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Anatomy of cerebral veins and sinuses

Created 09/04/2021, last revision 18/11/2023

Classification

venous blood is drained from the brain by a system of cerebral veins (vv. cerebri), which are emptied into dural sinuses and cervical veins (internal jugular veins and vertebral veins)

Cerebral veins	deep cerebral veins thalamostriate veins choroid veins veins of the septum pellucidum internal cerebral veins great cerebral vein (of Galen) superficial cerebral veins superior superficial cerebral veins middle superficial cerebral veins inferior superficial cerebral veins superior cerebellar veins inferior cerebellar veins
Dural venous sinuses (dural sinuses, cerebral sinuses)	unpaired superior sagittal sinus inferior sagittal sinus straight sinus occipital sinus paired transverse sinus sigmoid sinus superior petrosal sinus inferior petrosal sinus cavernous sinus sphenoparietal sinus basilar venous plexus
Meningeal veins
Ophthalmic veins	superior ophthalmic vein inferior ophthalmic vein
Diploic veins	frontal diploic vein anterior temporal diploic vein posterior temporal diploic vein occipital diploic vein
Emissary veins	frontal emissary vein condylar emissary veins mastoid emissary vein occipital emissary vein parietal emissary vein
Veins of labyrinth

The cerebral veins

cerebral veins drain blood from the brain parenchyma to the dural venous sinuses
veins are characterized by a larger caliber than the cerebral arteries, have thin walls, and lack muscular tissue and valves
typically, they have a variable course and numerous anastomoses
cerebral veins can be divided into:
- superficial (cortical) cerebral veins → draining to the superior sagittal sinus (sinus sagittalis superior)
- deep (subependymal) cerebral veins → draining to the straight sinus (sinus rectus)

Superficial (cortical) cerebral veins

superior cerebral veins
- collect blood from the brain convexity and medial surfaces and drain into the superior sagittal sinus
middle cerebral veins – the most important is the superficial middle cerebral vein (Sylvian vein)
- usually courses along the Sylvian fissure and receives numerous small tributaries from the opercular areas. It curves anteriorly and empties either into the sphenoparietal sinus or directly into the cavernous sinus
- has anastomoses with:
  - the deep middle cerebral vein
  - the superior sagittal sinus (superior anastomotic vein – vein of Trolard). This vein is usually smaller than the superficial middle cerebral vein and vein of Labbé
  - the anterolateral portion of the transverse sinus (inferior anastomotic vein – vein of Labbé)
inferior cerebral veins
- collect blood from the basal parts of the frontal, temporal, and occipital lobes
- drain into the superficial middle cerebral vein, cavernous sinus, superior petrosal sinus, transverse sinus, and some drain into the inferior sagittal sinus

Deep cerebral veins

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Other intracranial veins

meningeal veins
- structures that drain blood from the meninges and underlying cortical regions of the brain
- at the inferior margin, the meningeal veins drain into the large dural sinuses, while at the superior margin, they drain into venous lacunae and the superior sagittal sinus
diploic veins
- large, valveless veins with a thin vascular wall situated in the diploe between the inner and outer layers of the cranial bones
- they connect intracranial venous structures and the surface of the skull; diploic veins are connected with the cerebral sinuses by emissary veins
- subtypes include frontal diploic vein, anterior temporal diploic vein, posterior temporal diploic vein, occipital diploic vein
emissary (skull) veins (vena emissaria)
- frontal, condylar, mastoid, occipital, and parietal emissary veins pass through foramina in the skull to provide a venous communication between the dural venous sinuses and veins of the scalp or veins inferior to the skull base (cranial-cerebral anastomosis)
- they serve as a route for infections between extracranial and intracranial spaces or collateral pathways in case of venous sinus occlusion
ophthalmic veins
- ophthalmic veins (superior, inferior) connect the facial veins with the cavernous sinus

cerebellar veins
- superior cerebellar veins are formed by the union of the precentral cerebellar vein and superior vermian vein. They collect blood from the upper surface of the cerebellum and drain into the great vein (or into the straight, transverse sinus or superior petrosal venous sinuses).
- inferior cerebellar veins collect blood from the inferior surface of the cerebellum and drain into the transverse, occipital, or sigmoid sinuses

brainstem veins
- brainstem veins drain the medulla, pons, and mesencephalon, including the cerebral peduncles, tegmentum, and quadrigeminal plate
- there are multiple connections into the inferior and superior petrosal sinuses, to the basal vein of Rosenthal, and caudally to spinal veins
- some of the brainstem veins:
  - peduncular veins
  - lateral mesencephalic veins
  - median or lateral anterior pontomesencephalic vein(s)
  - transverse pontine veins
  - median or lateral anterior medullary vein(s)
  - transverse medullary veins

Dural venous sinuses

dural venous sinuses are channels located between the two layers of the dura mater that form the main drainage pathways of the brain, predominantly to the internal jugular veins (IJV)
they run alone, not parallel to the arteries
they are valveless, without a muscular layer in the wall ⇒ no flow regulation, possible bidirectional blood flow
they receive:
- blood from the cerebral veins
- cerebrospinal fluid (CSF) from the subarachnoid space (via arachnoid granulations)

