Transcript The skull & foramina

DURAL VENOUS SINUSES
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The venous sinuses…
• The venous sinuses of the cranial cavity are blood-filled
spaces situated between the layers of the dura mater
they are lined by endothelium. Their walls are thick and
composed of fibrous tissue; they have no muscular
tissue. The sinuses have no valves.
• Absorb the C.S.F through the arachnoid granulation
tissue & Receive blood from valveless emissary
veins
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Classification of Dural sinuses:
The venous sinuses are classified into paired and unpaired
groups:
Unpaired sinuses:
1. Superior sagittal sinus
2. Inferior sagittal sinus
3. Straight sinus
4. Occipital sinus
5. Anterior intercavernous sinus
6. Posterior intercavernous sinus
7. Basilar venous plexus
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Paired sinuses:
1. Transverse
2. Sigmoid sinus
3. Cavernous sinus
4. Superior petrosal sinus
5. Inferior petrosal sinus
6. Spheno-parietal sinus
7. Petro-squamous
8. Middle meningeal
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Superior sagittal sinus
• The superior sagittal sinus lies in the upper fixed
border of the falx cerebri. It runs backward and
becomes continuous with the right transverse
sinus.
• The sinus communicates on each side with the
venous lacunae. Numerous arachnoid villi and
granulations project into the lacunae. The
superior sagittal sinus receives the superior
cerebral veins.
 On rare occasion it receives a vein from nasal
cavity through patent foramen caecum
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Superior sagittal sinus…
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Applied anatomy:
Thrombosis
of
the
superior sagittal sinus
may take place due to
spread
of
infection
from the nose, scalp
and diploic tissue
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The inferior sagittal sinus
• The inferior sagittal sinus lies in the free lower margin
of the falx cerebri. It runs backward and joins the
great cerebral vein to form the straight sinus. It
receives cerebral veins from the medial surface of the
cerebral hemisphere
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The straight sinus
• The straight sinus, also known as tentorial sinusi it
receives blood from the superior cerebellar veins and
inferior sagittal sinus and drains into the confluence of
sinuses
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The transverse sinuses
• The transverse sinuses (left and right lateral
sinuses), within the human head, are two
areas beneath the brain which allow blood to
drain from the back of the head.
• They run laterally in a groove along the interior
surface of the occipital bone. They drain from
the confluence of sinuses (by the internal
occipital protuberance) to the sigmoid
sinuses, which ultimately connect to the
internal jugular vein.
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The sigmoid sinuses
• The sigmoid sinuses, also known as the pars sigmoid,
are venous sinuses within the skull that receive blood
from posterior dural venous sinus veins.
• Each sinus turns downward behind the mastoid antrum
of the temporal bone and then leaves the skull through
the jugular foramen to become the internal jugular vein
Applied anatomy:
 Thrombosis of sigmoid sinus may take place from the
infected middle ear or mastoid antrum
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The occipital sinus
• The occipital sinus lies in the attached margin of the
falx cerebelli. It communicates with the vertebral veins
through the foramen magnum and the transverse sinuses
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The cavernous sinus
• Each cavernous sinus lies on the lateral side of the
body of the sphenoid bone. Anteriorly, the sinus
receives the inferior ophthalmic vein and the central
vein of the retina. The sinus drains posteriorly into the
transverse sinus through the superior petrosal sinus.
Intercavernous sinuses connect the two cavernous
sinuses through the sella turcica
• Important Structures Associated With the Cavernous
Sinuses :The internal carotid artery and the sixth
cranial nerve, which travel through it
• In the lateral wall, the third and fourth cranial nerves,
and the ophthalmic and maxillary divisions of the fifth
cranial nerve. The pituitary gland, which lies medially in
the sella turcica.
