arterial supply, venous and lymphatic drainage of the VC Flashcards
Bone receives up to what?
10% of cardiac output, allowing it to have a high level of remodelling and repair
Hence disruption of blood supply can impede what?
repair and growth
Vertebral column is one of what?
the largest stores of bone marrow in the body
2 types of bone marrow?
Red marrow and Yellow marrow
The vertebral column receives its blood supply segmentally from where?
segmental arteries, Vessels lying adjacent to the vertebral column give branches
red marrow is what?
Red marrow → primary site of haematopoiesis, hence needs rich vasculature
The cervical vertebrae are supplied by what?
the vertebral and ascending cervical arteries
Vertebral artery, along with vertebral veins and sympathetic nerves, travel where? what is the exception?
through the transverse foramen of C1-6, Exception of C7 where the artery passes around the vertebra and not through the transverse foramen
can variations occur in the arterial supply?
yes, Study found 20% of specimens had anatomical variation of vertebral artery (Accessory vessels, lateral loops)
Also in 20% the vertebral artery entered through the transverse foramen of a vertebra other than C6
Vertebral artery gives spinal branches which enter where?
the vertebral canal through the intervertebral foramen
Ascending cervical artery runs along where?
the anterior tubercles of the transverse processes at the level of C4
Ascending cervical artery
Also gives spinous branches which enter where?
the vertebral canal through the intervertebral foramen
Ascending cervical artery Has been shown to only give spinal branches to where?
to the C4-5 and C3-4 foramen (occasionally C2-3)
There is evidence that C5-6 and C6-7 are supplied by what?
branches from the deep cervical artery and the cost cervical trunk
The thoracic vertebrae are supplied by what?
the posterior intercostal and subcostal arteries
First 2 pairs of post. Intercostal arteries are branches of what?
the superior intercostal artery from costo-cervical trunk of the subclavian
Pairs 3-11 arise from what?
the posterior wall of the thoracic aorta
variances of arterial supply of thoracic region?
In most individuals these pared vessels arise symmetrically.
However, in a cadaveric study found that these vessels were asymmetrically distributed in 16% of specimens
One vessel may also supply 2 vertebrae
The 12th pair of arterial supply thoracic region are termed what?
the subcostal arteries as they arise below the ribs
Spinal branches enter where?
through the intervertebral foramen
L1-4 are supplied by what?
the lumbar arteries
how many paired lumbar arteries are there?
4
where do the lumbar arteries arise?
arise from posterior wall of abdominal aorta
Pass laterally along the vertebra until they reach the intervertebral foramen
Lumbar arteries usually arise ?
symmetrically
L5 is supplied by what?
lumbar branches from the middle sacral and iliolumbar arteries
Branches from the middle sacral artery are much..?
smaller than the lumbar segments
Branches from the middle sacral artery are Reinforced by?
posteriorly by iliolumbar branches and a communicating artery from L4
The sacrum and coccyx are supplied by what?
the lateral sacral arteries which also show a wide range of variation
arterial blood supply of cervical vertebrae?
Vertebral and ascending cervical
cervical arterial supply arising from?
Subclavian and inferior thyroid
arterial blood supply of thoracic vertebrae?
Posterior intercostal and subcostal
thoracic arterial supply arising from?
Subclavian and thoracic aorta
arterial blood supply of lumbar 1-4 vertebrae?
lumbar
lumbar 1-4 arterial supply arising from?
abdominal aorta
arterial blood supply of lumbar 5 vertebrae?
Middle sacral and iliolumbar
lumbar 5 arterial supply arising from?
Abdominal aorta and internal iliac
sacrum and coccyx arterial supply arising from?
lateral sacral
sacrum and coccyx arterial supply arising from?
internal iliac (post. division)
The main segmental arteries supplying each region give what?
10-20 periosteal branches
main segmental arteries supply what?
