1. Gross Anatomy: Spinal Cord and Meninges
Know what levels of the spinal cord are associated with the vertebral column. Esp T12, L1, L2

2. Spinal Cord The spinal cord: occupies the vertebral canal
in infants the spinal cord extends into the sacrum
in the adult the cord extends from the cranial border of the atlas to L2
level of termination is slightly more superior in flexion

3. Spinal Cord The spinal cord is: part of the central nervous system.
segmental in nature
What is a spinal cord segment?
How many segments are there?
Note the relationship of the “nerves” to the spinal cord:
Only one coccygeal nerve
Note the C1 nerve comes straight off
But towards lower end of thoracic and sacral/lumbar region they have to tail off

4. Dermatomes, Myotomes and Sclerotomes

5. Spinal Cord Enlargements
Cervical Enlargement
the larger and more pronounced of the enlargements
extends from about C3 to T2
Lumbar Enlargement
extends from L1 to S3
Below the lumbar enlargement, the cord tapers to the conus medullaris.
Enlargements are due to mostly extremities. The presence of more neurons.
Spinal cord tapers off after lumbar enlargement.
Very bottom is called the conus medullaris (L2)
The long cord after that is called the terminal filum (filum terminali) that is not neural tissue but just anchors the cord

6. “The Heavenly Seven”

7. Nerve Roots Note the filum terminale that anchors the spinal cord.
The name for all the nerve fibers hanging down from the spinal cord is cauda equina. Means “the horses tail”

8. Nerve Roots and IV Discs
So herniation between L4 AND L5, the L5 nerve would be affected.
A hernation between C5 and C6 will affect C6 nerve

9. What is the most likely etiology for these findings?
A 18-year-old female presents with pain in her neck and in her right arm. Physical exam reveals pain along the lateral arm, involving the thumb. Grip strength is normal. Her upper limb reflexes on the right side are:
biceps = 1/4
brachioradialis = 0/4
triceps = 2/4
What is the most likely etiology for these findings?
CLINICAL CONCEPT
Muscle Strength is measured on a scale of 0 to 5.
> Normal strength is 5/5
> Paralysis is 0/5
Muscle Stretch Reflexes are measure on a scale of 0 to 4.
> Normal is 2/4
> PNS lesions are 0 or 1/4
> CNS lesions are 3 or 4/4
When reflexes are hypoactive indicates some damage to PNS or lower motor neurons
When reflexes are hyperactive it is a CNS problem or upper motor neuron problem.

10. Note the position of SPINAL CORD SEGMENTS relative to VERTEBRAL BODIES!
Student Dr. Spencer?
A compression fracture of the L2 vertebral body would most directly affect what level of the SPINAL CORD?
A. T12
B. L1
C. L2
D. L4
E. Cx1
In yellow is showing the level of the L3 SPINAL cord level.
There is a difference between where the vertebral body is in comparision to where it corresponds in the spinal cord.
Red is sacral spinal cord
Yellow is lumbar spinal cord.

11. Blood Supply to the Spinal Cord
Branches from the Vertebral Artery - Anterior and Posterior Spinal Arteries
Segmental Spinal Arteries
anterior radicular
posterior radicular
variable segmental medullary arteries
Only one anterior spinal artery. Goes all the way down.
Two posterior spinal artery
Segmental medullary arteries are feeder arteries that feed into posterior and anterior arteries.
Upper thoracic part doesn’t have a lot of feeder vessels.

12. Blood Supply to the Spinal Cord
The branches are coming off the aorta. Note the anterior spinal artery

13. Venous Drainage of the Spinal Cord
Intervertebral veins: follow arteries and nerves. They are draining spinal veins
Spinal Veins:
Internal Venous Plexus: communicates with the external spinal venous plexus
Venous Drainage of the Vertebral Column
External Spinal Venous Plexus:
Basivertebral Veins: they drain the vertebral bodies
Double arrow is internal venous plexus
Single arrow is intervertebral veins
On right they drain the vertebral veins. They have no valves. Meaning it can flow backwards. They freely anastamoses with other veins like the external venous plexus.
Basivertebral veins are also draining pelvic organs like the bladder, prostate. So this is how things can travel.

14. A 66-year-old male presents with the chief complaint of increased urinary frequency, back pain, lower limb weakness and numbness of two weeks duration. A digital rectal exam suggests prostate cancer. A gadolinium-enhanced MRI of the spine reveals:
Gadolinium is used to create a big contrast.
Guy has prostate cancer in those vertebrae b/c it metastasized
On right side of pic is vertebral veins. The pic just shows these veins are connected to other veins that circulate in body. Know as Batson’s plexus.

