Ch. 24 The Fetal Head and Brain Flashcards
The abnormal enlargement of the ventricles within the brain is referred to as ___________.
ventriculomegaly
__________ refers to dilatation (dilation) of the ventricular system caused by an increased volume of CSF, resulting in increased intraventricular pressure. Hydrocephalus may be reserved for cases of ventriculomegaly that are more severe and are caused by some type of obstruction to the flow of CSF, resulting in a backup of the fluid in the cerebral ventricles.
Hydrocephalus
The sonographic finding of the “_________” sign describes the echogenic choroid plexus, hanging limp, and surrounded by CSF, within the dilated lateral ventricle. (this finding is exceedingly specific for ventriculomegaly)
dangling choroid
Ventriculomegaly has been cited as the most common cranial abnormality. Suspicion of ventricular dilatation occurs when the atrial diameter measures more than _______. The lateral ventricle that will be readily seen on sonography is most often the ventricle ________ from the transducer.
10 mm; farthest
what are the two main type of hydrocephalus?
communicating and noncommunicating hydrocephalus
he obstruction of cerebrospinal fluid from a source outside the ventricular system
Communicating hydrocephalus
the obstruction of cerebrospinal fluid from a source within the ventricular system
noncommunicating hydrocephalus
the duct that connects the third ventricle of the brain to the fourth ventricle; also referred to as the aqueduct of Sylvius
aqueductal stenosis
Sonographic Findings of _________
1.Atrium of the lateral ventricle measures greater than 10 mm
2.Atrial measurement greater than 15 mm is considered moderate to marked ventriculomegaly
3.Dangling choroid sign
4.Dilatation of any part of the ventricular system
Ventriculomegaly
______________is the most common cause of hydrocephalus in utero
Aqueductal stenosis
The ___________, located between the third and fourth ventricles of the brain, may be narrowed, thus preventing the flow of CSF from the third to the fourth ventricle. This obstruction level will cause the ________and both the _________ to expand, whereas the fourth ventricle remains normal.
cerebral aqueduct(adqueduct of Sylvius); third ventricle; lateral ventricles
Sonographic Findings of __________
1.Atrium of the lateral ventricle measures greater than 10 mm
2.Atrial measurement greater than 15 mm is considered moderate to marked ventriculomegaly
Dangling choroid sign
Dilatation of the lateral ventricles and the third ventricle; the fourth ventricle remains normal
Aqueductal Stenosis
Sonographic Findings of _________
1.Fluid-filled cranium
2.Absent or partial absence of the falx cerebri
3.Maintained brainstem, basal ganglia, and, perhaps, the thalamus
4.No identifiable cerebral cortex
*fatal condition, with death occuring in the first year of life
Hydranencephaly
___________is a fatal condition in which the entire cerebrum is replaced by a large sac containing CSF
Hydranencephaly
the lower part of the brain composed of the pons, midbrain, and medulla oblongata
brainstem
a group of nuclei within the brain that function in several ways, including information processing and emotional response
basal ganglia
There have been several postulations regarding the cause of _____________, including bilateral occlusion of the internal carotid arteries with subsequent destruction of the cerebral hemispheres. Another hypothesis is that intrauterine infections such as cytomegalovirus and toxoplasmosis lead to the destruction of the cerebral hemispheres.
hydranencephaly
the most severe form of holoprosencephaly
alobar holoprosencephaly
a group of brain abnormalities consisting of varying degrees of fusion of the lateral ventricles, absence of the midline structures, and associated facial anomalies
holoprosencephaly
Hydranencephaly can be difficult to differentiate with the sonographic findings of severe ventriculomegaly and _______ holoprosencephaly. It is important to note that with both severe ventriculomegaly and holoprosencephaly, there will typically be a rim of cerebral tissue maintained, whereas with hydranencephaly, there is ____cerebral mantle present.
alobar; no
one large ventricle within the brain associated with holoprosencephaly
monoventricle
____________is a midline brain anomaly that is associated with not only brain aberrations but also atypical facial structures. It may be detected with endovaginal imaging as early as the first trimester.