Unpaired	Paired
superior sagittal sinus inferior sagittal sinus straight sinus occipital sinus intercavernous sinus	transverse sinus sigmoid sinus superior petrosal sinus inferior petrosal sinus cavernous sinus sphenoparietal sinus basilar venous plexus

superior sagittal sinus (SSS)
- the largest dural venous sinus, which runs along the superior aspect of the falx cerebri (from the foramen caecum anteriorly to its termination at the confluence of sinuses)
- receives venous blood from numerous superficial cortical veins and is connected with the superficial middle cerebral vein (via the vein of Trolard)
- there are frequent anatomic variations
  - hypoplasia of the middle part
  - variations in the anterior (rostral) segment
    - duplication of the rostral portion
    - duplication with unilateral hypoplasia
    - complete or bilateral hypoplasia of duplicated sinus
inferior sagittal sinus (ISS)
- runs along the inferior edge of the falx cerebri and drains blood into the straight sinus (merges with the great vein of Galen)
- It receives tributaries from the falx itself as well as some small veins from the medial surface of the hemispheres
straight sinus
- located at the junction between the falx cerebri and the tentorium cerebelli
- it receives blood from the inferior sagittal sinus and the vein of Galen, and some of the superior cerebellar veins
- runs posteroinferiorly towards the confluence of sinuses (approx. in 60% of cases)
  - sometimes, it terminates in the left or right transverse sinus
  - may be duplicated or hypoplastic (if hypoplastic or absent, a persistent falcine sinus is present, draining blood directly into the SSS)

occipital sinus
- lies on the inner surface of the occipital bone, receiving tributaries from the marginal sinus of the foramen magnum (which is connected to the vertebral venous plexus)
- sinus ends in the confluence of the sinuses
- may be quite extensive and off-midline (his position must be verified before surgery in the posterior fossa)
transverse sinus
- paired sinus arising from the confluence of the superior sagittal, occipital, and straight sinuses (confluence of sinuses)
- runs along the lateral border of the tentorium cerebelli and ends in the sigmoid sinus, just as it receives the superior petrosal sinus
- transverse sinuses are usually asymmetrical (hypo- or aplasia of the left sinus occurs in almost 60% of cases)
sigmoid sinus
- a continuation of the transverse sinus
- passes inferiorly in an “S”-shape and heads toward the jugular foramen, ending in the jugular bulb. From here, it continues as the internal jugular vein (IJV)

superior petrosal sinus
- a narrow dural venous sinus located within the anterolateral margin of the tentorium cerebelli. It spans from the cavernous to the transverse sinus
- its function is to drain the venous blood from the brainstem, temporal lobe, cerebellum, middle and inner ear into the transverse sinus
- It also connects with the inferior petrosal sinuses and the basilar plexus
inferior petrosal sinus
- a paired cranial venous channel that drains the cavernous sinus, midbrain, cerebellum, and inner ear
- emerges from the cavernous sinus within the middle cranial fossa and empties into the internal jugular vein
- may also drain into the suboccipital external vertebral venous plexus
cavernous sinus (CS)
- a paired sinus on either side of the pituitary fossa and body of the sphenoid bone, spanning from the orbit apex to the apex of the petrous temporal bone
- divided by numerous fibrous septi into a series of small caverns
- connected anteriorly and posteriorly by transverse junctions (intercavernous sinus), forming a closed venous ring
- the lateral wall of the CS is penetrated by the oculomotor, trochlear, and ophthalmic nerves. The center of the sinus is penetrated by the terminal segment of the ICA and the abducent nerve
- receives venous blood from:
  - inferior and superior ophthalmic veins (coming from the orbit through the superior orbital fissure. Via this route, the CS is connected with the veins of the face (pterygoid plexus – facial and angular vein – ophthalmic vein – CS), allowing for potential intracranial spread of inflammation
  - sphenoparietal sinus
  - superficial middle cerebral vein
- drainage is via:
  - superior petrosal sinus → the transverse sinus
  - inferior petrosal sinus → the jugular bulb
  - venous plexus on the internal carotid artery (ICA) → the basilar venous plexus
sphenoparietal sinus
- located along the posteroinferior ridge of the lesser wing of the sphenoid bone
- drains into the CS and receives tributaries from the superficial middle cerebral vein and middle meningeal vein

basilar venous plexus
- lies on the inner surface of the clivus and connects numerous regional venous structures:
  - superiorly – cavernous sinuses, superior petrosal sinuses, intercavernous sinuses
  - laterally – inferior petrosal sinuses
  - anteriorly – clival diploic veins
  - inferiorly through the foramen magnum – vertebral venous plexus, marginal sinus

Main cervical veins

there are three main jugular veins in the neck (external, internal, and anterior)
they are ultimately responsible for the venous drainage of the entire head and neck
in the supine position, blood from the head is primarily drained via the internal jugular vein (IJV)
in the upright position, the IJV collapses (due to a drop in hydrostatic pressure), and drainage is mediated by the vertebral vein
the cross-section area and shape of the IJV varies with head and body position

Internal jugular vein (IJV)

a paired vessel located within the carotid sheath on each side of the neck
drains venous blood from most of the skull, brain, and superficial structures of the head and neck
originates within the jugular foramen as a continuation of the sigmoid sinus; its origin is determined by a dilation known as the superior bulb
descends in the neurovascular bundle of the neck (lateral to the ICA and CCA, and the vagus nerve )
before its termination, it has another dilation (inferior bulb), sometimes with a valve above it ; the morphology of the valve varies:
- left side: tricuspid in 60% of cases
- right side: usually bicuspid or monocuspid, leading to a higher incidence of reflux
- the valve closes during diastole, and a short retrograde jet is visible on ultrasound
VJI terminates posterior to the sternal end of the clavicle, merging with the ipsilateral subclavian vein to form the brachiocephalic (innominate) vein

Occlusion of the right sigmoid sinus and IJV

Vertebral vein

a paired vessel located in the transverse foramina of the cervical vertebrae on either side of the neck
originates from the suboccipital plexus and traverses the transverse foramina of the C1-6, surrounding the vertebral artery (this plexus is considered the proximal part of the vertebral vein)
at the level of the C6 transverse foramen, the plexus merges into a single vessel
the vertebral vein then courses inferiorly and empties into the brachiocephalic vein via the orifice, which usually has a bicuspid valve