Neuroanatomy

1. Meninges of Brain & Spinal Cord
Dura Venous Sinuses & Clinical Relevance
Dr. Rabia Inam Gandapore
Assistant Professor
Head of Department Anatomy
(Dentistry-BKCD)
B.D.S (SBDC), M.Phil. Anatomy (KMU),
Dip. Implant (Sharjah, Bangkok, ACHERS) , CHPE
(KMU),CHR (KMU), Dip. Arts (Florence, Italy)

2. Teaching Methodology
 LGF (Long Group Format)
 SGF (Short Group Format)
 LGD (Long Group Discussion, Interactive discussion with the use of models or diagrams)
 SGD (Short Group)
 SDL (Self-Directed Learning)
 DSL (Directed-Self Learning)
 PBL (Problem- Based Learning)
 Online Teaching Method
 Role Play
 Demonstrations
 Laboratory
 Museum
 Library (Computed Assisted Learning or E-Learning)
 Assignments
 Video tutorial method

3. Goal/Aim (main objective)
 To help/facilitate/augment the students about the:
1. Explain structural features, blood & nerve supply of meninges.
2. Enumerate relevant clinical problems of structures of cranial cavity (e.g.,
headache, extradural and subdural hemorrhage etc.).
3. Enlist paired and unpaired venous sinuses of dura matter.
4. Identify various folds of the dura mater on a model
5. Describe relations, tributaries, and drainage of venous sinuses
6. Enumerate relevant clinical problems of venous sinuses (e.g., thrombosis of
cavernous sinus, sigmoid and super sagittal sinus pulsating exophthalmos etc.).
7. Relate connection of emissary veins with sinuses.

4. Specific Learning Objectives (cognitive)
At the end of the lecture the student will able to:
 Explain structural features, blood & nerve supply of meninges.
 Enumerate relevant clinical problems of structures of cranial cavity.
 Describe relations, tributaries, and drainage and clinical problems of
venous sinuses
 Relate connection of emissary veins with sinuses.
 Sketch labeled diagram of Dura venous Sinuses.

5. Psychomotor Objective: (Guided response)
 A student to draw labelled diagram of Dura venous sinuses

6. Affective domain
 To be able to display a good code of conduct and moral values in the class.
 To cooperate with the teacher and in groups with the colleagues.
 To demonstrate a responsible behavior in the class and be punctual, regular, attentive and on time in the class.
 To be able to perform well in the class under the guidance and supervision of the teacher.
 Study the topic before entering the class.
 Discuss among colleagues the topic under discussion in SGDs.
 Participate in group activities and museum classes and follow the rules.
 Volunteer to participate in psychomotor activities.
 Listen to the teacher's instructions carefully and follow the guidelines.
 Ask questions in the class by raising hand and avoid creating a disturbance.
 To be able to submit all assignments on time and get your sketch logbooks checked.

7. Lesson contents
Clinical chair side question: Students will be asked if they know what is the function of
Outline:
 Activity 1 The facilitator will explain the student's about Meninges of brain & spinal cord
 Activity 2 The facilitator will ask the students to make a labeled diagram of dura venous sinuses
 Activity 3 The facilitator will ask the students a few Multiple Choice Questions related to it with flashcards.

8. Recommendations
 Students assessment: MCQs, Flashcards, Diagrams labeling.
 Learning resources: Langman’s T.W. Sadler, Laiq Hussain Siddiqui, Snell Clinical Anatomy, Netter’s Atlas,
BD Chaurasia’s Human anatomy, Internet sources links.

9. Meninges of Brain
 Brain in skull & spinal cord in vertebral
column are surrounded by 3 protective
membranes, or meninges:
1. Dura mater
2. Arachnoid mater
3. Pia mater.

10. 1.Dura Mater
 Outer toughest layer & protect underlying nervous tissue, cranial
nerves by forming a sheath covering. It provides spinal nerve
root with protection.
 It has two layers & are united except, where they separate to
form venous sinuses:
A. Endosteal layer: periosteum covering inner surface of skull
 At foramen magnum, it does not become continuous with dura
mater of spinal cord.
 Around margins of foramina in skull, its continuous with
periosteum on outside of skull bones.
 At sutures: continuous with sutural ligaments.
 Base of skull Bones: strongly adherent

13. B. Meningeal layer
 is dura mater proper.
 Dense, strong fibrous membrane covering brain & is continuous through foramen
magnum with dura mater of spinal cord.
 Provides tubular sheaths for cranial nerves as they pass through foramina in skull.
 Outside skull, sheaths fuse with epineurium of nerves.
 This layer sends inward 4 septa (Falx cerebri , Tentorium Cerebelli, Falx
Cerebelli) which divide cranial cavity into freely communicating spaces that lodge
subdivisions of brain.
 Function of septa is to restrict displacement of brain associated with acceleration &
deceleration, when head is moved.

