27 MAGNETIC RESONANCE VENOGRAPHY: CORONAL AND SAGITTAL VIEWS

Vasculature



103



Parts of cerebellum



Left superior and inferior colliculi



L

CL

C

D

F



Left pulvinar



Basal vein (of Rosenthal)



Right thalamus



Posterior mesencephalic vein



TU

P

U

N

T



lingula

central lobule

culmen

declive

folium



tuber

pyramid

uvula

nodule

tonsil



Interior cerebral veins



Medial geniculate body



Splenium of corpus callosum



Lateral mesencephalic vein

Cut surface of

left thalamus



Great cerebral vein (of Galen)

Inferior sagittal sinus

Superior

cerebellar

vein

(inconstant)

Superior

vermian

vein

Straight

sinus

Falx cerebri



Lateral geniculate

body

Optic tract

Inferior thalamobstriate vein

Anterior

cerebral vein

Optic (II)

nerve

Deep

middle

cerebral

vein



C



Superior

sagittal sinus



C



CL



F



L



Anterior

pontomesencephalic

vein

Trigeminal

(V) nerve

Petrosal vein

(draining to

superior

petrosal sinus)

Transverse pontine vein

Vestibulocochlear (VIII) nerve



Tentorium

cerebelli (cut)

Intraculminate

vein

Preculminate vein



D

TU

P



N



Confluence

of sinuses



U



Left transverse sinus

Inferior vermian vein

Falx cerebelli

(cut) and occipital sinus



T



Facial (VII) vein

Anterior medullary vein

Vein of lateral recess of 4th ventricle

Superior, middle, and

inferior cerebellar peduncles

4th ventricle



Inferior cerebellar

hemispheric vein

Precentral vein

Left lateral brachial vein

Inferior retrotonsillar vein

Superior retrotonsillar vein

Posterior spinal vein



Anterior spinal vein



7.28  VENOUS DRAINAGE OF THE BRAIN STEM

AND THE CEREBELLUM

The venous drainage of the cerebellum and the brain stem is

anatomically diverse. The veins of the posterior fossa drain the

cerebellum and brain stem. The superior group drains the superior cerebellum and upper brain stem posteriorly into the

great cerebral vein of Galen and the straight sinus or laterally

into the transverse and superior petrosal sinuses. The anterior,

or petrosal, group drains the anterior brain stem, the superior

and inferior surfaces of the cerebellar hemispheres, and the

lateral regions associated with the fourth ventricle into the superior petrosal sinus. The posterior, or tentorial, group drains



the inferior portion of the cerebellar vermis and the medial

portion of the superior and inferior cerebellar hemispheres

into the transverse sinus or the straight sinus.

CLINICAL POINT

The confluence of sinuses occurs at the junction of the posterior �fossa

and the occipital lobe. The superior sagittal sinus drains into this confluence of sinuses as the blood flows ultimately toward the jugular

vein. The most common sinus thrombosis is that of the superior sagittal sinus. Thrombosis in the posterior portion of this sinus results in

headache, increased intracranial pressure with resultant papilledema

)>>after 24 hours), and often a diminished state of consciousness or

coma.



104



Overview of the Nervous System



Veins of Spinal Cord and Vertebrae



Anterior external venous plexus

Posterior external venous plexus

Anterior internal venous plexus

Intervertebral vein

Basivertebral vein



Anterior external

venous plexus



Anterior internal

venous plexus



Basivertebral vein

Anterior and posterior

radicular veins

Anterior spinal vein

Anterior central vein



Basivertebral vein



Posterior internal

venous plexus



Anterior internal

venous plexus



Intervertebral vein



Posterior external

venous plexus



Intervertebral vein

Anterior radicular vein

Posterior radicular vein

Internal spinal veins

Pial venous plexus

Posterior central vein

Posterior spinal vein

Posterior internal venous plexus



7.29  VENOUS DRAINAGE OF THE SPINAL CORD

An external and internal plexus of veins extends along the entire length of the vertebral column, forming a series of venous

rings with extensive anastomoses around each vertebra. Blood

from the spinal cord, the vertebrae, and the ligaments drains

into these plexuses. Changes in intrathoracic pressure and cerebrospinal fluid pressure can be conveyed through these venous plexuses, affecting the venous volume. Ultimately, these

venous plexuses drain through the intervertebral veins into

vertebral, posterior intercostals, subcostal, and lumbar and

lateral sacral veins.



CLINICAL POINT

A venous plexus is present in the epidural space surrounding the spinal cord, along with epidural fat. This epidural space is wide enough

for the insertion of a catheter and infusion of local anesthesia. The

local anesthesia is absorbed into this plexus and diffuses into the adjacent spinal cord, producing profound analgesia at and below the level

of the infusion. This technique of epidural anesthesia often is used

for analgesia in childbirth and also for a variety of surgeries in which

epidural anesthesia is preferable to general anesthesia.



