WordNet

any membranous gap between the bones of the cranium in an infant or fetus (同)fontanel, soft_spot
the irregularly shaped area on either side of the cranium where the frontal bone and the anterior tip of the parietal bone and the temporal bone and the greater wing of the sphenoid bone meet; corresponds to the pterion when bones have ossified (同)sphenoid fontanel, sphenoidal_fontanelle, sphenoidal_fontanel

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/05/15 08:38:40」(JST)

wiki en

A fontanelle (or fontanel) (colloquially, soft spot) is an anatomical feature of the infant human skull comprising any of the soft membranous gaps (sutures) between the cranial bones that make up the calvaria of a fetus or an infant.^[1] Fontanelles allow for rapid stretching and deformation of the neurocranium as the brain expands faster than the surrounding bone can grow.^[2] Premature complete ossification of the sutures is called craniosynostosis.

During infancy, the anterior fontanelle is known as the bregma.

Structure

Fontanelles are soft spots on a baby's head which, during birth, enable the bony plates of the skull to flex, allowing the child's head to pass through the birth canal. The ossification of the bones of the skull causes the anterior fontanelle to close over by 9 to 18 months.^[3] The sphenoidal and posterior fontanelles close during the first few months of life. The closures eventually form the sutures of the neurocranium. Other than the anterior and posterior fontanelles, the mastoid fontanelle and the sphenoidal fontanelle are also significant.

The skull of a newborn consists of five main bones: two frontal bones, two parietal bones, and one occipital bone. These are joined by fibrous sutures, which allow movement that facilitates childbirth and brain growth.

Posterior fontanelle is triangle-shaped. It lies at the junction between the sagittal suture and lambdoid suture. At birth, the skull features a small posterior fontanelle with an open area covered by a tough membrane, where the two parietal bones adjoin the occipital bone (at the lambda). The posterior fontanelles ossify within 2 or 3 months of birth. This is called intramembranous ossification. The mesenchymal connective tissue turns into bone tissue.

Anterior fontanelle is a diamond-shaped membrane-filled space located between the two frontal and two parietal bones of the developing fetal skull. It persists until approximately 18 months after birth. It is at the junction of the coronal suture and sagittal suture. The fetal anterior fontanelle may be palpated until 18 months. In cleidocranial dysostosis, however, it is often late in closing or may never close. Examination of an infant includes palpating the anterior fontanelle.

Two smaller fontanelles are located on each side of the head, more anteriorly the sphenoidal or anterolateral fontanelle (between the sphenoid, parietal, temporal, and frontal bones) and more posteriorly the mastoid or posterolateral fontanelle (between the temporal, occipital, and parietal bones).

Closure

In humans, the sequence of fontanelle closure is as follows:^[2]^[4]

The posterior fontanelle generally closes 1-3 months after birth;
The sphenoidal fontanelle is the next to close around 6 months after birth;
The mastoid fontanelle closes next from 6 to 18 months after birth; and
The anterior fontanelle is generally the last to close between 7-19 months.

Clinical significance

The fontanelle may pulsate, and although the precise cause of this is not known, it is perfectly normal and seems to echo the heartbeat, perhaps via the arterial pulse within the brain vasculature, or in the meninges. This pulsating action is how the soft spot got its name – fontanelle means "little fountain."^{[citation needed]}

Parents may worry that their infant may be more prone to injury at the fontanelles. In fact, although they may colloquially be called "soft-spots", the membrane covering the fontanelles is extremely tough and difficult to penetrate.^{[citation needed]}

Fontanelles allow the infant brain to be imaged using ultrasonography. Once they are closed, most of the brain is inaccessible to ultrasound imaging, because the bony skull presents an acoustic barrier.^{[citation needed]}

Disease

Fontanelles – bulging

A very tense or bulging anterior fontanelle indicates raised intracranial pressure. Increased cranial pressure in infants may cause the fontanelles to bulge or the head to begin to enlarge abnormally.^[5] It can occur due to:^[6]

Encephalitis – swelling (inflammation) of the brain, most often due to infections
Hydrocephalus – a buildup of fluid inside the skull
Meningitis—infection of the membranes covering the brain

Fontanelles – sunken

A sunken (also called "depressed") fontanelle indicates dehydration or malnutrition.^[7]

Fontanelles – enlarged

The fontanelles may be enlarged, may be slow to close or may never close most commonly due to causes like:^[8]