15. a.Falx cerebri
 Sickle-shaped fold of dura mater that lies in midline between two cerebral
hemispheres & serve to limit excessive movements of brain within skull.
 Narrow anterior end: attached to internal frontal crest & crista galli.
 Broad posterior part: blends in midline with upper surface of tentorium cerebelli.
 Superior sagittal sinus runs in its upper fixed margin
 Inferior sagittal sinus runs in its lower concave free margin
 Straight sinus runs along its attachment to tentorium cerebelli.

19. b.Tentorium Cerebelli
 Crescent-shaped fold of dura mater that roofs over posterior cranial fossa.
 Covers upper surface of cerebellum & supports occipital lobes. It limits excessive
movements of brain within skull.
 In anterior edge there is a gap ”tentorial notch”, for passage of midbrain, which
produces:
a. Outer Fixed border is attached to posterior clinoid processes,superior borders of
petrous bones & margins of grooves for transverse sinuses on occipital bone.
b. Inner Free border runs forward at its two ends, crosses the attached border & is
affixed to anterior clinoid process on each side.
 At the point where two borders cross, oculomotor & Trochlear nerves pass forward
to enter lateral wall of cavernous sinus.

23.  Close to apex of petrous part of temporal bone,
lower layer of tentorium is pouched forward
beneath superior petrosal sinus to form a
recess for trigeminal nerve & ganglion.
 Falx cerebri & falx cerebelli are attached to
upper & lower surfaces of tentorium,
respectively.
 Straight sinus runs along its attachment to falx
cerebri,
 Superior petrosal sinus runs along its
attachment to petrous bone
 Transverse sinus runs along its attachment to
occipital bone.

27. c. Falx cerebelli
 Small, sickle-shaped fold of dura mater
attached to the internal occipital crest,
projects forward between 2 cerebellar
hemispheres.
 Its posterior fixed margin contains occipital
sinus.
 Diaphragma sellae is a small, circular fold
of dura mater that forms the roof for sella
turcica.
 A small opening in its center allows passage
of stalk of hypophysis cerebri.

29. Dural Nerve Supply
 Branches of trigeminal, vagus, & first three cervical
spinal nerves & branches from sympathetic trunk
pass to dura.
 Dura possesses numerous sensory endings for
stretching, which cause sensation of headache.
1. Stimulation of sensory endings of trigeminal nerve
above level of tentorium cerebelli produces referred
pain to skin on ipsilateral head.
2. Stimulation of dural endings below level of tentorium
produces pain referred to back of neck & scalp along
distribution of greater occipital nerve.

30. Dural Arterial Supply
 Arteries: froms internal carotid, maxillary, ascending pharyngeal, occipital, & vertebral arteries.
 Most important= Middle meningeal artery: can be damaged in head injuries
Arises: from maxillary artery in infratemporal fossa
Enters: cranial cavity through foramen spinosum & then lies between meningeal and endosteal layers
of dura. It runs forward & laterally in a groove on upper surface of squamous part of temporal bone.
Branches:
1. Anterior branch: deeply grooves or tunnels the anterior-inferior angle of parietal bone & its course
corresponds roughly to line of underlying precentral gyrus of brain.
2. Posterior branch: curves backward & supplies posterior part of dura mater.
 Veins: lie lateral to arteries.
Meningeal veins: lie in endosteal layer of dura & follows branches of middle meningeal artery & drains
into pterygoid venous plexus or sphenoparietal sinus.

34. Dural Venous Sinuses

35. Dural Venous Sinuses
 Situated between layers of dura mater.
 Function: receive blood from brain through cerebral veins & cerebrospinal fluid from
subarachnoid space through the arachnoid villi.
 Blood in dural sinuses ultimately drains into internal jugular veins in neck.
 Dural sinuses are lined by endothelium & walls are thick but devoid of muscular tissue.
 No valves.
 Emissary veins: valveless, connect dural venous sinuses with diploic veins of skull
& with veins of scalp. It connect the extracranial venous system with the intracranial
venous sinuses, allowing for communication between the two systems. These veins
can provide a route for the spread of infection or tumors between the scalp and the
brain.

