Arterial Supply And Venous Drainage Flashcards
From what arteries does the main blood supply to the cervical vertebrae arise?
Vertebral arteries
Ascending cervical arteries
Where do the vertebral arteries originate?
Subclavian arteries (as the V1 segment)
What is the relations of the V2 segment of the vertebral artery within the C6 transverse foramen?
Anterior to nerve roots
Covered by intertransversarii
Accompanied by SNS plexus from inferior cervical ganglion
Surrounded by venous plexus (vertebral vein)
What is the reference for the course of the vertebral artery itself?
Campero et al., 2011
What do the anterior branches of the vertebral arteries supply?
Ventral surface of cervical vertebral bodies (by directly penetrating cortical bone)
Uncovertebral joints
At what levels do the anterior branches of the vertebral arteries most commonly arise?
C3 and C4
What special anterior branch of the vertebral artery arises at C2? What does it supply?
Anterior ascending branch
Supplies:
- Ventral body of C2
- Dens
What is the alternate name for the posterior branches of the vertebral arteries?
Post-laminar arteries
What do the posterior branches of the vertebral arteries supply?
Dorsal surface of cervical laminae
Spinous processes
Where do the posterior branches of the vertebral arteries most commonly arises?
C4 and C5
What do the lateral branches of the vertebral arteries supply?
Mostly supply deep neck musculature
Osteoarticular branches supply facet joints
What is the course of the anterior part of the medial branches of the vertebral arteries?
Runs deep to PLL and anastomoses with its contralateral counterpart
What does the anterior part of the medial branch of the vertebral artery supply?
Main bloody supply to vertebral body:
- Enters dorsal surface
- Single nutrient vessel enters in midline and penetrates to half of vertebral body depth
What pattern does the posterior part of the medial branch of the vertebral artery form and what does it supply?
Arcuate pattern on posterior aspect of spinal canal Supplies: - Lamina - Spinous process - Pedicles - Facet joints
What is the alternate name for the medial branches of the vertebral arteries and why?
Lateral spinal branches
They enter the spinal canal from its lateral aspects via IV foramina
What is the main reference for the branches of the vertebral arteries?
Özgen et al., 2004
What are the common origins of the ascending cervical arteries? (Reference?)
Inferior thyroid artery (72.3%)
Thyrocervical trunk (10.7%)
(Daseler et al., 1959)
How do the ascending cervical arteries supply the vertebral column? What do they supply?
Give off Spinal branches that enter spinal canal via IV foramina Supply: - Spinal Cord and meninges (mainly) - Dorsal edges of vertebral bodies - Ventral laminae
What other branch of the vertebral artery supplies the spinal canal? Where does it arise?
Osseous branches of the anterior meningeal branch
Arises from medial surface of vertebral artery above C3 transverse foramen
Supplies:
- Body and dens of C2
- Articular plate of atlanto-occipital and atlantoaxial joints
What is the reference for the anterior meningeal branch?
Campero et al., 2011
From what arteries does the arterial supply to the thoracic vertebral column arise?
Posterior intercostal arteries
As the posterior intercostal arteries cross the anterolateral aspects of the thoracic vertebral bodies, what branches supply these aspects?
Periosteal branches -> Lie on and supply surface
Equatorial branches -> Penetrate cortical bone and supply ventral vertebral bodies
At what level do the spinal branches of the posterior intercostal arteries enter the spinal canal?
At the level of the costotransverse joints
What do the spinal branches of the posterior intercostal arteries supply?
Anterior branch -> Dorsal aspect of vertebral body
Posterior branch -> Ventral aspect of lamina
From where does the blood supply to the lumbar vertebral column arise?
Lumbar arteries
What do the posterior spinal canal branches of the lumbar arteries supply? (Reference?)
Epidural fat Dural sac Base of spinal processes Lamina: - The branch to these also supplies both the superior and inferior articular facets (Bogduk, 2005)
Where do the lumbar arteries arise?
4 pairs from posterolateral abdominal aorta
5th pair from middle sacral artery
Where do the primary periosteal arteries arise?
From superior and inferior surfaces of lumbar arteries
How many primary periosteal arteries arise from each lumbar artery?
10-20 per lumbar artery
What anastomosis do the most posterior pairs of primary periosteal arteries form?