Down syndrome
Hydrocephalus
Intrauterine growth restriction (IUGR)
Premature birth

Rarer causes include:^[8]

Achondroplasia
Apert syndrome
Cleidocranial dysostosis
Congenital rubella
Neonatal hypothyroidism
Osteogenesis imperfecta
Rickets

In other animals

In apes the fontanelles fuse soon after birth. In chimpanzees the anterior fontanelle is fully closed by 3 months of age.^[2]

In dogs

One of the more serious problems that can affect canines is known as an "open fontanelle," which occurs when the skull bones at the top of the head fail to close. The problem is often found in conjunction with hydrocephalus, which is a condition in which too much fluid is found within and around the brain, placing pressure on the brain and surrounding tissues. Often the head will appear dome-shaped, and the open fontanelle is noticeable as a "soft spot" on the top of the dog's head. The fluid-filled spaces within the brain, known as ventricles, also become swollen. The increased pressure damages or prevents the development of brain tissue.^[9]

Not all open fontanelles are connected with hydrocephalus. In many young dogs the skull bones are not fused at birth, but instead will close slowly over a three- to six-month period. Occasionally these bones fail to close, but the dog is still healthy. In these cases, however, the dog's owners need to be very careful, since any injury or bumps to the animal's head could cause significant brain damage, as well as conditions like epilepsy.

Additional images

Fontanelle.
Anterior fontanelle.
Cranial sutures shown from top of head.

References

^ "fontanelle". TheFreeDictionary. Retrieved 24 April 2013.
^ ^a ^b ^c Beasley, Melanie. "Age of Closure of Fontanelles / Sutures". The Center for Academic Research and Training in Anthropogeny (CARTA). Retrieved 24 April 2013.
^ "USMLE Step 2: Secrets".editor1=Theodore X. O'Connell.editor2=Adam Brochert.book=USMLE Step 2: Secrets.ed=3rd.page=271
^ http://www.nlm.nih.gov/medlineplus/ency/article/003310.htm
^ Waxman, Stephen G. Clinical Neuroanatomy. 25th ed. New York: Lange Medical /McGraw-Hill, Medical Pub. Division, 2003.
^ "Fontanelles – bulging". MedlinePlus, U.S. National Library of Medicine & National Institutes of Health. Retrieved 26 April 2013.
^ "Fontanelles – sunken". MedlinePlus, U.S. National Library of Medicine & National Institutes of Health. Retrieved 26 April 2013.
^ ^a ^b "Fontanelles – enlarged". MedlinePlus, U.S. National Library of Medicine & National Institutes of Health. Retrieved 26 April 2013.
^ "Open Skull Bones May, May Not Be Sign of Deadly Disorder". Terrificpets.com. Retrieved 2012-10-24.

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 小児における身体的診察：HEENT the pediatric physical examination heent
2. 新生児の評価 assessment of the newborn infant
3. 頭蓋骨縫合早期癒合症の概要 overview of craniosynostosis
4. 幼児および小児における巨頭症：病因および評価 macrocephaly in infants and children etiology and evaluation
5. 幼児および小児における小頭症：病因および評価 microcephaly in infants and children etiology and evaluation

English Journal

Loss of Tbx1 induces bone phenotypes similar to cleidocranial dysplasia.

Funato N1, Nakamura M2, Richardson JA3, Srivastava D4, Yanagisawa H5.
Human molecular genetics.Hum Mol Genet.2015 Jan 15;24(2):424-35. doi: 10.1093/hmg/ddu458. Epub 2014 Sep 10.
T-box transcription factor, TBX1, is the major candidate gene for 22q11.2 deletion syndrome (DiGeorge/ Velo-cardio-facial syndrome) characterized by facial defects, thymus hypoplasia, cardiovascular anomalies and cleft palates. Here, we report that the loss of Tbx1 in mouse (Tbx1(-/-)) results in sk
PMID 25209980

Efficacy of early neonatal supplementation with vitamin A to reduce mortality in infancy in Haryana, India (Neovita): a randomised, double-blind, placebo-controlled trial.

