1. COVERINGS OF BRAIN & SPINAL
CORD/
DURAL VENOUS SINUSES
BY
PROF. DR. ANSARI
( FOR DENTAL STUDENTS SEMESTER-II)
Tuesday, January 07, 2014
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2. A clinical case
A 25-year-old man is involved in an automobile accident and
slams his head into a concrete wall of a bridge.
His computed tomography (CT) scan reveals that the middle
meningeal artery has ruptured but the meninges remain intact.
Blood leaking from this artery enters which of the following
spaces?
A. Subarachnoid space
B. Subdural space
C. Epidural space
D. Subpial space
E. Cranial Dural sinuses
Tuesday, January 07, 2014
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3. The protective coverings of central
nervous system
• There are three coverings that protect the
brain and spinal cord.
• Apart from protection they carry venous
blood/sinuses.
• They constitute the blood brain barrier.
• They drain (CSF) the cerebrospinal fluid.
• The outer layer is Dura, intermediate layer is
arachnoid and inner layer is pia mater.
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5. The cranial Dura
• It is double layered, periosteal layer and
menningeal layer. The meningeal layer continues
as the spinal dural.
• The falx cerebri separates the right from the left
cerebral hemisphere, the tentorium cerebelli
separates the occipital lobe of the cerebrum from
the underlying cerebellum, and the diaphragma
sellae forms a circular partition around the stalk
of the pituitary gland.
• The medial edge of the tentorium cerebelli is
called the tentorial incisure.
• The falx cerebelli separates the two cerebellar
hemisphere, and attached to the inner surface of
tentorium cerebelli.
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7. The spinal dura is single layered
• It extends below the spinal cord and ends as a sac
at the level of lower border of second sacral
vertebra
1. Intervertebral disc
2. Vertebral body
3. Dura mater
4. Extradural /epidural space
5. Spinal cord
6. Subarachnoid space
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8. The falx cerebri is a sickle shaped fold
of dura mater
• It has an attached border enclosing superior
sagittal sinus.
• It has a free border enclosing inferior sagittal
sinus.
• The falx separates the right from left cerebral
hemispheres.
• It is attached anteriorly to crista galli and frontal
crest.
• Posteriorly it is inserted into tentorium cerebelli,
enclosing straight sinus.
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11. The diaphragma sellae
• The sellar diaphragm is the smallest dural
infolding and is a circular sheet of dura that is
suspended between the clinoid processes,
forming a partial roof over the hypophysial
fossa.
• The sellar diaphgram covers the pituitary
gland in this fossa and has an aperture for
passage of the infundibulum (pituitary stalk)
and hypophysial veins.
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13. Blood supply to the dura
• Middle meningeal artery is a branch from
maxillary, enters the cranial cavity via foramen
spinosum.
• Accessory middle meningeal artery branch
from maxillary.
• Meningeal branches from internal carotid and
vertebral arteries.
• Posterior & anterior ethmoidal arteries,
branches of ophthalmic artery.
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16. 1=layers of scalp;2=occipital bone;3=lacuna
lateralis;4=middle meningeal vessels;
5=superior sagital sinus
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17. Innervations of dura
• Sensory innervations of the supratentorial
dura mater is via small meningeal branches of
the trigeminal nerve (V1, V2 and V3).
• The innervations for the infratentorial dura
mater are upper cervical nerves.
• The dura of posterior cranial fossa is supplied
by glossopharyngeal, vagus and cervical
nerves.
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18. A clinical case
A 63 year old man has thrombosis of the cavernous sinus. Three days
earlier he developed an infection after the extraction of an upper
molar tooth.
The most likely route through which the infection reached the
cavernous sinus is through which of the following venous channels:-
A. Angular vein
B. Inferior alveolar vein
C. Pterygoid plexus of veins
D. inferior ophthalmic vein
E. External jugular vein
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19. The dural venous sinuses are spaces between
the endosteal and meningeal layers of the dura.