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Anterior and posterior intercavernous sinus:
Each sinus traverse respectively along the anterior and posterior
attached margin of diaphragma sellae and connects the
cavernous sinus of both side
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Basilar venous plexus:
It is a plexiform venous network and lies on the clivus of the
skull
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Applied anatomy:
The veins of the face, which are connected with the cavernous sinus
via the facial vein and inferior ophthalmic vein, and are an important
route for the spread of infection from the face
The superior and inferior petrosal sinuses, which run along the upper
and lower borders of the petrous part of the temporal bone
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Superior petrosal sinus sinus:
 Conveys the blood from the cavernous sinus to the transverse
sinuses
 It is situated in lateral attached border of tentorium cerebelli
Tributaries:
 Inferior cerebral veins
 Some cerebellar veins
 Veins from the tympanic cavity
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Inferior petrosal sinus:
Drains the blood from cavernous sinus into the superior bulb of
internal jugular vein
Tributaries:
 Labyrinthine veins from
the cochlear cannaliculi
and aqueduct of vestibule
 Veins from the medulla,
pons and cerebellum
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Applied anatomy:
Thrombosis of inferior petrosal sinus may occur from the infection
of middle and internal ear, with ipsilateral involvement of trigeminal
and abducent nerves
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The skull & foramina
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Cranial foramina
• The human skull has numerous holes
(foramina) through which cranial nerves,
arteries, veins and other structures pass.
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Cranial foramina…
• Frontal bone - supraorbital foramen
1. supraorbital artery,
2. supraorbital vein
3. supraorbital nerve
• foramen cecum
1. emissary veins to superior sagittal sinus
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Cranial foramina…
• Ethmoid bone - foramina of cribriform plate –
1. olfactory nerve bundles (I)
• anterior ethmoidal foramen
1. anterior ethmoidal artery
2. anterior ethmoidal vein
3. anterior ethmoidal nerve
• posterior ethmoidal foramen
1. posterior ethmoidal artery
2. posterior ethmoidal vein
3. posterior ethmoidal nerve
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Cranial foramina…
• Optic canal
1. Ophthalmic artery optic nerve (II)
• superior orbital fissure
1. superior ophthalmic vein
2. oculomotor nerve (III)
3. trochlear nerve (IV)
4. lacrimal, frontal and nasociliary branches of
ophthalmic nerve (V1)
5. abducent nerve (VI) sphenoid middle cranial
fossa
foramen rotundum - maxillary nerve (V2) maxilla
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Cranial foramina…
• Incisive foramen/incisive canal
1. sphenopalatine artery
2. nasopalatine nerve(V2) palatine
• greater palatine foramen
1. greater palatine artery
2. greater palatine vein
3. greater palatine nerve palatine
• lesser palatine foramina
1. lesser palatine artery
2. lesser palatine vein
3. lesser palatine nerve sphenoid and maxilla
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Cranial foramina…
• Inferior orbital fissure
1. inferior ophthalmic veins
2. infraorbital artery
3. infraorbital vein
4. zygomatic nerve and infraorbital nerve of
maxillary
nerve
(V2)
orbital branches of pterygopalatine ganglion
• Infraorbital foramen
1. infraorbital artery
2. infraorbital vein
3. infraorbital nerve
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Cranial foramina…
• foramen ovale
1. mandibular nerve
2. accessory meningeal artery (V3)
3. lesser petrosal nerve (occasionally)
• foramen spinosum
1. middle meningeal artery
2. meningeal branch of the mandibular nerve (V3)
• foramen lacerum
1. artery of pterygoid canal
2. nerve of pterygoid canal
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Cranial foramina…
• Internal acoustic meatus
1. labyrinthine artery
2. facial nerve (VII),
3. vestibulocochlear nerve (VIII)
• Jugular foramen
1. internal jugular vein,
2. inferior petrosal sinus,
3. sigmoid sinus
4. glossopharyngeal nerve (IX),
5. vagus nerve (X),
6. accessory nerve (XI)
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Cranial foramina…
• Hypoglossal canal –
1. hypoglossal nerve (XII)
• Foramen magnum
1. anterior and posterior spinal arteries,
2. vertebral arteries
3. medulla oblongata,
4. ascending spinal fibers of accessory nerve
(XI)
• Stylomastoid foramen
1. stylomastoid artery facial nerve (VII)
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