Holoprosencephaly
What are the 3 types of holoprosencephaly?
alobar, semilobar, and lobar
What is the severe form of holoprosencephaly? What shapes does it take on?
alobar, “pancake” “cup” “ball”
Although the ______ form can be consistent with life, alobar holoprosencephaly is the most severe form, often resulting in neonatal death.
lobar
With ____________, there will be evidence of a horseshoe-shaped monoventricle, and the lobes of the thalamus may be fused and echogenic in appearance.
holoprosencephaly
the least severe form of the holoprosencephaly
lobar holoprosencephaly
a subdivision within the middle of the lip
median cleft lip
close-set eyes (hypotelorism) and a nose with a single nostril
cebocephaly
the absence of the eye(s)
anophthalmia
Infants with lobar holoprosencephaly may experience severe _______ retardation. _________, or Patau syndrome, is present in 50% to 70% of fetuses diagnosed with holoprosencephaly
mental; Trisomy 13
Facial anomalies associated with _______
Cyclopia
Hypotelorism
Proboscis(false nose above the orbits)
(Median) cleft lip
Anophthalmia
Cebocephaly
alobar holoprosencephaly
Sonographic Findings of __________
1.Horseshoe-shaped monoventricle
2.Fused echogenic thalami
3.Absence of the CSP, interhemispheric fissure, falx cerebri, corpus callosum, and third ventricle
4.Normal cerebellum and brainstem
5.Facial anomalies (e.g., cyclopia, proboscis, cebocephaly, facial clefts, hypotelorism)
Alobar Holoprosencephaly
___________ is actually a classification within a larger group of anomalies referred to as the Dandy–Walker complex. Dandy–Walker complex is a spectrum of posterior fossa abnormalities that involve the cystic dilatation of the _________and __________.
Dandy–Walker malformation (DWM); cisterna magna and fourth ventricle
_________ is thought to be caused by a developmental abnormality in the roof of the fourth ventricle.
DWM
Sonographic Findings of ____________
1.Enlargement of the cisterna magna greater than 10 mm in the anteroposterior dimension
2.Communication of the enlarged cisterna magna with a dilated fourth ventricle
3.Agenesis or hypoplasia of the cerebellar vermis (As a result, the tentorium, the structure that separates the cerebrum from the cerebellum, is elevated)
4.Varying degrees of ventriculomegaly
*There are often other midline brain abnormalities present as well. For instance, agenesis of the corpus callosum, ventriculomegaly, holoprosencephaly, and cephaloceles are all associated anomalies of DWM.
Dandy–Walker Malformation
The sonographic findings of DWM include an enlarged cisterna magna that communicates with a distended _________ through a defect in the cerebellum
fourth ventricle
Sonographic Findings of ________
1.Enlargement of the cisterna magna greater than 10 mm in the anteroposterior dimension
2.Normal cerebellum and fourth ventricle
Mega Cisterna Magna
The __________ is a bridge of tissue located within the midline of the brain that connects the two cerebral hemispheres. It functionally provides a pathway for communication between the hemispheres and is completely formed by ____ weeks.
corpus callosum; 18
The CSP, located inferior to the corpus callosum, and the corpus callosum develop at the _________. The congenital lack of these structures is termed ________, as in _________ of the corpus callosum, and CSP.Most often, if the corpus callosum is absent, the _______ will be absent as well.
same time; agenesis; CSP
Genetic disorder that includes craniosynostosis, midline facial hypoplasia, and syndactly
Apert syndrome
Chromosomal aberration in which there is a third chromosome 8, also referred to as Warkany syndrome 2
trisomy 8
The abnormal lateral ventricle shape in which there is a small frontal horn and enlarged occipital horn
Colpocephaly
Sonographic Findings of ___________ and __________
1.Partial or complete absence of the corpus callosum and absence of the CSP (after 18 weeks)
2.“Sunburst” sign—radial arrangement of the sulci that produces a “spoke-wheel” pattern
3.Colpocephaly—small frontal horns and enlarged occipital horns (teardrop-shaped lateral ventricles)
4.Elevated and dilated third ventricle
*Their nonexistence has been linked to as many as 50 to 200 different syndromes and anomalies such as Apert syndrome, holoprosencephaly, DWM, aqueductal stenosis, trisomy 18, trisomy 8, and trisomy 13.