Supply the periosteum of vertebrae
Periosteal branches of adjacent segmental arteries anastomose where? and are More prominent between?
on anterolateral and posterior surfaces,More prominent between L4-5
Metaphyseal anastomosis
Surrounds where?
the anterior and lateral surfaces
Beyond the spinal branch, segmental artery branches into what?
an anterior and posterior artery
Anterior part → ?
to other surrounding tissues
Posterior part →?
supplies the posterior parts of the vertebra
Spinal branch branches into what?
Anterior vertebral canal artery
Segmental medullary artery
Posterior vertebral canal artery
Anterior vertebral canal artery → ?
to vertebral body
Segmental medullary artery → ?
to spinal cord (covered later)
Posterior vertebral canal artery → ?
to vertebral arch
The anterior canal branches send nutrient arteries via what?
the nutrient foramen into the body to supply the red marrow
Segmental arteries → ?
Periosteal and Equatorial branches
Segmental arteries →? → ? → ?
Spinal branch, Anterior and posterior canal branches, (from ant. Canal) Nutrient arteries
There are 3 types of intra-osseous arteries?
peripheral, equatorial, metaphyseal
Peripheral →?
supply the outer circumference
Equatorial → ?
supply the central core of the body (along with the nutrient arteries)
Metaphyseal →?
supply an annular zone between
This distribution results in what?
zoning of the blood supply to the vertebral body
Mature intervertebral discs are what? apart from what?
largely avascular structures, Apart from periphery which receives supply from adjacent vessels
what to IV discs rely on in terms of blood supply?
Rely on diffusion from the trabecular bone of adjacent vertebrae for nutrients
Hence any disruption of flow to the vertebral bodies will cause what?
will heavily impact the IVDs
Branches of metaphyseal and nutrient arteries form what?
a capillary plexus in the endplate
Cells within the IV disc require what?
require nutrition in order to maintain their integrity, hence a good blood supply is essentia
Because blood supply is from vertebral bodies, supply of the IVD is what?
zoned
As aging occurs, arteries begin to do what?
gradually narrow and deteriorate
what are the first arteries to be affected in disc degeneration?
Metaphyseal and nutrient arteries first affected
what happens to the peripheral arteries in disc degeneration?
peripheral arteries increase in number, IV disc also gains greater peripheral supply
what is linked to disc degeneration ?
Decreased blood supply
It has been shown that disc degeneration first appears where?
at the centre of the disc
can periphery can be capable of repair long after centre has degenerated
yes
what else can also be contributed to by smoking and other pathologies ?
Reduction in blood supply can also be contributed to by smoking and other pathologies
Pathologies such as scoliosis can cause the cartilaginous end plate to calcify, limiting blood flow and causing degeneration of the disc
what is Schmorl’s nodes?
herniation of nucleus pulposus through bony and cartilaginous end plate into the adjacent vertebral body
where does Schmorl’s nodes occur?
Occur frequently in humans and are usually asymptomatic but can be associated with back pain
where is Schmorl’s nodes usually observed?
Commonly observed on radiographs and at autopsy (studies have found that ~73% of the population present with small herniations)
does Schmorl’s nodes occur more frequently in men or women?
men 76% of cases
where does Schmorl’s nodes occur?
Tends to occur at the thoracolumbar transition region (T7-L1)
what has Schmorl’s nodes been correlated with?
disc degeneration in some studies
The spinal cord is supplied by how mant longitudinal arteries arising from where
3 longitudinal arteries arising from the vertebral artery
anterior spinal artery runs where?
in the anterior median sulcus
anterior spinal artery branches into what?
sulcal arteries
what are the 3 longitudinal arteries supply the spinal cord?
anterior spinal artery
2x posterior spinal arteries
where do the posterior spinal arteries run?
down the posterolateral sulcus
what do the posterior spinal arteries divide into?
2 collateral arteries that branch to form the pia plexus?
where do the 2 posterior spinal arteries supply?
1/3 of spinal cord
largest anterior segmental medullary artery (artery of Adamkiewicz) arises where?and supplies where?
around T12 or L1 → supplies inf. 2/3 of spinal cord
where is there less supply in the spinal cord?