38. Superior sagittal sinus
 occupies upper fixed border of falx cerebri.
 Begins: anteriorly at foramen cecum & receives vein from nasal cavity. It runs
posteriorly, grooving vault of skull; at internal occipital protuberance, it deviates to one
or other side (usually right) & becomes continuous with transverse sinus.
 It communicates through small openings with 2 or 3 irregularly shaped venous
lacunae on each side.
 Arachnoid villi & granulations project into lacunae & receive diploic & meningeal veins.
 Superior sagittal sinus receives superior cerebral veins.
 At internal occipital protuberance, its dilated to form confluence of the sinuses & is
continuous with right transverse sinus; its connected to opposite transverse sinus &
receives occipital sinus.

39. Paired:
Superior sagittal sinus
Transverse sinus
Sigmoid sinus
Cavernous sinus.
Unpaired:
Straight sinus
Occipital sinus.

43. Inferior sagittal sinus
 Occupies free lower margin of falx
cerebri.
 Runs backward & joins great
cerebral vein at free margin of
tentorium cerebelli to form the
straight sinus.
 It receives a few cerebral veins from
medial surface of cerebral
hemispheres.

45. Straight sinus
 occupies line of junction of falx
cerebri with tentorium cerebelli.
 Its formed by union of inferior sagittal
sinus with great cerebral vein.
 It ends by turning to the left
(sometimes to the right) to form the
transverse sinus.

46. Transverse sinuses
 Paired structures that begin at internal occipital
protuberance.
 Right sinus continuous with superior sagittal sinus
 Left sinus continuous with straight sinus.
 Each sinus occupies the attached margin of tentorium
cerebelli, grooving occipital bone & posteroinferior
angle of parietal bone.
 It receive superior petrosal sinuses, inferior
cerebral & cerebellar veins & diploic veins.
 They end by turning downward as sigmoid sinuses .

48. Sigmoid sinuses
 Are direct continuation of transverse
sinuses.
 Each sinus turns downward & medially &
grooves mastoid part of temporal bone.
 It is here sinus lies posterior to mastoid
antrum.
 Sinus then turns forward & then inferiorly
through posterior part of jugular foramen to
become continuous with the superior bulb
of internal jugular vein.

52. Occipital sinus
 Small sinus occupying the
attached margin of falx cerebelli.
 It commences near foramen
magnum, where it communicates
with the vertebral veins & drains
into confluence of sinuses.

54. Cavernous sinuses
 Situated in the middle cranial fossa on each side of body
of sphenoid bone.
 Numerous trabeculae cross their interior, giving them a
spongy appearance, hence the name.
 Each sinus extends from superior orbital fissure in front to
the apex of petrous part of temporal bone behind.
 Internal carotid artery: Surrounded by its sympathetic
nerve plexus, runs forward through the sinus.
 Abducent nerve also passes through it.
 Internal carotid artery & nerves are separated from blood by
endothelial covering.

58.  3rd & 4th cranial nerves, ophthalmic & maxillary
divisions of trigeminal nerve run forward in
lateral wall of sinus.
 They lie between the endothelial lining & dura
mater.
 Tributaries are:
Superior ophthalmic veins
Inferior ophthalmic veins
Inferior cerebral veins
Sphenoparietal sinus
Central vein of retina.
 Sinus drains:
Posteriorly: into superior & inferior petrosal
sinuses
Inferiorly: into pterygoid venous plexus.

63. Intercavernous sinuses
 Two sinuses communicate with each other
by means of anterior & posterior
intercavernous sinuses, which run in
diaphragma sellae anterior & posterior to
stalk of hypophysis cerebri.
 Each sinus has an important
communication with facial vein through the
superior ophthalmic vein. (route via
infection can travel from facial skin to
cavernous sinus.

66. Superior & inferior Petrosal sinuses
 Small sinuses situated on superior &
inferior borders of the petrous part of
temporal bone on each side of skull.
 Each superior sinus drains cavernous
sinus into transverse sinus
 Each inferior sinus drains cavernous
sinus into internal jugular vein.