Agenesis of the Corpus Callosum and Cavum Septum Pellucidum
With agenesis of the _________, the sulci tend to have a more perpendicular or radial arrangement and often appear to have a “spoke-wheel” pattern.
corpus callosum
_____________ is associated with the development of fluid-filled clefts within the cerebrum.
Schizencephaly
The etiology of schizencephaly is unknown, although there may be an association with intrauterine exposure to some illicit drugs. It may be described as _____ lip or _____lip, with ______ lip being more readily identified in utero. The sonographic appearance of open lip schizencephaly is that of a cerebrum containing gray matter–lined _____ filled containing anechoic CSF
open; closed; open; cleft
Sonographic Findings of _________
1.Fluid-filled clefts within the cerebrum
2.Agenesis of the CSP and corpus callosum (50% of the time)
3.Ventriculomegaly
Schizencephaly
_________is a rare condition in which a cyst communicates with the ventricular system. ________ can occur after the fetus has experienced __________ within one or both of the cerebral hemispheres. As the hemorrhage changes states, it will form into a cystic cavity and will eventually communicate with the _________of the affected side. This condition may be caused by ischemic events or vascular occlusion within the brain
Porencephaly; hemorrhage; lateral ventricle
benign cysts within the brain that do not communicate with the ventricular system
Arachnoid cysts
Arachnoid cysts can be confused with porencephaly. It is important to note that arachnoid cysts will ______communicate with the ventricular system.
not
Sonographic Findings of _______
1.Cystic mass that communicates with the lateral ventricle
2.Most often unilateral
Porencephaly
____________literally means “smooth brain.”
Lissencephaly
Agyria, and the absence of sulci within the brain, is not typically diagnosed until the_______trimester or postnatally and almost always carries a poor prognosis.
third
“smooth brain”; condition where there is little to no gyri or sulci within the cerebral cortex
Lissencephaly
Sonographic Findings of __________
Lack of sulci and gyri within the cerebrum
Lissencephaly
_________ are cysts located within the choroid plexus of the lateral ventricles. These small cysts are frequently encountered during a routine sonographic examination and typically regress by the end of the ______ trimester.
Choroid plexus cysts; third
Sonographic Appearance of a __________
Anechoic, round, smooth-walled cyst located within the choroid plexus of the lateral ventricle (measures more than 2mm)
Choroid Plexus Cyst
Choroid plexus cysts often regress, although there is a slight association with trisomy _____.
18
__________occur when the embryonic neural tube fails to close. Among the list of neural tube defects are cephaloceles, various spinal dysraphisms, anencephaly, and spina bifida.
Neural tube defects
a group of neural tube defects that describe some manifestation of incomplete closure of the spine
spinal dysraphisms
a neural tube defect that is described as the absence of the cranium and cerebral hemispheres
anencephaly
________ and _______ are the most common neural defects, occurring in 1 per 1,000 pregnancies. Although several causes have been implicated, such as maternal diabetes and the use of valproic acid (seizure medication), chromosomal anomalies, including Edwards syndrome (trisomy 18), Patau syndrome (trisomy 13), and triploidy, have all been linked with neural tube defects.
Anencephaly and spina bifida
studies have shown that a supplement of 0.4 mg of __________ in a woman’s diet significantly reduces the likelihood of her fetus developing a neural tube defect.
folate (folic acid)
However, increased levels of _____ may not always indicate that a neural tube defect is present. Elevated levels of ______ are also found with omphalocele, gastroschisis, multiple gestations, fetal demise, and incorrect gestational dating.
AFP
________ remains one of the most common neural tube defects. _______ is defined as the absence of the cranial vault above the bony orbits. It can be further divided into two main subtypes depending on the amount of cerebral tissue present, ______ and _______
Acrania; acrania; anencephaly and exencephaly
a form of acrania in which the entire cerebrum is located outside the skull
exencephaly
__________ is considered when there are no cerebral hemispheres present, whereas _________ denotes a normal amount of cerebral tissue. Nonetheless, the cranium is absent, making this condition fatal.
Anencephaly; exencephaly
Clinical Findings of Acrania/Anencephaly
Elevated _______
MSAFP
Sonographic Findings of ________
Absent cranial vault
Some cerebral tissue may be present
“Froglike” facies or bulging eyes
Possible fetal movement and active fetal heart tones
Acrania/Anencephaly
___________ or Chiari II malformation is a group of cranial abnormalities associated with the neural tube defect spina bifida.