Precostal anastomosis
Where do the metaphyseal arteries lie?
In the upper and lower metaphyses of each vertebral bodies
In what plane do the metaphyseal arteries run and what arteries may join them?
Run horizontally
Primary periosteal arteries join them
In what individuals are the secondary periosteal arteries more marked?
Elderly
What do the spinal branches of the lumbar arteries hook over?
The lateral aspect of PLL
What branches do the spinal arteries from the lumbar arteries give off? What is the course of these branches?
Ascending and descending branches:
- May anastomose with those on adjacent vertebrae
- May anastomose with contralateral side = Post-central anastomosis
What two diagrams are important for understanding the arterial supply to the lumbar vertebrae?
Ratcliffe, 1980
Bogduk, 2005
What arteries give branches to supply the sacrum?
Iliolumbar arteries
Lateral sacral arteries
Median sacral artery
Where do the iliolumbar arteries arise from?
Usually from posterior trunk of the internal iliac artery
May arise directly from posterior aspect of internal iliac artery
Where do the iliolumbar arteries run in relation to the SIJs?
Superolaterally in front of the SIJs
A lumbar branch of the iliolumbar arteries can anastomose with which artery?
4th lumbar artery
Describe the spinal branch of the iliolumbar artery?
Small
Enters spinal canal via IV foramen between L5 and S1
What is the reference for the iliolumbar arteries?
Teli et al., 2013
Where do the lateral sacral arteries arise?
A superior and inferior branch on each side from the posterior aspect of the internal iliac arteries
What is the course of the lateral sacral arteries?
Pass medially
Descend anterior to sacral ventral rami
Describe the spinal branches of the lateral sacral arteries
Pass through anterior sacral foramina
Supply vertebrae similarly to other spinal branches
Where does the median sacral artery arise?
An unpaired branch from the posterior aspect of the abdominal aorta prior to bifurcation
What is the course of the median sacral artery?
Runs anterior to:
- L4 and L5
- Sacrum
- Coccyx
Where does the median sacral artery give off branches and what do they do?
Anterior to sacrum:
- Anastomose with lateral sacral arteries and support the spinal branches
How does the median sacral artery supply the anterior sacrum?
Small periosteal and equatorial branches
Why are IV discs avascular?
The blood vessels surrounding them during early development gradually regress
What parts of the vertebral bodies are vascular and avascular?
Vascular = More central parts Avascular = Part of VB immediately adjacent to IV disc
The central vascular region of a vertebral body can be divided into 3 parts. What are these?
Part supplied by nutrient artery Part supplied by metaphyseal artery Part supplied by peripheral arteries: - Equatorial - (Secondary) periosteal
Why does the zoning of blood supply to the vertebral bodies arise?
Probably due to arrangement of IV disc annulus fibres dictating where diffusion of oxygen and nutrients is required
Where do mature IV discs rely on diffusion of nutrients from?
Vertebral endplate
How are the IV discs supplied with nutrients?
- Vertebral endplates act as semipermeable membranes for exchange of nutrients into lamellae of annulus fibres
- Fluid trapped between lamellae and moves in the vertical plane
- Frequent fluid movement -> Speeds up diffusion
As we age, the lumens of arteries narrow. What arteries are affected first and what are examples of these in the vertebral column? (Reference?)
Tortuous arteries affected first:
- Nutrient arteries
- Metaphyseal arteries
(Palastanga and Soames, 2012)
Why does the nucleus pulposus dehydrate and lose its elastic properties with age? (References?)
Loses proteoglycans and gains collagen (Moore and Dalley, 2006)
- Results in loss of glycosaminoglycans
- Reduced osmotic pressure of disc matrix
- Loss of hydration (Urban and Roberts, 2003)
What happens when the nucleus pulposus dehydrates and becomes inelastic?
IV disc stiffening:
- Loses ability to deform and reform under pressure
- When load is applied it loses height
When and where can the first signs of IV disc degeneration be seen?
In lumbar discs of 11-16 year olds
What percentage of teenagers have mild IV disc degeneration?
20%
In what individuals is there a steeper increase in prevalence of IV disc degeneration with age?
Males
What percentage of 50 year olds and 70 year olds have severe IV disc degeneration?
