ANAT2341 Lab 6 - Postnatal: Difference between revisions

Revision as of 10:27, 10 September 2014

Introduction

Fetal Head (12 weeks) showing bone and cartilage

The Skull is a unique skeletal structure in several ways: embryonic cellular origin (neural crest), form of ossification (intramembranous and endochondrial) and flexibility (fibrous sutures).

The cranial vault (which encloses the brain) bones are formed by intramembranous ossification.
While the bones that form the base of the skull are formed by endochondrial ossification.
The bones enclosing the brain have large flexible fibrous joints (sutures) which allow:

the head to pass through the birth canal
postnatal brain growth

ossification continues postnatally, through puberty until mid 20s.
in old age the sutures separating the vault plates are often completely ossified.
Flexible fibrous sutures allow growth of the brain to be accomodated by calvarial plate growth.
Recent molecular studies have show that noggin (a BMP antagonist) is involved in closure of these sutures.

Postnatal Skull

Skull CT Vertex, later and basal views.^[1]

rapid brain growth in the early years of life (growth of the neurocranium stopping at about 7 years of age).
fontanels usually close by the second year of life
- posterior fontanel by about 3 months.
- anterior fontanel by about 20 months.
Complete sutural fusion occurs after the third decade of life.

Sutures and Fontanels

a - Metopic suture
b - coronal sutures
c - sagittal suture
d - lambdoid suture
e - squamosal suture
f - anterior fontanel
g - posterior fontanel
h - sphenoidal fontanel
i - mastoid fontanel

Adult Skull MRI

Links:

Skull Development

- MRI

‎‎Viscerocranium

Page | Play

‎‎Temporal Bones

Page | Play

‎‎Occipital - Frontal

Page | Play

‎‎Parietal-Zygomatic

Page | Play

Additional Information

Head Growth

Head growth and corresponding charts differ slightly for girls and boys. Given as head circumference-for-age Birth to: 13 weeks, 2 years, 5 years.

Girls	Boys

Chart PDF \| WHO - Girls	Chart PDF \| WHO - Boys

Links: Growth Charts | Neural Exam Movies | - Standard Head circumference-for-age | WHO Growth Standards

Bone Histology

A histological image of a skull bone formation by Intramembranous ossification.

References

↑ <pubmed>21431034</pubmed>| PMC3056371 | Indian J Radiol Imaging.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2026, September 26) Embryology ANAT2341 Lab 6 - Postnatal. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/ANAT2341_Lab_6_-_Postnatal

What Links Here?

[PMID21431034-1] <pubmed>21431034</pubmed>| PMC3056371 | Indian J Radiol Imaging.

[1]