Arnold–Chiari II
The most common location of spina bifida is within the __________
distal lumbosacral region
The cerebellum will become displaced inferiorly and posteriorly and appear curved in the presence of spina bifida, which is referred to as the “_______” sign, whereas the head shape will be shaped like a _______ (“________sign”). Remember, when open spina bifida is present, both yellow fruit signs (_________)are demonstrated in the skull.
banana; lemon; lemon sign and banana sign
Clinical Findings of Arnold–Chiari II Malformation
Elevated _________
MSAFP
Sonographic Findings of _________
1.Lemon sign—lemon-shaped cranium with flattened or scalloped frontal bones
2.Banana sign—banana-shaped cerebellum
3.Obliterated cisterna magna
4.Colpocephaly
5.Enlarged massa intermedia
6.Hydrocephalus
7.Open spinal defect
Arnold–Chiari II Malformation
__________ are protrusions of intracranial contents through a defect in the skull
Cephaloceles
Cephaloceles can also be distinguished by their location. The most common location for a cephalocele is in the _______region. However, cephaloceles may also have frontal and parietal positions. _______ cephaloceles often lead to hypertelorism. Encephaloceles, which include brain tissue, are common findings in __________syndrome and have varying sonographic appearances based on their content.
occipital; Anterior; Meckel–Gruber
Clinical Findings of Cephaloceles
Possible elevation of ________
MSAFP
Sonographic Findings of ________
1.Open cranial defect (typically posterior in location)
2.Small or obliterated cisterna magna
3.Complex- or simple-appearing mass protruding from the cranium
Cephaloceles
Type of Cephalocele:
Meningocele
Content of the Mass: _____
Meninges only
Type of Cephalocele:
Encephalocele
Content of the Mass: _____
Brain tissue only
Type of Cephalocele:
Encephalomeningocele
Content of the Mass: _____
Both meninges and brain tissue
Type of Cephalocele:
Encephalomeningocystocele
Content of the Mass: _____
Meninges, brain tissue, and lateral ventricle
Maternal serum screening for intrauterine infections resulting from _______, _________, ________, _________, and __________ (TORCH) can be performed. This is referred to as a TORCH panel
toxoplasmosis, other agents, rubella, cytomegalovirus, and herpes simplex virus
The sonographic intracranial findings consistent with intrauterine infections are the ___________and __________.
calcifications around the ventricles and ventriculomegaly
The most common intracranial tumor found in utero is the _________.
teratoma
_________ contain tissues such as hair, sebum, and fat and most often appear as complex masses that distort the normal architecture of the brain.
Teratomas
Choroid plexus papillomas are found within the ________ and produce an increase in the production of CSF, which, in turn, leads to _________. Other sonographic findings associated with brain tumors are macrocephaly and intracranial calcifications. Corpus callosum lipomas may also be present with _______ of the corpus callosum. A lipoma will appear as a solid echogenic mass.
choroid plexus; ventriculomegaly; agenesis
________ is worrisome for premature infants weighing less than 1,500 g and those born before 32 weeks’ gestation, it occurs less often in utero. Maternal use of cocaine, trauma, and a history of amniocentesis are all listed as predisposing condition of fetal intracranial hemorrhage; however, the most common risk factor for fetal intrauterine intracranial hemorrhage has been listed as _____________
intracranial hemorrhage; maternal platelet disorders
Most often, the origin of ________, also referred to as intraventricular hemorrhage, is within the _________.
intracranial hemorrhage; germinal matrix.
a group of thin-walled blood vessels and cells within the subependymal layer of the fetal brain responsible for brain cell migration during fetal development
germinal matrix
The ________ is a group of thin-walled, pressure-sensitive vessels located in the _________ of the ventricles. These vessels are prone to rupture secondary to their thin walls. The hemorrhage can spread into the lateral ventricle, often leading to noncommunicating hydrocephalus, because the clot obstructs the flow of CSF within the narrowed regions of the ventricular system.
germinal matrix; subependymal layer
the area just beneath the ependymal lining the lateral ventricles
subependymal layer
the functional part of an organ
parenchyma
a shortage of oxygen or decreased oxygen in the blood
hypoxia
an arteriovenous malformation that occurs within the fetal brain and is associated with congestive heart failure
vein of Galen aneurysm
an abnormal accumulation of fluid in at least two fetal body cavities
hydrops (fetal)
Hemorrhage can also occur within the ______ of the brain. Localized areas of hemorrhage within the cerebral hemispheres will eventually lead to the formation of cystic cavities that communicate with the ventricular system, a condition known as __________
parenchyma; porencephaly
The normal cerebral circulation typically yields a _________Doppler pattern, with continuous forward flow throughout the cardiac cycle. Doppler assessment of the middle cerebral artery (MCA) has been shown effective at evaluating for potential _______ in fetuses that are small for dates
high-impedance; hypoxia
When the fetus is starved for oxygen, redistribution of the blood to the vital organs—such as the brain—occurs in order to spare it from damage. This is referred to as the ___________.
brain-sparing effect
The resistance pattern of the MCA should be ________ than that of the umbilical artery and thus should be compared when ________ is suspected.
greater; fetal shunting
The MCA/umbilical artery resistive index is normally above _____, whereas an index lower than _____ is considered abnormal.