50 year olds - 10%
70 year olds - 60%
Why do IV discs have insufficient healing ability? (Reference?)
Poor blood supply
Endplate permeability depletes with age
(Palastanga and Soames, 2012)
When the IV discs degenerate, what structures is excess pressure put on?
Zygapophyseal joints
Ligamentum flavum
Why might IV disc degeneration result in the disc bulging into the spinal canal?
IV disc may thicken
IV disc may remodel
IV disc loses elasticity so cannot deform properly
What happens if an IV disc bulges into the spinal canal?
Spinal stenosis Presents with: - Sciatica - Foot drop - Mobility issues - Bladder/Bowel incontinence
What are Schmorl’s nodes? (Reference?)
Vertical protrusion/Herniation of nucleus pulposus through cartilaginous and bony endplates:
- Into adjacent vertebral bodies
- Both upper and lower vertebrae to disc affected
(Matter and Rehman, 2014)
What are the aetiologies of Schmorl’s nodes?
Trauma Idiopathic Developmental Genetic Reduced bone mineral density
Why is the immune system the cause of symptoms in Schmorl’s nodes? (Reference?)
Nucleus pulposus Herniation is “non-self” tissue:
- When it contacts blood -> Autoimmunity
(Wang et al., 2016)
What are the symptoms of Schmorl’s nodes? (References?)
Severe back pain
Inflammation
(Abu-Ghanem et al., 2013)
Where are the cervical and lumbar enlargements?
Cervical = C4-T1 Lumbar = T11-S1
Why might the cervical and lumbar enlargements require greater arterial supply?
Due to increased neural output to the upper and lower limbs respectively
What are the large calibrate anterior segmental radiculomedullary arteries to the spinal cord enlargements? (Reference?)
Artery of cervical enlargement (or Lazorthes)
Artery of Adamkiewicz (lumbar enlargement)
(Becske et al., 2015)
What does Bulut et al., (2016) suggest might be a reason for greater cervical blood supply?
Cervical lordosis
How might axial loading result in greater arterial supply to the lumbar spine? (References?)
Vertebral axial loading increased as lower lumbar levels approached (Moskovich, 2001)
In mice, chronic axial loading (Papuga et al., 2010)
- Increases marrow vascularity
- Increases cellularity
What percentage of stokes involve the spinal cord?
1%
Why are posterior spinal artery infractions uncommon? (Reference?)
Extensive lateral vascular network
Rabinstein and Resnick, 2009
How does a spinal cord infarction present? (Reference?)
Numbness/Tingling/Aching Lower limb weakness/cramping Bowel/Bladder incontinence Pain Loss of sensory function: - If posterior spinal artery occluded (Satran, 1988)
What is the diagnostic imaging of choice in spinal cord infarction?
MRI
What is the pathogenesis of spinal cord infarction?
Unknown
What is Beck’s syndrome?
Anterior spinal artery syndrome i.e. A form of spinal cord infarction
What does the anterior spinal artery supply and via what? (Reference?)
Anterior 2/3 of spinal cord via sulcal (central) artery
Kim et al., 2014
What is the pathogenesis of Beck’s syndrome?
Hypoperfusion of anterior spinal artery:
- Due to occlusion
- Results in ischaemia of anterior 2/3 of spinal cord
What are some of the causes of Beck’s syndrome? (Reference?)
Atherosclerosis Aortic aneurysm Aortic trauma Acute IV disc Herniation Cervical spondylosis Kyphoscoliosis Trauma to spinal column Emboli (Schneider, 2010)
What are the symptoms of Beck’s syndrome? (Reference?)
Acute and painful myelopathy with incontinence
Bilateral loss of pain and temperature sensation below lesion
Bilateral motor paralysis below legion
ANS dysfunction -> Orthostatic hypotension
What senses are left intact in Beck’s syndrome and why?
Vibration and proprioception
DCMLS left intact (supplied by posterior spinal artery)
How is Beck’s syndrome diagnosed? (Reference?)
Clinical examination to determine vertebral level
Diffusion-weighted MRI
(Reynolds et al., 2014)
What are the treatments of Beck’s syndrome?
Treat cause
Supportive therapy
What percentage of surviving patients have little or no neurological improvement from Beck’s syndrome? (Reference?)
