King Ch 3 - Venous drainage Flashcards
Venous drainage of the brain and spinal cord (23 cards)
What type of valves are found in the venous sinuses?
Poorly developed and scarce valves
Name the 3 main transverse connections from left to right side in the venous sinuses.
Midline cavernous sinus, transverse sinus, anastomoses of the spinal system
Where are all venous sinuses located in relation to the dura mater?
Outside the dura mater; between dura mater and periosteum in the head, and in the epidural space in the vertebral canal.
What is the dorsal system of sinuses responsible for draining?
Dorsal areas of the forebrain, including most of the cortex of the cerebral hemispheres.
Drained by the dorsal cerebral veins and deeper areas by the great cerebral vein
What is drained by the ventral system of sinuses?
Ventral areas of the forebrain, face, nasal cavity, orbit, and upper teeth
Drained by the ventral cerebral veins
What is the function of the angularis oculi vein?
Drains the skin in the region of the upper eyelid
What is another name for the connecting sinus?
Sigmoid sinus
What does the connecting sinus connect?
Dorsal system via the transverse sinus and ventral system via the petrosal sinuses
What are the components of the dorsal system of sinuses?
- Dorsal sagittal sinus
- Straight sinus
- Transverse sinus
What are the components of the ventral system of sinuses?
- Cavernous sinus
- Dorsal petrosal sinus
- Ventral petrosal sinus
What is the primary drainage path of the cranial venous sinuses?
Into the maxillary vein via the connecting sinus
What is notable about the veins of the brain?
They have no valves and are very thin-walled
What are the two groups of cerebral veins?
Superficial and deep cerebral veins
How do the superficial cerebral veins drain?
- drain by dorsal cerebral veins
(four or five large ones) into the dorsal system of cranial venous sinuses - AND drain by ventral cerebral veins into the ventral system via the dorsal petrosal sinus
What do the deep cerebral veins drain?
Deep dorsal parts of the hemispheres, which empty into the great cerebral cein and then into the straight sinus
Describe the drainage of veins of the spinal cord
- The veins of the spinal cord empty into the ventral spinal vein (or veins), which
accompanies the ventral spinal artery along the ventral fissure of the spinal cord. - Other veins drain from the spinal cord into the network of veins lying on the surface of the cord.
- Veins accompanying the roots of the spinal nerves drain the ventral vein and the venous network into the longitudinal spinal sinuses.
- The spinal sinuses also drain the vertebral bodies, including their haemopoietic tissues.
What is the arrangement of the spinal system of venous sinuses?
A pair of longitudinal spinal sinuses running parallel along the whole length of the vertebral canal floor
Valves are absent or poorly developed.
Transverse connects from one side to the other occurs erratically at vertebral junctions.
What do the spinal sinuses drain?
The whole length of the spinal cord and the cauda equina
Describe the connections of spinal sinuses to the cranial system of sinuses
At the foramen magnum there is direct continuity, end to end, of the longitudinal spinal sinuses with the connecting system of cranial sinuses
How do the longitudinal spinal sinuses drain into the systemic circulation?
By intervertebral veins
These are segmental and pass through intervertebral foraminae alongside nerves
What can happen if venous drainage is obstructed?
Capillary hemorrhage and severe damage to the brain
What is paradoxical embolism?
Increased abdominal or thoracic pressure causes blood flow against the valves that guard intervertebral veins (which connect venous sinuses with caudal vena cava), and hence microorganisms and tumours cells from viscera or other body areas can reach the head.
What advanced imaging technique is replacing angiography?
Functional magnetic resonance imaging