1.0; 1.0
The ________ is an arteriovenous malformation that occurs within the fetal brain.
vein of Galen aneurysm
Sonographic Findings of _________
1.Anechoic mass within the midline of the brain that contains turbulent arterial and venous flow when interrogated with pulsed and color Doppler
2.Fetal hydrops
3.Cardiomegaly (caused by cardiac overload)
Vein of Galen Aneurysm
The vein of Galen aneurysm is associated with ________in the newborn.
congestive heart failure
Clinical Findings of _____________(Neonatal)
Congestive heart failure
Vein of Galen Aneurysm
The depth of the cisterna magna should not measure more than _______or less than ______ in the transcerebellar plane. Measurement more than 10 mm is consistent with _______ and ________, whereas a measurement of less than 2 mm is worrisome for________.
10 mm; 2 mm; mega cisterna magna and Dandy–Walker complex; Arnold–Chiari II malformation
The cerebellum grows at a rate of _______per week between 14 and 21 weeks and thus correlates agreeably with the gestational age of the fetus. That means, the cerebellum of a 16-week fetus will measure approximately _______.
1mm; 16mm
The cerebellum is measured in the transverse plane at the same level as the ________and _______. The CSP will also be in the image. This measurement, referred to as the ________, will likely lose its accuracy in the presence of chromosomal abnormalities, typically measuring _______than normal. TCD proven to be useful in several studies as an indicator of growth restriction or large for gestational age when other measurements are lacking.
cisterna magna; thalamus; transcerebellar diameter (TCD); smaller
The lateral ventricle is measured in the transaxial plane at the level of the ______. The _____ of the lateral ventricle is the optimal site for measuring the lateral ventricle, because it is the first region where ventricular enlargement occurs. The calipers are placed at the level of the ______ of the choroid plexus.
atrium; atrium; glomus
The normal lateral ventricle does not typically measure more than _______at the level of the atrium. Enlargement beyond 10 mm is referred to as ________.
10mm; ventriculomegaly
the largest part of the choroid plexus
glomus
the ratio used for assessing fetal head shape
cephalic index
round or short and wide skull
brachycephalic (brachycephaly)
an elongated, narrow head shape; may also be referred to as scaphocephaly
dolichocephaly
normal head shape
mesocephalic
The formula used to calculate the cephalic index considers the BPD and the OFD as follows: cephalic index = _________________
cephalic index = BPD/OFD × 100
A cephalic index of _______________dolichocephalic shape, whereas an index of ____________denotes a brachiocephalic shape.
less than 75; more than 85 denotes
The corrected-BPD is “shape corrected” and is equivalent to the _____, independent of the shape of the skull.
HC
represents the biparietal diameter of a standard-shaped fetal head with the same cross-sectional area
corrected-BPD
The OFD is obtained at the same level of the ______and ______. For the OFD, one caliper is placed in the anterior midline in the middle of the _______bone, whereas the other is placed in the middle of the echogenic line of the _______bone
BPD and HC; frontal; occipital
OFD can also be added to the BPD and multiplied by ______ to obtain an _____.
1.62; HC
_______is obtained in the axial plane at the level of the CSP, thalamus, falx cerebri, and a measurement around the entire cranium is obtained. This is the same level as the third ventricle, which may be seen between the two lobes of the thalamus.Cranial bones must be symmetric on both sides of the head.
HC
HC can also be obtained by measuring the occipitofrontal diameter (OFD) and taking an _________ diameter measurement at the level of the BPD
outer-to-outer diameter
Some authors suggest that the ______ measurement is typically more accurate than BPD because this measurement is independent of the __________, consequently providing a more consistent parameter for estimating gestational age.
HC; fetal head shape
The _______ is obtained in the axial plane at the level of the CSP, thalamus, and falx cerebri. This is the same level as the third ventricle, which may be seen between the two lobes of the thalamus. The cranial bones must be symmetric on both sides of the head, and the measurement is obtained from the ______ table of the proximal parietal bone to the ________ table of the distal parietal bone. That means, the measurement is obtained from leading edge to leading edge (can be taken after the first trimester has ended, typically starting between 13 and 14 weeks)
BPD; outer; inner
The normal cerebellum is a dumbbell-shaped or figure _____–shaped structure noted in the _________ cranium of the fetus. The two hemispheres(right and left) of the cerebellum should be symmetric, although ______ of one cerebellar hemisphere can occur, resulting in the hypoplastic hemisphere appearing smaller than normal.