• They contain venous blood that originates for the
most part from the brain or cranial cavity.
• The sinuses contain an endothelial lining that is
continuous into the veins that are connected to
them.
• There are no valves in the sinuses or in the veins
that are connected to the sinuses, their tunica lacks
muscular layer.
• The vast majority of the venous blood in the sinus
drains from the cranium via the internal jugular
vein.
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20. •
A.
Superior Sagittal Sinus
B.
Great Cerebral Vein
C.
Ophthalmic Veins
D.
Facial Vein
E.
Cavernous Sinus
F.
Inferior Petrosal Sinus
G.
Jugular Vein
H.
Sigmoid Sinus
I.
Superior Petrosal Sinus
J.
K.
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Transverse Sinus
Straight Sinus
L.
Inferior Sagittal Sinus
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22. The Cavernous Sinuses
A. Carotid Artery
G. Cavernous sinus.
B. Trochlear Nerve
H.Ophthalmic nerve.
C. Maxillary Nerve
I.Oculomotor nerve.
D. Abducens Nerve
E. Sphenoid Sinus
F. Pituitary Gland
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23. All dural venous sinuses end up into
Jugular foramen, as internal jugular vein
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24. A clinical case
A 14-year-old boy hits his head on the asphalt road
after falling off his skateboard. His radiograph
reveals damage to the sella turcica.
This is probably due to fracture of which of the
following bones?
A. Frontal bone
B. Ethmoid bone
C. Temporal hone
D. Basioccipital bone
E. Sphenoid bone
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25. A clinical case
A 67-year-old woman comes to her physician complaining
of visual loss. Her magnetic resonance imaging (MRI) scan
shows an enlarged pituitary gland that lies in the sella
turcica, immediately posterior and superior to which of
the following structures?
A. Frontal sinus
B. Maxillary sinus
C. Ethmoid air cells
D. Mastoid air cells
E. Sphenoid sinus
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26. A clinical case
• A 9 year old boy was brought by his mother to
the A&E department within an 18 hours of
pyrexia and vomitting.When he was seen by
the pediatric doctor, the child complained that
the lights in the examination cubicle were
hurting his eyes( photophobia). He was noted
to have stiff and painful neck.
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28. Epidural hemorrhage or extradural hemorrhages are
usually caused by tears in arteries
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29. Extradural/epidural hemorrhages
• A blow to the head may cause instant deformation of
the skull without a fracture. This, too, can cause
vascular tears.
• Bleeding from these vessels lifts the dura off of the
skull forming an epidural blood clot.
• Epidural hematomas develop most commonly with
fractures of the squamous portions of the temporal
and parietal bones that tear the middle meningeal
vessels.
• Epidural and subdural hematomas, merely compress
the brain and raise the intracranial pressure.
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30. SUB DURAL HEMORRAGE
resulting from tears in bridging veins which cross the subdural space
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31. Subarachnoid hemorrhages
• Subarachnoid hemorrhage is the most frequent
traumatic brain lesion.
• It results from rupture of corticomeningeal vessels and
from hemorrhagic contusions of the brain.
• Blood is diluted by the CSF and does not clot unless it
is massive.
• A large subarachnoid hemorrhage raises the
intracranial pressure, impairs cerebral perfusion.
• Hemoglobin released from RBCs in the subarachnoid
space triggers vascular spasm. It also incites fibrosis of
the arachnoid membrane and the subarachnoid space,
which may impair CSF circulation leading to
hydrocephalus.
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32. Subarachnoid hemorrhage: The blood
is under the arachnoid so it can enter
the sulci
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41. Sample MCQS
• The presence of blood in a spinal tap taken
from an individual with a closed head injury
signals arterial bleeding into the:
• A. Cavernous sinus
• B. Epidural space
• C. Subarachnoid space
• D. Subdural space
• E. Maxillary sinus
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