8

8.1

8.2

8.3

8.4

8.5

8.6

8.7

8.8

8.9

8.10

8.11

8.12

8.13



DEVELOPMENTAL

NEUROSCIENCE



F

 ormation of the Neural Plate, Neural Tube,

and Neural Crest

N

 eurulation

N

 eural Tube Development and Neural Crest

�Formation

D

 evelopment of Peripheral Axons

S

 omatic Versus Splanchnic Nerve Development

L

 imb Rotation and Dermatomes

N

 eural Proliferation and Differentiation: Walls

of the Neural Tube

N

 eural Tube and Neural Crest Derivatives

E

 arly Brain Development: The 28-Day-Old Embryo

E

 arly Brain Development: The 36-Day-Old Embryo

E

 arly Brain Development: The 49-Day-Old Embryo

and the 3-Month-Old Embryo

F

 orebrain Development: 7 Weeks through 3 Months

T

 he 6-Month and 9-Month Central Nervous Systems



8.14

8.15

8.16

8.17

8.18

8.19

8.20

8.21

8.22

8.23

8.24

8.25

8.26



C

 omparison of 5½ Week and Adult Central Â�Nervous

System Regions

A

 lar and Basal Plate Derivatives in the Brain Stem

A

 dult Derivatives of the Forebrain, Midbrain, and

Hindbrain

C

 ranial Nerve Primordia

C

 ranial Nerve Neuron Components

D

 evelopment of Motor and Preganglionic Autonomic

Nuclei in the Brain Stem and Spinal Cord

D

 evelopment of the Eye and Orbit

D

 evelopment of the Ear

D

 evelopment of the Pituitary Gland

D

 evelopment of the Ventricles

D

 evelopment of the Fourth Ventricule

N

 eural Tube Defects

D

 efects of the Brain and Skull



105



106



Overview of the Nervous System



Oropharyngeal membrane

Lens placode

Olfactory placode



Notochord



Hypophysis



Paraxial column

Intermediate column

Appearance of the neural plate

Lateral plate



Optic area



Forebrain

Midbrain

Hindbrain

Neural crest

Neural plate forming neural tube

Somite



Axial rudiment

Spinal cord

Neural crest



Intermediate mesoderm

Intraembryonic coelom



Developmental fates of local regions

of ectoderm of embryonic disc at 18 days



Notochord



8.1  FORMATION OF THE NEURAL PLATE,

�NEURAL TUBE, AND NEURAL CREST

The neural plate, neural tube, and neural crest form at the

18-day stage of embryonic development. The underlying

�notochord induces the neural plate, and a midline neural

groove forms. The elevated lateral margins become the neural



folds, tissue destined to become the neural crest with future

contributions to many components of the peripheral nervous

system (PNS). At this very early stage of embryonic development, these neural precursors are vulnerable to toxic and

other forms of insult.



Developmental Neuroscience



107



Future neural crest

Ectoderm



Neural plate of forebrain



Neural plate



Level of section

Neural groove

Neural groove

Neural folds

2.0 mm



Future neural crest



Neural fold



Level of section

1st occipital somite



Primitive streak



Embryo at 20 days (dorsal view)



Neural plate of forebrain

Neural crest

Neural groove



Level of section



2.3 mm



Neural folds



Fused neural folds



1st cervical somite



Caudal neuropore

Embryo at 21 days (dorsal view)



8.2  NEURULATION

In the 21- or 22-day-old-embryo, the neural plate, with its

midline neorural groove, thickens and begins to fold and elevate along either side, allowing the two lateral edges to fuse

at the dorsal midline to form the completed neural tube. The

central canal, the site of the future development of the ventricular system, is in the center of the neural tube. This process

of neurulation continues both caudally and rostrally. Disruption can occur because of failure of full neural tube formation

caudally (spina bifida) or rostrally (anencephaly).



CLINICAL POINT

As the neural plate forms into a neural tube, the process of neurulation

results in fused neural folds, starting centrally and moving both caudally and rostrally. Failure of the neural tube to close results in dysraphic

�defects, with altered development of associated muscles, bone, skin, and

meninges. If the anterior neuropore fails to form, anencephaly results,

with failure of the brain to develop, accompanied by facial defects. This

condition is lethal. Failure of the posterior (caudal) neuropore to close results in spina bifida, with failure of the vertebral arches to fuse. A saccular

protrusion from the lumbar region may contain meninges (meningocele)

or meninges and spinal cord (meningomyelocele). Meningomyelocele is

�often accompanied by paraparesis, bowel and bladder dysfunction, sensory disruption at the level of the lesion, and accompanying hydrocephalus or Arnold-Chiari malformation, requiring a ventriculo-peritoneal or

ventriculo-jugular shunt.