eight; posterior; hypoplasia
The cerebellum consists of two hemispheres—right and left—that are coupled at the midline by the _______. The _________, named for their shape, are located on the undersurface of the cerebellum and become distorted with spina bifida and Arnold–Chiari malformations.
cerebellar vermis; cerebellar tonsils
The ______, located in the posterior fossa of the cranium, is the largest cistern in the head.
cisterna magna
a prominent space within the skull that contains cerebrospinal fluid; a cistern is created by the separation of the arachnoid membrane and pia mater
cistern
the portion of the cerebellum, located within the midline of the brain, that connects its two hemispheres
cerebellar vermis
On sonography, the _________ appears as an anechoic, fluid-filled space, posterior to the cerebellum, between the cerebellar vermis and the interior surface of the occipital bone. It is considered common to find some small septations within the __________.
cisterna magna
The greater part of CSF is produced by the cells of the ________that are located within the trigone of the lateral ventricles.
choroid plexus
CSF moves from the lateral ventricles into the third ventricle through the ________. From the third ventricle, CSF travels to the fourth ventricle through the _________. Once in the fourth ventricle, the fluid can exit either through the _____ aperture or through the ________apertures. CSF also flows inferiorly and around the spinal cord.
foramina of Monro; cerebral aqueduct; median; lateral
________, also referred to as arachnoid villi, are responsible for the reabsorption of CSF into the venous system. This process occurs at the _________sinus, located along the superior surface of the cerebrum within its midline.
Arachnoid granulations; superior sagittal
nodular structures located along the falx cerebri that reabsorb cerebrospinal fluid into the venous system; also referred to as arachnoid villi
Arachnoid granulations
The ________system is composed of _______ ventricles, whose primary function is to provide cushioning for the brain
ventricular; four
Head Shape:
__________
Associated Anomalies:
Chiari II malformation
Lemon
Head Shape:
__________
Associated Anomalies:
Trisomy 18
Strawberry
Head Shape:
__________
Associated Anomalies:
Thanatophoric dysplasia
Cloverleaf
Head Shape:
__________
Associated Anomalies:
TORCH infections
Trisomy 13 and trisomy 18
Meckel–Gruber syndrome
Fetal alcohol syndrome
Microcephaly
Head Shape:
__________
Associated Anomalies:
Hydrocephalus
Hydranencephaly
Intracranial tumors
Familial inheritance
Beckwith–Wiedemann syndrome
Macrocephaly
Head Shape:
__________
Associated Anomalies:
Craniosynostosis
Trisomy 21
Trisomy 18
Brachycephaly
Head Shape:
__________
Associated Anomalies:
Craniosynostosis
Dolichocephaly
an enlarged head circumference
macrocephaly
small head
microcephaly
Each ventricle is lined by a membrane called the _________. The paired lateral ventricles are located on _________ sides of the falx cerebri within the cerebral hemispheres. They are frequently referred to as right and left ventricles but may also be called the first and second ventricles.
ependyma; both
The divisions of lateral ventricles, called the _______ of the lateral ventricles, like the lobes of the cerebrum, correlate with the adjacent cranial bones. Thus, each lateral ventricle consists of a frontal, a temporal, and an occipital horn. In addition to the horns, the lateral ventricle also has a segment referred to as the _______, which is located between the frontal and occipital horns. The point at which the body, temporal horn, and occipital horn meet is the trigone or _______ of the lateral ventricle.
horns; body; atrium
the lining of the ventricles within the brain
ependyma
specialized cells within the ventricular system responsible for cerebrospinal fluid production
choroid plexus
the protective and nourishing fluid of the brain and spinal cord produced by the cells of the choroid plexus
cerebrospinal fluid (CSF)
Within the atria of both lateral ventricles lies the echogenic configuration of the _________, the mass of cells responsible for the production of ________ in the fetus. Choroid plexus may also be found in the roof of the third and fourth ventricles.
choroid plexus; cerebrospinal fluid (CSF)
a brain structure that allows communication between the senses; also performing many other functions
thalamus
the mass of tissue, located in the third ventricle within the midline of the brain, which connects the two lobes of the thalamus; also referred to as the massa intermedia
massa intermedia or interthalamic adhesion
paired structures located anterior to the cerebral aqueduct
cerebral peduncles
a normal midline brain structure identified in the anterior portion of the brain between the frontal horns of the lateral ventricles
cavum septum pellucidum (CSP)
The two lobes of the thalamus are located on both sides of the _______. The _________ or interthalamic adhesion passes through the third ventricle to connect the two lobes of the thalamus.
