DURAL FOLDS AND CAVERNOUS SINUS

M.ARAVIND

MENINGES The interior of the cranial

cavity is lined by the durameter.

The surface of the brain is covered by the piameter.

The dura is separated from the arachnoid by subdural space.

The arachnoid is separated from the pia by subarachnoid space. (CSF)

Between these two lies the arachnoid mater.

These three together constitute the meninges of the brain.

DURAMATER The cerebral duramater

consisting of the outermost thickest and toughest membrane consisting of two layers.

Outer endosteal layer (endocranium) periosteum lining the inner surfaces of the skull bones.

Inner meningeal layer (duramater proper) encloses the brain and at the foramen magnum becomes continuous with the duramater surrounding the spinal cord.

DURAL FOLDS At places, the

meningeal layer is folded on itself to form dural folds(dural septa).

Falx cerebri Tentorium cerebelli Falx cerebelli Diaphragma sella

Falx cerebri Tentorium cerebelli

Falx cerebelli Diaphragma sella

Shape & location

Large sickle shapedMedian longitudinal fissure

Tent shapedCerebellum & occipital lobes

Sickle shapedPosterior cerebellar notch

Small circularRoof of the hypophyseal fossa

Attachments

Crista galliMedian plane of upper surface of tentorium cerebelli

Transverse sulcusPetrous temporal bone, post. Clinoid process

Inf surface of tentorium cerebelli on median plane

Tuberculum sellae, dorsum sellae Dura middle cranial fossa

Margins

Upper-Convex saggital sulcusLower-Concave free

U-shaped ant free margin ant clinoid process. bears tentorial notch

Apex -foramen magnumconvex-internal occipital crest

--------

Surface

Medial surface of cerebral hemisphere

Superiorly –occipital lobe of cerebrum inferiorly-superior cerebellum

------- hypophysis cerebri

Sinus Superior & inferior saggitalStraight sinus

TransverseSuperior petrosal

Occippital ---------

TRIGEMINAL OR MECKEL’S CAVE It is a recess of the dura

mater present in relation to the attached outer margin of the tentorium cerebelli

It is formed by the evagination of the meningeal layer of duramater by two roots of the trigeminal nerve below the superior petrosal sinus over the trigeminal impression on the anterior surface of the petrous temporal bone near its apex

BLOOD SUPPLY OF DURA

The vault- supplied by middle meningeal artery

The anterior cranial fossa and the dural lining- supplied by anterior ethmoidal, posterior ethmoidal and ophthalmic arteries

The middle cranial fossa- supplied by middle meningeal arteries, accessory meningeal and internal carotid arteries, and meningeal branches of ascending pharyngeal artery.

The posterior cranial fossa- supplied by meningeal branches of vertebral, occipital and ascending pharyngeal arteries

NERVE SUPPLY OF DURA The dura of the vault is supplied by sensory nerves

derived from ophthalmic division of trigeminal nerve The dura of the floor has rich nerve supply and is

sensitive to pain:

- anterior cranial fossa- supplied by anterior ethmoidal nerve and partly by maxillary nerve

- middle cranial fossa- supplied by maxillary nerve in the anterior part and by branches of mandibular nerve and from the trigeminal ganglion in the posterior part

- posterior cranial fossa- supplied by recurrent branches of 1st, 2nd and 3rd cervical spinal nerves and by meningeal branches of 9th and 10th cranial nerves

CLINICAL ANATOMY EXTRA DURAL AND SUBDURAL HAEMORRHAGES Common Distinguished by Extradural Haemorrhage is arterial (injury to middle

meningeal artery) Subdural Haemorrhage- venous Extradural Haemorrhage - symptoms of cerebral

compression are late Extradural Haemorrhage- paralysis appears first in

the face and then spreads to lower parts of the body. Subdural Haemorrhage - haphazard

Extradural Haemorrhage- no blood in the CSF. - Subdural Haemorrhage- it is a common feature.

CAVERNOUS SINUS Large venous space Situation- Middle cranial fossa on

either side of body of sphenoid bone Divided into caverns (spaces) by

trabeculae (prominent in dead) Floor & medial wall – endosteal

duramater Lateral wall & roof – meningeal

duramater

EXTENSION Anteriorly- superior orbital fissure Posteriorly- apex of petrous temporal

bone 2cm long, 1cm wide

RELATIONS SUPERIORLY

Optic chiasma Optic tract Olfactory tract Internal carotid artery INFERIORLY Foramen lacerum Junction of the body and the

greater wing of sphenoid MEDIALLY Hypophysis cerebri Sphenoidal air sinus

LATERALLY Temporal lobe with

uncus BELOW LATERALLY Mandibular nerve ANTERIORLY Superior orbital fissure Apex of the orbit POSTERIORLY Apex of the petrous

temporal bone Crus cerebri of mid

brain

TRIBUTARIESFROM THE ORBIT Superior ophthalmic vein Inferior ophthalmic vein Central vein of retina

FROM THE BRAIN Superficial middle cerebral

vein Inferior cerebral vein

FROM THE MENINGES Sphenoparietal sinus Frontal trunk of middle

meningeal vein

STRUCTURES PASSING THROUGH

LATERAL WALL Occulomotor Trochlear Ophthalmic maxillary

MEDIAL WALL Internal carotid artery Abducent nerve

COMMUNICATIONS With transverse sinus - via superior petrosal

sinus With internal jugular vein – through inferior

petrosal sinus and a plexus of veins around internal carotid artery

With pterygoid venous plexus – through emissary veins passing through foramen ovale, emissary sphenoidal foramen and foramen lacerum

With opposite cavernous sinus- via anterior and posterior intercavernous sinus

With facial vein by two routes-

- Superior ophthalmic vein and angular vein

- Pterygoid venous plexus and deep facial vein

CAVERNOUS SINUS THROMBOSIS

Septic thrombosis of cavernous sinus -by communication from dangerous area of face, orbit and pharynx

-severe pain in eye and forehead

-ophthalmoplegia due to involvement of 3rd , 4th and 6th cranial nerves

- Marked oedema of eyelids

- exophthalmos

PULSATING EXOPHTHALMOS

Pulsating exophthalmos- internal carotid artery is ruptured as a result of fracture of base of skull – arterio- venous communication is established

- ligation of inernal carotid artery may be helpful, but patient may develop contralateral hemiplegia