67. 2. Arachnoid Mater
 Delicate, impermeable membrane covering brain
 Lying between pia mater internally & dura mater externally.
 Its separated from dura by subdural space, filled by film of fluid
 Separated from pia by subarachnoid space, filled with CSF.
 Outer & inner surfaces of arachnoid are covered with flattened mesothelial cells.
 Arachnoid bridges over sulci on surface of brain & arachnoid and pia are separated to form subarachnoid
cisternae.
1. Cisterna cerebellomedullaris lies between inferior surface of cerebellum & roof of 4th ventricle.
2. Cisterna interpeduncularis lies between two cerebral peduncles.
 All cisternae are in free communication with one another & with remainder of subarachnoid space.
 Arachnoid projects into venous sinuses to form arachnoid villi & numerous along superior sagittal sinus.
 Aggregations of arachnoid villi are called arachnoid granulations.
 Arachnoid villi serve as sites where CSF diffuses into bloodstream.

69.  Arachnoid is connected to pia mater across fluid-filled subarachnoid space by
delicate strands of fibrous tissue.
 Structures passing to & from the brain to skull or foramina must pass through
subarachnoid space & all cerebral arteries, veins & cranial nerves lie it
 Arachnoid fuses with epineurium of nerves at their point of exit from skull.
 In optic nerve, arachnoid forms a sheath for nerve, which extends into orbital
cavity through optic canal & fuses with sclera of eyeball.Hence, subarachnoid
space extends around optic nerve as far as eyeball.
 CSF is produced by choroid plexuses within lateral, 3rd & 4th ventricles of brain
& escapes from ventricular system of brain through 3 foramina in roof of 4th
ventricle & enters subarachnoid space. It circulates both upward over surfaces
of cerebral hemispheres & downward around spinal cord. Spinal subarachnoid
space extends down upto S2 vertebra. CSF enters bloodstream by passing into
arachnoid villi & diffusing through their walls.
 CSF removes waste products associated with neuronal activity & provides a
fluid medium in which brain floats. It protects brain from trauma. It play a role in
hormonal transport.

71. 3. Pia Mater
 Vascular membrane covered by flattened
mesothelial cells.
 Supports: brain & spinal cord.
 Invests brain, covering gyri & descending
into deepest sulci.
 Extends over cranial nerves & fuses with
epineurium.
 Cerebral arteries entering substance of
brain carry a sheath of pia with them.
 Pia mater forms tela choroidea of roof of
3rd & 4th ventricles of brain & it fuses with
ependyma to form choroid plexuses in
lateral, 3rd & 4th ventricles of brain.

73. Meninges of Spinal Cord

74. 1. Dura Mater
 Dense, strong, fibrous membrane that encloses spinal cord & cauda equina.
 Its continuous above through foramen magnum with meningeal layer of dura
covering brain.
 Inferiorly: it ends on filum terminale at level of lower border of S2 vertebra.
 Dural sheath lies loosely in vertebral canal & is separated from the wall of canal
by extradural space.
 It contains loose areolar tissue & internal vertebral venous plexus.
 It extends along each nerve root & becomes continuous with the connective tissue
surrounding each spinal nerve (epineurium).
 Inner surface of dura mater is in contact with arachnoid mater.

80. 2. Arachnoid Mater
 Delicate impermeable membrane that covers spinal cord
 Lies between pia mater internally & dura mater externally.
 Its separated from pia mater by subarachnoid space filled with CSF & is
crossed by a number of fine strands of connective tissue.
 Its continuous above through foramen magnum with arachnoid covering brain.
 Inferiorly, it ends on filum terminale at level of lower border of S2 vertebra.
 It continues along spinal nerve roots, forming small lateral extensions of
subarachnoid space.

82. 3. Pia Mater
 Vascular membrane that closely covers
spinal cord is thickened on either side
between the nerve roots to form the
ligamentum denticulatum, which passes
laterally to adhere to arachnoid & dura.
 Via this spinal cord is suspended in middle
of dural sheath.
 It extends along each nerve root & becomes
continuous with the connective tissue
surrounding each spinal nerve.

86. Clinical Relevance

87. Excessive Movements of Brain Relative to
Skull & Meninges in Head Injuries
 Moving patient's head is suddenly halted, momentum of brain causes it to travel onward until
its movement is resisted by skull or strong septa of dura mater.
 Lateral movements: lateral surface of one hemisphere hits side of skull & medial surface of
opposite hemisphere hits side of falx cerebri.
 Superior movements: superior surfaces of cerebral hemispheres hit vault of skull & superior
surface of corpus callosum hits sharp free edge of falx cerebri; superior surface of cerebellum
presses against the inferior surface of tentorium cerebelli.
 Movements of brain relative to skull & dural septa injure the cranial nerves & Fragile cortical
veins that drain into dural sinuses torns, resulting in severe subdural or subarachnoid
hemorrhage. Arteries (strong walls) rarely damaged.