third ventricle; massa intermedia
The thalamus should not be confused with the ___________, which are more inferiorly positioned in the brain.
cerebral peduncles
The _______ is a midline brain structure located in the anterior portion of the brain between the frontal horns of the lateral ventricles. It will appear as an anechoic “box-shaped” structure in the axial scan plane. Although the CSP should always be seen between ___ and ____ weeks, the closure of this structure is normal in later gestation and often occurs before birth or shortly thereafter.
cavum septum pellucidum (CSP), 18 and 37 weeks
The CSP does _____ communicate with the ventricular system, and its absence is associated with multiple cerebral malformations, including agenesis of the ________.
not; corpus callosum
The corpus callosum should be intact between how many weeks?
18 and 20 weeks
The corpus callosum consists of ______ parts. Fetal development of the corpus callosum is from __________. Thus, the rostrum, genu, body, and splenium develop, respectively.
four; anterior to posterior
The sonographic appearance of the corpus callosum is that of an _________ band of tissue within the midline of the brain connecting the two cerebral hemispheres
echogenic
The brain can be divided into two main parts, the_______ and the _________. The ________ is the largest part of the brain. The normal cerebrum contains multiple sulci and gyri. There are six cerebral lobes: the _______, ________, ________, and the________.
cerebrum; cerebellum; cerebrum; frontal lobe, 2 parietal, 2 temporal, occipital lobe
grooves within the brain
sulci
folds in the cerebral cortex
gyri
groove within the midline of the brain that divides the two cerebral hemispheres
interhemispheric fissure
a double fold of dura mater located within midline of the brain
falx cerebri
the dense, fibrous outer layer of the meninges
dura mater
a thick band of white matter that provides communication between the right and left halves of the brain
corpus callosum
the coverings of the brain and spinal cord
meninges
the innermost layer of the meninges
pia mater
the middle layer of the meninges
arachnoid membrane
The ______ are three protective tissues layers that cover the brain and the spinal cord. The innermost layer of the meninges is the ______, the middle layer is the _________, and the dense, outermost layer is the _______.
meninges; pia mater; arachnoid membrane; dura mater
The ________separates the cerebral hemispheres, whereas the ________connects the cerebral hemispheres and allows communication between the two lobes.
falx cerebri; corpus callosum
The cerebrum can be further divided into a right and left hemisphere by the ___________. The _______, a double fold of dura mater, is located within the interhemispheric fissure and can readily be noted on a fetal sonogram as an _______ linear formation coursing through the midline of the fetal brain.
interhemispheric fissure; falx cerebri; echogenic
The skull consists of _______ cranial bones. These bones are connected by structures known as _______ . Fetal sutures may be noted during a routine sonographic examination as _________ spaces between the bones. Because of the flexibility of sutures, the fetal cranial bones remain slightly mobile until delivery to facilitate the passage of the skull through the birth canal. Premature fusion of the sutures is termed ________. Consequently, leading to an irregular-shaped skull.
eight; sutures; hypoechoic; craniosynostosis
Spaces that exist between the forming fetal bones are referred to as ________ or “soft spots”. Several fontanelles persist in the postnatal period and into infancy.
fontanelles
Fontanelles are often utilized as sonographic windows during neurosonographic examinations to evaluate newborns for intracranial hemorrhage or suspected brain anomalies. The anterior fontanelle, when completely filled with bone, is referred to as the _______, whereas the posterior fontanelle is referred to as the _______. The _________is the opening in the base of the cranium through which the spinal cord travels.
bregma; lambda; foramen magnum
Each lateral ventricle communicates with the third ventricle in the midline of the brain at the ________, or the paired interventricular foramina. The third ventricle is located between the two lobes of the thalamus. Essentially, part of the thalamus, the interthalamic adhesion or _______, passes through the third ventricle and can be visualized when enlarged or surrounded by CSF.
foramen of Monro; massa intermedia
The third ventricle connects to the fourth ventricle inferiorly by means of a long, tubelike structure called the _________or the cerebral aqueduct.