@@ Line 16: / Line 16: @@
 * Recent molecular studies have show that '''noggin''' (a BMP antagonist) is involved in closure of these sutures.
-==Fetal Head Growth==
+==Postnatal Skull==
 {|
-| [[File:Fetal_head_growth_circumference_graph02.jpg|400px]]
+| [[File:Skull CT normal sutures.jpg|600px]]
-| [[File:Fetal_head_growth_circumference_graph01.jpg|400px]]
-|}
-:'''Links:''' [[Book_-_Contributions_to_Embryology_Carnegie_Institution_No.48|Historic - Human Fetus (CRL 43mm) Skull]]
+Skull CT Vertex, later and basal views.<ref name="PMID21431034"><pubmed>21431034</pubmed>| [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3056371 PMC3056371] | [http://www.ijri.org/article.asp?issn=0971-3026;year=2011;volume=21;issue=1;spage=49;epage=56;aulast=Khanna Indian J Radiol Imaging.]</ref>
+| valign=top|
+* rapid brain growth in the early years of life (growth of the neurocranium stopping at about 7 years of age).
+* fontanels usually close by the second year of life
+** posterior fontanel by about 3 months.
+** anterior fontanel by about 20 months.
+* Complete sutural fusion occurs after the third decade of life.
-== Skull Views ==
+'''Sutures and Fontanels'''
-{| class="prettytable"
+* '''a''' - Metopic suture
-| [[File:Skull anterior.gif]]
+* '''b''' - coronal sutures
-| [[File:Skull_superior.gif]]
+* '''c''' - sagittal suture
-| [[File:Skull lateral view.gif]]
+* '''d''' - lambdoid suture
+* '''e''' - squamosal suture
+* '''f''' - anterior fontanel
+* '''g''' - posterior fontanel
+* '''h''' - sphenoidal fontanel
+* '''i''' - mastoid fontanel
-|-
+{{Adult skull movies}}
-| anterior view
+|}
-| superior view
-| lateral view
-|-
+==Additional Information==
-| showing anterior fontenelle, sutures, mandible
-| showing anterior fontenelle, sutures
-| showing suture, mandible
-|}
+===Head Growth===
+Head growth and corresponding charts differ slightly for girls and boys. Given as head circumference-for-age Birth to: 13 weeks, 2 years, 5 years.
-== Skull Sutures ==
-[[File:Human_skull_lateral_simplified.png|thumb|Adult Skull]]
 {|
-| Computed Tomography (CT) scan with 3D surface-rendered reconstructions.<ref><pubmed>21431034</pubmed>| [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3056371 PMC3056371] | [http://www.ijri.org/article.asp?issn=0971-3026;year=2011;volume=21;issue=1;spage=49;epage=56;aulast=Khanna Indian J Radiol Imaging.]</ref>
+! Girls
+! Boys
-'''Vertex (A) and lateral (B) views'''.
+|-
-* (a) Metopic suture; (b) coronal sutures; (c) sagittal suture; (d) lambdoid suture; (e) squamosal suture; (f) anterior fontanel; (g) posterior fontanel; (h) sphenoidal fontanel; (i) mastoid fontanel.
+| [[File:WHO chart - girls head birth to 5 years.png|400px]]
-* Cranial vault bones usually ossify from the center to periphery, which results in this “widened” appearance of the sutures in the newborn.
+| [[File:WHO chart - boys head birth to 5 years.png|400px]]
+|-
-'''Endocranial skull base view''' (C) shows portions of the occipital bone and sutures
+| [[Media:WHO chart - girls head birth to 5 years.png|Chart PDF]] | [http://www.who.int/childgrowth/standards/second_set/chts_hcfa_girls_p/en/index.html WHO - Girls]
-* (j) Basioccipital; (k) paired exoccipital; (l) supraoccipital; and (m) interparietal. Associated synchondroses are (n) spheno-occipital; (o)anterior intra-occipital; (p) posterior intra-occipital; (q) petro-occipital; (r) occipitomastoid; (s) and mendosal sutures. Note that o, k, p and s are paired structures.
+| [[Media:WHO chart - boys head birth to 5 years.png|Chart PDF]] | [http://www.who.int/childgrowth/standards/second_set/chts_hcfa_boys_p/en/index.html WHO - Boys]
-'''Vertex view''' (D) shows the lambda (point of intersection of the sagittal and lambdoid sutures) and bregma (point of intersection of the coronal and sagittal sutures.
-'''Endocranial skull base view''' (E) shows the basion (located on the basiocciput, at the midpoint of the anterior margin of the foramen magnum) and opisthion (located on the occipital bone, at the midpoint of the posterior margin of the foramen magnum).
-| [[File:Skull CT normal sutures.jpg|600px]]
-|}
-The bones enclosing the brain have large flexible fibrous joints (sutures) which allow firstly the head to compress and pass through the birth canal and secondly to postnatally expand for brain growth. (More? [[#Molecular_Skull_Sutures|Molecular Skull Sutures]]) These sutures gradually fuse at different times postnatally, firstly the metopic suture in infancy and the others much later. Abnormal fusion (synostosis) of any of the sutures will lead to a number of different skull defects, leading to disruption of brain development. (More? [[#Abnormal_Synostosis|Abnormal Synostosis]]) In old age all these sutures are generally completely fused and ossified.
