Neuro-Anatomy
lec: 2 Prof Dr. Al-Hubaity
Tributaries of Cavernons sinus:
1. Central vein of the retina.
2. Opthamic veins (superior one via S.O.F,Inferior one via L.O.F).
3. Sphenoparietal venous sinus.
4. Some veins on the base of the brain.
The cavernous sinus is present on either side of the body of sphenoid
extending from the medial end of S.0.F to the apex of the petrous bone.
The 2 cavernous sinus are connected together by intercavernous sinus.
Drainage (Terminations):
1- Inferior termination to the pterygoid venous plexus in the
infratemporal fossa via foramen lacerum or ovale.
2- Posterior termination to:
Superior petrosal sinus on the upper surface of the petrous
bone, it joins the junction between transverse of sigmoid
sinuses.
Inferior petrosal sinus runs on the petro-occipital groove
(sulcus) to go directly to the jugular foramen.
The inferior petrosal sinuses are connected via basilar renons plexus (on
the basi-occiput). This basilar plexus forms a rout of communication
between the 2 inferior petrosal sinuses from one side and also
communicate with internal vertebral venous plexus via foramen magnum.
The cavernous sinus is liable to infection (from dangerous triangle around
the mouth via the communication of ophthalmic vein and angular of
facial vein) results in cavernous sinus thrombosis leading to pressure on
the cranial nerves supply the extra occnlar muscle which become
paralyzed.
Emissary veins: Valveless veins which connect the dural sinuses inside
the skull with the veins outside the skull. They pass through emissary
foramina in the wall of the skull.
They serve to equalize blood pressure between sinuses and the veins
outside the skull, and may pass along these routes to reach the cranial
cavity.
Some emissary veins has the following connections:
1- Superior sagittal sinus is connected to outside veins via:
Parietal foramen join S.S.S with occipital veins.
Foramen caecum join S.S.S with veins of nose.
2- Sigmoid sinus: by emissary veins pass through :
Mastoid foramen: joins the sius with the occipital veins.
Condylar foramen: with suboccipital venous plexus.
3- With cavernous sinus:
Foramen ovale and lacerum join it with the pterygoid venous
plexus.
Carotid canal joins the sinus with the pharyngeal plexus of
veins.
Ophthalmic veins may be considered as emissary veins.
Relations of cavernous sinuses:
1- Medially by sphenoid air sinuses and pituitary gland.
2- Laterally by trigeminal ganglion and temporal lobe of brain.
Pterion:
Is the site on the side of the skull which represent the meetings of bones
(frontal, parietal, temporal and greater wing of sphenoid). It an important
clinical area of great surgical importance for the following reasons:
1- On its inside surface runs the frontal branch of middle meningeal
artery, thus in any fracture or trauma to the region of pterion, this
artery will tear and lead to accumulation of cloted blood
(extradural or epidural hematoma).
2- It is related to the primary motor area of the cerebral cortex
(precentral gyrus) responsible for the movement of opposite half of
the body except lower limb and half of perineum.
Extradural or epidural hematoma is due to injury to the middle
meningeal artery or any meningeal artery
Subdural hematoma is injury to ameningeal vein or venous sinuses.
Subarachnoid haemorrhage is due to rupture intracerebral
aneurysm or any cerebral artery in the subarachnoid spaces.
Blood supply of meninges:
1- Anterior meningeal branch from anterior ethmoidal.
2- Middles accessory meningeal branch from maxillary artery.
3- Posterior meningeal from many sources as from occipital,vertebral
or ascending pharyngeal.
Nerves of the menings:
1- Meningeal branch of anterior ethmoidal nerve to the floor of
anterior part of falx cerberi and part of tentorium cerehelli.
2- Meningeal branch of maxillary division as for e.g tentorial branch.
3- Meningeal branch of mandibular nerve.
4- Meningeal branch from C1-C3 cervical spinal nerves coming via
foramen magnum, hypoglossal and jugular as for e.g recurrent
meningeal.
Arachnoid matter:
A thin, transparent, avascular membrane lies between dura and pin
matter.
Between it and dura is subdural space.
Between it and pia is subarachnoid space.
The araehnoid sends fine fingers like projections known as villi,
aggregation of the villi forms arachnoid granulation which connects
between subarachnoid spaces and some venous sinuses, usually along the
course of S.S.S and forms a route for the passage of some C.S.F to the
venous blood of the S.S.S.
Pia matter:
A thin vascular membrane. In direct contact and firmly adher to the
surface of the brain and follows into the deepest sulci of the brain it gives:
1- A sleeve covering to the blood vessels entering the brain.
2- Tooth like processes along the side of spinal cord between the root
of spinal nerves known as ligamentum denticnlatum.
3- Filumn terminale which is a tubular like projection of pia from the
lower end of spinal cord to the back of coccyx.