal sutures behind by

the Lambda and lambdoid sutures and

laterally by the lines passing through

the parietal eminences bro or since put

is an area

bounded on one side by the anterior

fontanelle and coronal sutures and on

the other side by the root of nose and

supraorbital Rays of either side

pace is an area bounded on one side by

the root of nose and supraorbital Ridge

and on the other side by the junction of

the floor of the mouth with the neck

the occipital region or the occiput is

limited to the occipital bone

this region between the phase and the

occiput is known as the base

regarding the bones there are two

frontal bones anteriorly forming since

put already broke at the center of each

frontal bone is a frontal Eminence these

are the sides of ossification of the

frontal bone during embryological

development although may not be the

first sight frontal bones used to form

only one frontal bone by eight years of

age

there are two parietal Bones superiorly

the ossification centers of parietal

bones are called parietal eminences one

occipital bone lying at the back of the

head and forms the region of the occiput

part of the occipital bone contributes

to the base of the skull as it contains

the foramen magnum which protects the

spinal cord as it leaves the skull

literally there are two temporal bones

talking about the sutures plaid bones of

the Vault are united together by

non-is-fired membranes attached to the

margins of Bones these are called the

sutures and the fontanels the sutures of

obstetric importance are the frontal

suture lies between two frontal Bones

the sagittal or the longitudinal suture

which lies between two parietal Bones

the coronal sutures between parietal and

frontal Bones on either side the

lambdoid sutures between occipital bone

and two parietal bones

and the secret muscle suture between the

temporal bone and the parietal bone

the sutures permit gliding moment of one

bone over the other during childbirth

known as molding talking about the

fontanels a wide Gap in the suture line

is called a fontanel there are almost

six fontanels but only two have the

obstetric importance

first the anterior fountain or blackma

and the posterior Fontanel or Lambda the

anterior fontanelle is formed by the

joining of four sutures the sutures are

anteriorly frontal posteriorly sagittal

and on either side coronal the shape of

the anterior fontanelle is like a

diamond its anteroposterior and

transverse diameters measure

approximately three centimeters each

the floor of the anterior fontanelle is

formed by a membrane and it becomes

ossified 18 months after the birth it

becomes pathological if it fails to

osify even after 24 months posterior

fontanelle is found by Junction of three

suture lines sagittal suture anteriorly

and lambdoid sutures on either sides it

is triangular in shape and measures

about 1.2 by 1.2 centimeters its floor

is membranous but becomes bony at tone

lastly we will discuss about the

diameters of fetal skull the engaging

diameter of the fetal skull depends on

the degree of flexion present the

anterior posterior diameters of head

which may engage are suboxito pragmatic

which extends from the nape of neck to

the center of the bregma this measures

9.5 centimeters and it is the engaging

diameter in case of complete flexion of

the head and vertex presentation

sub occipital frontal which extends from

the nape of the neck to the anterior and

of the anterior fontanelle or center of

the sync support it measures 10

centimeters

and it is the engaging diameter in case

of incomplete flexion and vertex

presentation

occipital frontal extends from the

occipital Eminence to the root of the

nose measuring 11.5 centimeters it is

the engaging diameter in case of marked

deflection of the head and vertex

presentation mental vertical extends

from the midpoint of the chin to the

highest point on the subject and suture

it is 14 centimeters long and it is the

engaging diameter in case of partial

extension of the head and bro

presentation

submanto vertical this diameter extends

from junction of the floor of the mouth

and neck to the highest point on the

sagittal suture it measures 11.5

centimeters and it is the engaging

diameter when there is incomplete

extension of the fetal head and there is

Phase presentation

pragmatic this extends from the junction

of floor of the mouth and neck to the

center of the bagma measures 9.5

centimeters and it is the engaging

diameter in case of complete extension

of the fetal head and face presentation

the transverse diameters which are

concerned in the mechanism of Labor

include biparita diameter measures 9.5

centimeters it extends between two

parietal eminences whatever may be the

position of the head this diameter

nearly always engages

by temporal diameter this measures 8

centimeters it is the distance between

the anterior inferior ends of the

coronal suture or the farthest points on

the coronal suture

so this completes the fetal skull in

this we discussed about the fetal skull

its regions bones sutures fontanels and

the diameters