15. Think/Pair/Share
A 12-year-old male presents with the chief complaint of fever, headaches, nuchal rigidity, nausea and lethargy of two days duration. History and physical exam leads to the suspicion of meningitis.
You need to sample cerebrospinal fluid. Where is it?
What layers do you need to go through to sample CSF?
Where should you stick your needle?

16. Spinal Meninges
The spinal cord (in fact the entire CNS) is enclosed in three layers of tissue, the meninges.
The meninges are from external to internal:
Dura mater
Arachnoid mater
Pia mater
Dura mater- very tough and durable
Arachnoid- very thin like a spider’s web
Pia mater- is right on the spinal cord. Follows the exact shape of the spinal cord.

17. Spinal Meninges The dura mater:
is the outermost covering of the spinal cord
is a thick and dense inelastic membrane
is attached around the foramen magnum and bodies of the 2nd and 3rd cervical vertebrae
has tubular extensions for the roots of the spinal nerve as they pass thorough the IV foramen
Everything in blue is all dura.
Forms little sleeves around it.
The dura blends in with the epineurium covering.
Dura sac ends at S2 (but sleeves continue)

18. is between the dura and the periostium of the vertebrae
Spinal Meninges
The epidural space:
is between the dura and the periostium of the vertebrae
extends to the skull - fluids put into the sacral hiatus can spread to the base of the skull
The subdural space:
is a potential space between dura and the arachnoid that contains only a serous fluid
ends at the level of S2
The space outside the dura.
Epidural space goes from the sacrum all the way up to the skull.
Any fluids you put in the epidermal space could go all the way up to the skull
The subdural space is a potential space meaning usually it is empty. But things can accumulate there like pus, blood, blood cells.
Potential spaces can become REAL spaces when they fill with blood, air, etc.

19. Spinal Meninges
The arachnoid is a delicate membrane, that is separated from the dura by a potential subdural space. The arachnoid is not attached to the dura, but held to it by the normal pressure of CSF
The subarachnoid space:
is between the arachnoid and the pia
contains cerebrospinal fluid (CSF), blood vessels and connective tissue
surrounds the cord and spinal nerves, ends at the level of S2
The CSF is in the space between the arachnoid and pia mater known as the subarachnoid space

20. Spinal Meninges
The arachnoid is only loosely related to the underlying pia mater.
the spinal cord ends at L2
the dural sac and arachnoid end at S2
As a result there is a large space between the arachnoid and pia in the lumbar region:
Lumbar Cistern:
Sampling CSF:
Lumbar puncture and intracranial pressure:-
What about a newborn?
The space between L2 and S2 is known as the Lumbar Cistern. It is called this b/c it holds a lot of CSF. A lumbar puncture is done in this space.
What if someone has increased intracranial pressure due to hemorrhage or watever: you cant do a lumbar pucture b/c it will create a vacuum and suck the spinal cord down, damaging it.
Remember the newborn spinal cord is longer than an adult’s.
What if someone has some type of neural tube defect? You cant take it from the lumbar area. You can take it from another position right around the bottom of the skull

21. Lumbar Cistern

22. Lumbar Puncture
Do it midline between all the ligments

23. Spinal Meninges The pia mater:
faithfully invests the spinal cord and brain
is a vascular membrane (holds all the vessels like posterior and anterior spinal artery)

24. Spinal Meninges Denticulate ligaments:
continuous with the pia on the cord, between the dorsal and ventral roots
tooth-like process, 21 in number, stops at the T12 level
serves to stabilize the cord within the dura
Focus on number 9: it is an extension of the pia mater. It is a lateral extension. Is serrated.
Called denticulate ligaments (denticulate meaning teeth).
It surrounds the spinal cord and then it has these sheets of denticulate ligaments that connect to the dura mater to anchor and stabilize the spinal cord so it doesn’t move

25. Spinal Meninges The filum terminale:
is a fine filament of pia and connective tissue that descends from the conus medullaris
descends to the level of S2 where it is joined by dura (filum terminale internum)
descends to coccygeal levels and anchors the spinal cord in the dura sac (filum terminale externum)
Inside the dura it is called FTI.
And at the bottom it is pia and dura together. Known as filum terminale externum

26. Spinal Meninges Spinal block:
Epidural block: injecting anesthesia outside the dura
Spinal block or spinal anesthesia involves injecting anesthesia inside the dura and it is in contact with all the roots