Less supply in mid thoracic region compared to cervical and thoracolumbar regions
where do the radicular arteries supply?
they supply spinal nerve roots, but segmental medullary arteries are also referred to as radicular feeder arteries.
radicular arteries end where before reaching where?
end in the nerve root before reaching the ant. Or post. Spinal arteries, but segmental medullary go on to feed into the spinal arteries.
where do the anterior and posterior segmental medullary arteries enter?
through nerve roots
what is spinal cord infarction?
death of nervous tissue as a result of interrupted blood supply
how common or rare is spinal cord infarction?
Relatively rare, accounts for 0.3-1% of strokes
If the blood supply is damaged or interrupted (e.g. during surgery) depending if it’s anterior or posterior what can occur?
different areas of the spinal cord will be damaged, resulting in specific, different neurological consequences
damage to anterior in relation to spinal cord infarction results in?
loss of motor functions
damage to posterior in relation to spinal cord infarction results in?
loss of sensory functions
which spinal cord infarction is more common?
95% of spinal cord infractions occur anteriorly
where is spinal cord infarction most common and why?
thoracic region due to reduced blood supply
what would a patient present with, with spinal cord infarction?
present with sudden onset of symptoms with rapid progression.
However, due to it’s rarity the exact course isn’t well documented and symptoms and progression can vary
what are the causes of spinal cord infarction?
Vertebral fractures
Dislocations
Vasculitis
external compression (e.g. abdominal tumours)
current treatments of spinal cord infarction?
Currently treatment is aimed at any detectable causes
what is the venous drainage of spinal cord?
6 longitudinal veins that run down the length of the spinal cord including :
3 anterior and 3 posterior spinal veins
anteromedian vein is located where?
located deep - In the lumbar region
anteromedian vein is accompanied by what?
2 anterolateral veins
what is the dominant vessel in the lumbar area?
A midline posteromedian vein
spinal cord receives blood from where?
neural tissue via sulcal veins
sulcal veins drain where?
into the radicular veins then drain to the internal vertebrae venous plexus
blood from the external vertebrae plexus drains where?
drains into the systemic veins including:
Mainly innominate veins at cervical level
Azygos vein at thoracic level
Ascending lumbar vein at the lumbar level
the venous plexus in relation to thhe VC is formed by what?
spinal veins, both inside and outside the vertebral canal
the plexuses includes what?
internal (or epidural) and external vertebral venous plexus
what does the venous plexuses lack?
valves
the internal vertebral venous plexus is located where?
Located beneath the bony elements of the vertebral foramina
the internal vertebral venous plexus is embedded where?
Embedded in loose areolar tissue layer known as epidural adipose tissue
the internal vertebral venous plexus is divided into what?
Divided into the anterior and posterior vertebral plexus
what is involved in the internal vertebral venous plexus?
4 longitudinal channels, two along posterior aspect of vertebral canal, two along the anterior aspect of canal
does the internal vertebral venous plexus have valves?
no
The anterior and posterior plexuses (IVVP) communicate freely with what?
one another through a series ofvenous rings, there isone opposite each vertebra.
At the foramen magnum the anterior and posterior pleaxuses (IVVP) form what?
an intricate net-work which opens into the vertebral vein
Radicular veins and the basivertebral veins all join what?
the internal vertebral venous plexuses and drain the vertebral column
The vertebral vein is formed from what?
The vertebral vein is formed from small tributaries springing from this plexus
where is the anterior and posterior pleaxuses (IVVP) found?
anterior- Found on the posterior surfaces of the vertebral bodies
posterior- Found in front of the vertebral arches
The two anterior channels lie where?
either side of the posterior ligament
The posterior channels lie where?
Lie on the inner surfaces of the laminae and ligament flava
where does the anterior internal venous plexus anastomose?
Anastomosing across the midline
where does the posterior internal venous plexus anastomose?