-At the molecular level, accelerated suture intramembranous ossification can be mediated through a dual role of β-catenin in both the expansion of osteoprogenitors and the maturation of osteoblasts.<ref><pubmed>17113065</pubmed></ref> These researchers also show that disruption of Axin2/β-catenin signaling alters the regulation of the downstream transcription target, cyclin D1, in the canonical Wnt pathway.Pubmed: 21108844
-'''coronal suture'''
-'''lambdoid suture'''
-'''metopic suture''' begins at nose and runs superiorly to meet sagittal suture and fuses during infancy (fusion beginning at 3 months and completes by 6 to 8 months of age) before all other cranial sutures.
-'''sagittal suture'''
-== Abnormal Synostosis ==
-There are several skull deformities caused by premature fusion (synostosis) of different developing skull sutures. Suture abnormalities are classified as either "simple" (only one suture involved) or "compound" (two or more sutures involved).
-{| class="prettytable"
-| <center>[[File:Oxycephaly.jpg|300px]] </center>
-<center>Oxycephalus (historic image from Hess, 1922) </center>
-| * '''craniosynostosis''' premature cranial suture fusion, results in an abnormal skull shape, blindness and mental retardation.
-* '''oxycephaly''' (tower skull) results from premature coronal suture synostosis.
-* '''plagiocephaly''' results from asymmetric coronal suture synostosis, incidence is approximately 1 in 300 live births.
-* '''lambdoid synostosis''' results from premature lambdoid suture synostosis, a rare abnormality (incidence is approximately 3 in 100,000 live births) which displaces ear posteriorly towards the fused suture.
-* '''caphocephaly''' results from premature sagittal suture synostosis.
-* '''trigoncephaly''' (wedge skull) results from metopic suture synostosis.
 |}
-=== Craniosynostosis ===
-Attenuation of signaling pathways stimulated by pathologically activated FGF-receptor 2 mutants prevents craniosynostosis.<ref><pubmed>17132737</pubmed></ref> "Craniosynostosis, the fusion of one or more of the sutures of the skull vault before the brain completes its growth, is a common (1 in 2,500 births) craniofacial abnormality, approximately 20% of which occurrences are caused by gain-of-function mutations in FGF receptors (FGFRs). ...These experiments show that attenuation of FGFR signaling by pharmacological intervention could be applied for the treatment of craniosynostosis or other severe bone disorders caused by mutations in FGFRs that currently have no treatment."
-=== Craniofrontonasal Syndrome ===
+:Links: [[Postnatal_-_Growth_Charts|Growth Charts]] | [[Neural Exam Movies]] | [http://www.who.int/childgrowth/standards/hc_for_age/en/index.html - Standard Head circumference-for-age] | [http://www.who.int/childgrowth/en/ WHO Growth Standards]
-Craniofrontonasal syndrome (CFNS) is a human X-linked developmental disorder caused by a mutation in ephrin-B1 affecting mainly females. Characterised by abnormal development of cranial and nasal bones, craniosynostosis (premature coronal suture fusion), and other extracranial anomalies (limb [[P#polydactyly|polydactyly]] and [[S#syndactyly|syndactyly]]).
-{| class="prettytable"
-| [[File:Craniofrontonasal syndrome.jpg|600px]]
-| (a) Facial view showing marked hypertelorism, divergent squint, and central nasal groove (subject age, 1 year).
+:Links: [[Postnatal_-_Growth_Charts|Growth Charts]] | [[Neural Exam Movies]] | [http://www.who.int/childgrowth/standards/hc_for_age/en/index.html - Standard Head circumference-for-age] | [http://www.who.int/childgrowth/en/ WHO Growth Standards]
-(b) Three-dimensional computed tomographic skull reconstruction (subject age, 8 months) showing right unicoronal synostosis, lateral displacement of orbits, and central defect between frontal bones. Note bony ridge at site of obliterated right coronal suture (arrowhead); the left coronal suture is patent (arrow). f, frontal bone; p, parietal bone.
+===Bone Histology===
-(c) Longitudinal splitting of the nails is frequent.
-|-
-| Craniofrontonasal syndrome<ref><pubmed>15166289</pubmed>| [http://www.pnas.org/content/101/23/8652.full PNAS Link]</ref>
-| '''Links:''' [http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=304110 OMIM - Craniofrontonasal Syndrome]
-|}
-== Skull Bone Histology ==
 A histological image of a skull bone formation by Intramembranous ossification.