Mazumder S1, Taneja S1, Bhatia K1, Yoshida S2, Kaur J1, Dube B1, Toteja GS3, Bahl R2, Fontaine O2, Martines J4, Bhandari N5; for the Neovita India Study Group.
Lancet.Lancet.2014 Dec 10. pii: S0140-6736(14)60891-6. doi: 10.1016/S0140-6736(14)60891-6. [Epub ahead of print]
BACKGROUND: Vitamin A supplementation in children aged 6 months to 5 years has been shown to reduce mortality. The efficacy of neonatal supplementation with vitamin A to reduce mortality in the first 6 months of life is plausible but not established. We aimed to assess the efficacy of neonatal oral
PMID 25499546

Effect of early neonatal vitamin A supplementation on mortality during infancy in Ghana (Neovita): a randomised, double-blind, placebo-controlled trial.

Edmond KM1, Newton S2, Shannon C3, O'Leary M3, Hurt L4, Thomas G5, Amenga-Etego S5, Tawiah-Agyemang C5, Gram L3, Hurt CN4, Bahl R6, Owusu-Agyei S7, Kirkwood BR3.
Lancet.Lancet.2014 Dec 10. pii: S0140-6736(14)60880-1. doi: 10.1016/S0140-6736(14)60880-1. [Epub ahead of print]
BACKGROUND: Results of randomised controlled trials of newborn (age 1-3 days) vitamin A supplementation have been inconclusive. The WHO is coordinating three large randomised trials in Ghana, India, and Tanzania (Neovita trials). We present the findings of the Neovita trial in Ghana.METHODS: This st
PMID 25499545

Japanese Journal

Congenital dermoid cyst at the anterior fontanelle: neuroimaging before and after fontanelle closure

Journal of Nippon Medical School 80(1), 83-84, 2013
NAID 130004926718

Congenital Dermoid Cyst at the Anterior Fontanelle: Neuroimaging before and after Fontanelle Closure

Adachi Koji,Ishii Naoko,Takahashi Hiroshi,Teramoto Akira
Journal of Nippon Medical School 79(4), 291-295, 2012
… We report on a 2-month-old boy with a dermoid cyst arising at the anterior fontanelle, with observation during both the open and closed stages of the fontanelle. …
NAID 130004147181

大泉門がウォーム骨により置換されていた Hemifacial microsomia の1例

柳下幹男,土井悠人,山下昌信,川上重彦
日本頭蓋顎顔面外科学会誌 = Journal of the Japan Society of Cranio-Maxillo-Facial Surgery 27(4), 327-333, 2011-12-25
NAID 10030389870

Related Pictures

★リンクテーブル★

リンク元

「泉門」

Fontanelle
	The skull at birth, showing the anterior and posterior fontanelles.
	The skull at birth, showing the lateral fontanelles.
Details
Latin	fonticuli cranii
Identifiers
TA	A02.1.00.027
FMA	75437
	Anatomical terminology

　　[★]

英: fontanelle, fontanelles
ラ: fonticulus, fonticuli cranii
同: 頭蓋泉門
関: [[]]

泉門

[TheFreeDictionary-1] "fontanelle". TheFreeDictionary. Retrieved 24 April 2013.

[CARTA-2] Beasley, Melanie. "Age of Closure of Fontanelles / Sutures". The Center for Academic Research and Training in Anthropogeny (CARTA). Retrieved 24 April 2013.

[3] "USMLE Step 2: Secrets".editor1=Theodore X. O'Connell.editor2=Adam Brochert.book=USMLE Step 2: Secrets.ed=3rd.page=271

[4] ttp://www.nlm.nih.gov/medlineplus/ency/article/003310.htm

[5] Waxman, Stephen G. Clinical Neuroanatomy. 25th ed. New York: Lange Medical /McGraw-Hill, Medical Pub. Division, 2003.

[MedlinePlus_Fontanelles_-_bulging-6] "Fontanelles – bulging". MedlinePlus, U.S. National Library of Medicine & National Institutes of Health. Retrieved 26 April 2013.

[MedlinePlus_Fontanelles_-_sunken-7] "Fontanelles – sunken". MedlinePlus, U.S. National Library of Medicine & National Institutes of Health. Retrieved 26 April 2013.

[MedlinePlus_Fontanelles_-_enlarged-8] "Fontanelles – enlarged". MedlinePlus, U.S. National Library of Medicine & National Institutes of Health. Retrieved 26 April 2013.

[TerrificPets-9] "Open Skull Bones May, May Not Be Sign of Deadly Disorder". Terrificpets.com. Retrieved 2012-10-24.

匿名

検索

案内

案内

fontanelle