88. Intracranial Hemorrhage &
Meninges
1. Epidural Hemorrhage: results from injuries to meningeal arteries or veins.
 Middle Meningeal Artery (anterior division): most common damaged at pterion suture
 Bleeding occurs & strips up meningeal layer of dura from internal surface of skull.
 Intracranial pressure rises & enlarging blood clot exerts local pressure on underlying motor
area in the precentral gyrus. (Lucid interval)
 Blood also passes laterally through the fracture line to form a soft swelling under temporalis
muscle. To stop hemorrhage, torn artery or vein must be ligated or plugged.
 Burr hole through skull wall should be placed about 1-1/2 inches (4 cm) above the midpoint of
zygomatic arch.

90. Computed Tomography Scans of
Epidural & Subdural Hematomas
 blood clots seen on CT scans
 Epidural hemorrhage, blood strips
up meningeal layer from endosteal
layer of dura (periosteum of skull),
producing a lens-shaped hyper
dense collection of blood that
compresses brain & displaces
midline structures to opposite side.
The shape of blood clot is
determined by the adherence of
meningeal layer of dura to periosteal
layer of dura.

91. 2. Subdural Hemorrhage
 Results from tearing of superior cerebral
veins at point of entrance into superior
sagittal sinus.
 Cause: blow on front or back of head,
causing excessive antero-posterior
displacement of brain within skull.
 Acute & chronic forms of condition occur

92.  Subdural hematoma, blood accumulates in extensive potential space between
meningeal layer of dura & arachnoid, producing a long crescent-shaped, hyper dense
rim of blood that extends from anterior to posterior along the inner surface of skull.
With a large hematoma, brain sulci are obliterated & midline structures are displaced
to opposite side.

93. Intracranial Hemorrhage in Infant
 Intracranial hemorrhage may occur during birth &
result from excessive molding of head.
 Bleeding may occur from cerebral veins or
venous sinuses.
 Excessive anteroposterior compression of head
often tears anterior attachment of falx cerebri from
tentorium cerebelli.
 Bleeding then takes place from great cerebral
veins, straight sinus or inferior sagittal sinus
(shaken-baby syndrome).

94. Headache
 Brain is insensitive to pain
 Headaches Due to stimulation of receptors outside
brain

95. Meningeal Headaches
 Dura mater receives its sensory nerve supply from
trigeminal & first three cervical nerves.
 Dura above tentorium: innervated by trigeminal
nerve & headacheis referred to forehead & face.
 Dura below tentorium: innervated by cervical
nerves & headache is referred to back of head &
neck.
 Meningitis, or inflammation of meninges: causes
severe headache over entire head & back of neck.

96. Headaches Caused by Cerebral Tumors
 Expanding tumor & raised intracranial
pressure produces severe, continuous &
progressive headache caused by
irritation & stretching of dura.
 Tumor above tentorium: produce a
headache referred to front of head
 Tumor below tentorium: produces a
headache referred to back of head.

97. Migraine Headache
 Common, can be unilateral or bilateral, recurring at intervals
& associated with prodromal visual disturbances.
 Prodromal visual disturbances are thought to be due to
sympathetic vasoconstriction of cerebral arteries supplying
visual cortex.
 Dilatation & stretching of other cerebral arteries & branches
of external carotid artery & affect arteries both inside &
outside skull & cause is unknown, although genetic,
hormonal & biochemical factors may initiate an attack.
 beta-blockers bring relief due to reduction in cerebral
vasodilation.

98. Alcoholic Headache
 Due to direct toxic effect of alcohol
on meninges.

99. Headaches Due to Diseases of Teeth,
Paranasal Sinuses & Eyes
 Dental infection & sinusitis are common
causes of headache. Pain is referred to
skin of face & forehead along the
branches of trigeminal nerve.
 Tonic spasm of ciliary muscle of eye,
when attempting to focus on an object
for prolonged periods (e.g., reading
small print), may cause severe orbital
headache & commonly occurs in
individuals who need lenses for
correction of presbyopia

100. Clinical Problems of Venous Sinuses
Thrombosis of cavernous sinus
 Pulsating exophthalmos (protrusion of the
eyeball) due to thrombosis or increased
pressure in the cavernous sinus or superior
sagittal sinus.

101. Thank You
ANY QUESTIONS?