Anastomose across the midline with some vessels emerging to join the posterior external plexus by passing between the free medial edges of the ligament flava
the anterior internal venous plexus recieves what?
Receiving the basivertebral vein, anterior to the ligament
what is the External Vertebral Venous Plexus?
Network of veins surrounding the external aspect of the vertebral column
what is the External Vertebral Venous Plexus divided up into?
Divided into an anterior plexus surrounding the vertebral bodies and a posterior plexus associated with the neural arches
what does the External Vertebral Venous Plexus communicate with?
Communicates with the internal venous plexuses through the intervertebral foramina
what drains into the external vertebral plexus?
The internal plexus drains into the external plexus, which in turn drains into thevertebral veins of the neckandsegmental(intercostal, lumbar, and sacral)veins of the trunk
the anterior external venous plexus surrounds what?
vertebral body
anterior external venous plexus communicated with what?
Communicates with the basivertebral veins and intervertbral veins
where is the posterior external venous plexus found?
Found along the posterior surfaces of the vertebral arches and the spinous process of the vertebrae.
the posterior external venous plexus best developed where?
cervical region
The intervertebral veins go where?
through the intervertebral foramina with the spinal nerves
The intervertebral veins drain what?
The intervertebral veins drain the internal and external vertebral plexus
Basivertebral veins come from where?
come from the foramina on the posterior surfaces of the vertebral bodies
Basivertebral veins run through where?
the vertebral body, communicate posteriorly with the internal vertebral plexus and anteriorly with the external vertebral venous plexus
do the intervertebral veins and basivertebral veins have valves?
unknown
what could this unknown fact about the veins explain?
This could be an explanation as to why pelvic neoplasms can metastasize in vertebral bodies
e.g. prostate carcinoma
what follows the arteries?
Deep lymphatic vessels commonly
At each level, lymph drains to their associated nodes?
Cervical vertebral column → Deep cervical nodes
Thoracic → Posterior intercostal nodes
Lumbar column → Lateral aortic and retro-aortic nodes
Pelvis → Lateral sacral and internal iliac nodes
The lymphatic system can frequently act what?
act as a pathway for the spread of disease, such as cancer metastasis and various inflammatory disorders
Breast cancer is frequently associated with what?
bone cancer due to the fact breast tissues drain to the axillary lymph nodes – proving a pathway for the spread of disease
how many breast cancer patients develop bone cancer?
Up to 70% of terminal breast cancer patients also develop bone cancer (primarily in the vertebral column) due to the extensive lymphatic network around the vertebral column
The spread of cancer from one part of the body to another is named ?
METASTASIS
A metastatic tumour is a what?
tumour that is formed by cells that have spread
Cells can break off the tumour and what happens?
therefore travel to other parts of the body through the bloodstream or lymphatic system. This can result in them settling in a different area and ending up in any organ or tissue
The most common site of metastasis is where?
the vertebral column
Spinal column metastases is commonly what?
secondary to malignant neoplasm of the breast, lung and prostate
In 90% of patients, what is the initial symptom?
pain
what can occur in metastatic spread
Fracturing or collapsing of the vertebral body, pressure on theperiosteumfrom within thevertebra, ornerve rootandspinal cord compression
how many terminally ill patients will have metastases and where?
30-90% of terminally ill patients with cancer have metastases somewhere spinal column segment
The principal process of spinal metastasis is through
what?
the Batson venous plexus
who first described metastasis and when?
Anatomist Oscar Vivian Batson, who first described it in 1940
Network of valve-lessveins connecting what?
the deep pelvicveins and thoracic veins to theinternal vertebral venous plexuses
metastasis believed to what?
Believed to provide a route for spread of pelvic cancer metastases/ infections to the spine due to reversed blood flow
Provide a route for what?
Provide a route for breast cancer metastases to vertebrae, skull, pelvic bones
In 1940, Batson injected contrast into the vein of the penis in males and veins of the breast in women
Results showed what?
that tumor cells spreading in blood into the spinal veins.