50%
Schneider, 2010
What percentage of Beck’s syndrome patients recover? (Reference?)
10-15%
Healthh, 2016
In what patients is the prognosis of Beck’s syndrome better?
If they have progressive recovery
If recovery evident in first 24 hours
What is the mortality rate of Beck’s syndrome? (Reference?)
20% - It is the spinal cord syndrome with worst prognosis
Healthh, 2016
What is the most common cord syndrome? (Reference?)
Central cord syndrome
Weider et al., 2015
What does the intrinsic venous system drain?
Spinal cord ONLY
Does not drain vertebral column
What do the sulcal (central) veins drain blood rom?
Medial aspects of anterior grey horns
Anterior grey commissure
White matter of anterior funniculus
Where do the sulcal (central) veins drain to? (Reference?)
ANTERIOR median vein
Santillan et al., 2012
What do the radial veins drain?
Peripheral grey matter and adjacent white matter of spinal cord
Where do the radial veins drain?
Into a venous ring on the spinal surface:
- Pia venous network (via longitudinal intersegmental bridges)
- Longitudinal extrinsic venous system
Eventually drain to anterior OR posterior median veins
In what directions does the pial venous network run in?
Dorsal
Centrally
Laterally
Describe the anterolaterally situated longitudinal veins of the pial venous network (reference?)
Most continuous parts of pial venous network
Can replace anterior median vein if disrupted
(Thron, 2016)
What connects the longitudinal veins of the pial venous network?
Superficial transverse veins
What regions are most rich in ventral pial veins?
Cervical
Upper thoracic
Lumbosacral
What regions are most rich in dorsal pial veins?
Upper cervical
Extremes of thoracic regions
What is the reference for distribution of the ventral and dorsal pial veins?
Griessenauer et al., 2015
How many anterior median veins of the longitudinal extrinsic venous system are there in each region of the spinal cord?
Upper cervical = 1 Lower cervical = 3 Upper thoracic = 3 Lower thoracic = 2 Lumbosacral = Converge into 1 again
Where does the anterior median vein continue along after the end of the spinal cord? What does it continue as? (Reference?)
Continues along film terminale
Continues as terminal vein to end of dural sac
(Santillan et al., 2012)
How many posterior median veins of the longitudinal extrinsic venous system are there in each region of the spinal cord?
Upper cervical = 1 Lower cervical = 3 Cervicothoracic junction = 2 Thoracic = 2 Thoracolumbar junction = 1
What do the radiculomedullary veins accompany?
Nerve roots
How many anterior radiculomedullary veins are there? (Reference?)
8-14
Gillilan, 1970
How many posterior radiculomedullary veins are there? (Reference?)
5-10
Thron, 1988
Describe the largest radiculomedullary vein
Great anterior radiculomedullary vein:
- Drains anterior thoracic cord
- Accompanies T11-L3 nerve roots
What is the route of drainage of the longitudinal extrinsic venous system?
Median veins (anterior and posterior) -> Radiculomedullary veins Radiculomedullary veins -> Extradural venous plexus
What did older studies believed prevented reflux from the radiculomedullary veins into the longitudinal extrinsic venous system? Name some of these studies
Bicuspid valves in radiculomedullary veins:
- Clemens, 1961
- Oswald, 1961
- Tadie et al., 1979
- Vogelsang, 1970
What study disproved the original theory of preventing radiculomedullary vein reflux?
A cadaver study by Groen et al., (1997)
What did Van der Kuip et al., (1999) find to prevent reflex in the radiculomedullary veins?
Dural folds into vein lumen:
- Do not touch opposite side so not valves
Tortuous course
Bottleneck of vein:
- Narrowed subdural part
- Widened extradural and intradural parts
What is the other name for the extradural vertebral venous plexus?
Batson’s plexus
What are the three divisions of the extradural vertebral venous plexus?
Internal vertebral plexus
External vertebral plexus
Basivertebral plexus
What does the extradural vertebral venous plexus drain blood from?
Radiculomedullary veins (spinal cord) Vertebral column itself
What do the anterior and posterior parts of the internal vertebral plexus communicate with superiorly? (Reference?)
Suboccipital venous system
Tubbs et al., 2007
How many longitudinal veins are there in the internal vertebral plexus?