aqueduct of Sylvius
The fourth ventricle is located _______to the cerebellum within the midline of the brain. The fourth ventricle has ______apertures or openings through which CSF travels. There are ______ lateral apertures that are also referred to as the ________. These two apertures allow CSF to travel from the fourth ventricle to the subarachnoid space around the brain. Another opening of the fourth ventricle, located in the midline, is the median aperture, which is also referred to as the _______. This opening allows CSF to pass from the fourth ventricle to the cisterna magna and subarachnoid space
anterior; 3; two; foramina of Luschka; foramen of Magendie
an opening in a structure
apertures
an area located between the arachnoid membrane and the pia mater
subarachnoid space
By 4.5 weeks, the ________, the structure that will form the central nervous system, has developed.
neural plate
The neural plate will give rise to the _______, which will become the spine and the brain.
neural tube
Initially, the brain is divided into three primary vesicles termed the _______(forebrain), __________(midbrain), and _________(hindbrain)
prosencephalon, mesencephalon, rhombencephalon
the primary brain vesicle also referred to as the forebrain; it eventually becomes the lateral ventricles, cerebral hemispheres, third ventricle, thalamus, hypothalamus, pineal gland, and pituitary gland
prosencephalon
the primary brain vesicle also referred to as the midbrain; it eventually becomes the cerebral peduncles, quadrigeminal plate, and cerebral aqueduct
mesencephalon
the primary brain vesicle also referred to as the hindbrain; it eventually becomes the cerebellum, pons, medulla oblongata, and fourth ventricle
rhombencephalon
Further division of the primary vesicles : Prosencephalon divides to (________&________), Mesencephalon, Rhombencephalon divides to (________and _______)
telencephalon & diencephalon, metencephalon and myelencephalon
Which of the following is a genetic disorder that includes craniosynostosis, midline facial hypoplasia, and syndactyly?
a. lobar holoprosencephaly
b. Beckwith-Wiedemann syndrome
c. Arnold-Chiari II malformation
d. Apert syndrome
d. Apert syndrome
The third ventricle communicates with the fourth ventricle at the:
a. foramen of Magendie
b. foramen of Luschka
c. foramen of Monro
d. aqueduct of Sylvius
d
The fourth ventricle is located:
a. posterior to the CSP
b. between the frontal horns of the lateral ventricles
c. anterior to the cerebellar vermis
d. medial to the third ventricle
c
What is the most accurate head measurement for estimating gestational age in the second trimester?
a. BPD
b. HC
c. transcerebellar measurement
d. lateral ventricles
b
All of the following are sonographic features of alobar holoprosencephaly except:
a. cyclopia
b. monoventricle
c. dorsal cyst
d. fused thalamus
c
Suture:
_________
Location:
Between the frontal and two parietal bones
Coronal suture
Suture:
_________
Location:
Between the two parietal bones
Sagittal suture
Suture:
_________
Location:
Between the parietal bones and occipital bone
Lambdoidal suture
Suture:
_________
Location:
Between the parietal bones and temporal bones
Squamosal sutures
Suture:
_________
Location:
Located within the frontal bone along the midline of the forehead
Metopic suture
Cranial Bone(s) & put there location
Frontal bone
Parietal bones
Temporal bones
Occipital bone
Sphenoid bone
Ethmoid bone
Frontal bone: Anterior
Parietal bones: Superior and lateral
Temporal bones:
Inferior and lateral
Occipital bone:
Posterior
Sphenoid bone:
Lateral (helps form the base of the skull)
Ethmoid bone:
Anterior (between the orbits)
Fontanelle:
_________
Location:
Bordered by the frontal and parietal bones
Closure: By 18 mo
anterior or frontal
Fontanelle:
_________
Location:
Bordered by the occipital and parietal bones
Closure: By 6 mo
posterior or occipital
Fontanelle:
_________
Location:
Bordered by the frontal, parietal, and sphenoid bones
Closure: By 2 yr
anterolateral or sphenoidal
Fontanelle:
_________
Location:
Bordered by the mastoid and occipital bones
Closure: By 2 yr
posterolateral or mastoid
Midline brain anatomy or bilateral?
Falx cerebri
Interhemispheric fissure
Corpus callosum
Cavum septum pellucidum
Third ventricle
Aqueduct of Sylvius (cerebral aqueduct)
Fourth ventricle
Cerebellar vermis
Cisterna magna
Interthalamic adhesion (massa intermedia)
Brainstem (pons, midbrain, and medulla oblongata)
midline brain anatomy
Midline brain anatomy or bilateral?Hemispheres of the cerebellum
Hemispheres of the cerebrum
Lobes of the thalamus
Foramen of Monro (interventricular foramina)
Lateral ventricles
Choroid plexus (within lateral ventricles)
bilateral