2 anterior
2 posterior
Where do the anterior intervertebral veins of the IVP lie?
On either side of the PLL
How do the anterior veins of the IVP join the basivertebral plexus?
Via transverse branches
In what direction do the anterior veins of the IVP increase in calibre?
Craniocaudal
Where do the posterior veins of the IVP lie?
Anterior to ligamentum flavum
How do the posterior veins of the IVP connect to the posterior external vertebral plexus?
Via perforating branches
What forms the anterior external vertebral plexus? (Reference?)
Tributaries from anterior vertebral body
Agar et al., 2016
What forms the posterior external vertebral plexus? (Reference?)
Veins passing through ligamentum flavum
Agur et al., 2016
What does the posterior external vertebral plexus drain?
Vertebral arches
Transverse and spinous processes
How do the internal and external vertebral plexuses communicate?
Intervertebral veins within the IV foramina
Where do the basivertebral plexuses form and run?
Form within vertebral bodies
Run horizontally within vertebral bodies
Where does the basivertebral plexus emerge?
Foramina on surface of vertebral bodies:
- Particularly on posterior surface
Where do the basivertebral plexuses drain?
Some to anterior external vertebral plexus
Most to anterior internal vertebral plexus
Where do the intervertebral veins drain in the cervical region? (Reference?)
Vertebral veins
Deep cervical veins
Jugular veins
(Lasjaunias et al., 1990)
Where do the intervertebral veins drain in the thoracic region?
Azygos system (right) Hemiazygos: - On left - Joins azygos around T9 level Accessory hemiazygos vein drains T3-T8 on left
Where do the intervertebral veins drain in the lumbosacral region?
Ascending lumbar veins:
- Drain to azygos and hemiazygos veins
- Also drain to IVC via 4 horizontal lumbar veins
What did Gillot et al., (1968) show in regards to lumbar spinal venous drainage?
Lumbar Spinal venous blood can drain to:
- Left renal vein
- Vein of crus of diaphragm
Where do sacral intervertebral veins drain to?
Lateral sacral veins
Internal iliac veins
What is the seed and soil theory of metastatic spread? (Reference?)
Some organs have a predisposition to metastases
Paget, 1889
What did Batson, (1940) show in regards to metastatic spread?
Anatomical studies:
- Preferential drainage to vertebral column
- eg. Emboli from prostate -> Vertebral venous system -> Bones of spine, pelvis and skull
What is the modern understanding of metastatic spread? (Reference?)
Both theories applicable
Both used together can help understanding of body systems
(Algra et al., 2013)
What is contiguous spread?
Local invasion
What is compartmental spread?
Direct seeding to body cavities
Eg. Abdominal organ -> Peritoneum
What is haematogenous spread?
Spread via vasculature:
- Arteries
- Veins
- Capillaries
What is lymphangitic spread?
Spread via lymph vessels
Preferentially to regional lymph nodes and later to distant sites
What is the reference for the four routes of disease spread?
Rejniak, 2016
What are the general steps of the invasion-metastasis cascade?
- Invasion (through ECM and stromal layers)
- Angiogenesis
- Intravasation into vessel lumens
- Circulation
- Arresting at distant organ sites
- Extravasation into parenchyma
- Survival in foreign micro environments
- Colonisation and growth via proliferation programs
What is the reference for the invasion-metastasis cascade?
Valastyan and Weinberg, 2011
What does the invasion-metastasis cascade apply to?
Epithelial cells in primary tumours
What are the primary cancers that tend to metastasise to bone?
Breast
Lung
PROSTATE
What are the signs and symptoms of bone cancer?
Persistent bone pain: - Worsens over time - Present at night Swelling and redness over bone -> Difficult movement if at joint Noticeable lump Weakness -> Easily fractured
How is bone cancer diagnosed?
Bloods Imaging: - CXR - Bone X-ray - CT or CT/PET - MRI Biopsy: - Bone biopsy - Core needle biopsy - Surgical biopsy
What are the treatment options for bone cancer?
Surgical resection and reconstruction/replacement
Chemotherapy
Radiotherapy
How many people with primary bone cancer will live for at least 5 years from diagnosis?
6 out of 10
What does the prognosis of a secondary bone cancer depend on?
Primary tumour:
- Presentation
- Location
