Spinal Cord Flashcards
what is the segmentation of the spinal cord
- Cervical – 8 (but 7 cervical vertebrae bones) o Thoracic – 12 o Lumber – 5 o Sacral – 5 o Coccygeal – 1
total segments- 31
Each segment gives rise to a _____ of spinal nerves
pair
What is the lower limit of the spinal cord in adults and infants
New born infants- L3/L4 vertebrae
Adults- L1/L2 border
describe the passing of spinal nerves in relation to their vertebrae
C1-7 pass through the intervertebral foramen above their vertebrae
C8 – Coc1 pass through the intervertebral foramen below their vertebrae
what is the upper limit of the spinal cord
at junction with the medulla oblongota of the brainstem
what embryological sturcure is the spinal cord formed by
Neural Tube
how is neural tube formed
develops from a flat plate of cells called
the neuro-ectoderm
how is a tube of neuroectoderm formed
Edges of plate rise up and meet each other in midline- forming a central canal
WHat is the central canal of the neuroectoderm tube surrounded by
nervous tissue (grey and white matter)
The neural tube has two different plates of cells. what does the alar plate form
Dorsal grey matter (sensory)
What does the basal plate form
Ventral grey matter (motor)
how does spina bifida occurs
due to the failure of neural tube closure in the caudal area
Describe the types of spina bifida severities
- Occulta- least severe with no outwards sign
- Lipo-meningocele- spinal cord attached to fatty growth- can be outward signs
- Meningocele
- Myelomeningocele
Both 3 and 4 can be severely affected by paralysis, loss of sensation and other defects below level of deformity
what does the grey matter of the spinal cord include
Dorsal Horn
Intermediate Horn
Ventral Horn
Transverse section- grey matter is towards the central part of the spinal cord
(see pics)
what does the white matter of the spinal cord include
Dorsal Funiculus
Lateral Funiculus
Ventral Funiculus
Transverse section- white matter is towards the peripheral part of the spinal cord
(see pics)
what occurs in the grey matter areas
Dorsal Horn- sensory function
Intermediate Horn- Autonomic function
Ventral Horn- Motor function
what occurs in the white matter areas
Dorsal Funiculus- involved in ascending pathway
Lateral Funiculus- contains the lateral corticospinal and rubrospinal tracts
Ventral Funiculus- involved in pain and temperature pathways
whats the difference between the sizes of the grey matter in the spinal cord segmentations and why
Cervical and lumber regions have a larger ventral grey matter region compared to sacral and thoracic because they supply the musculature of the limbs and require finer control of movements.
describe the spinal cord segmental innervation
Cervical- upper limb
Thoracic- Thorax
Lumbar- lower limb
Sacral- genital area
Describe the dura mater layer of the meninges in the spinal cord
- Outer meningeal layer – thick inelastic membrane
- Fuses with the endosteum of the cranium at the foramen magnum (opening that connects spinal cord to brain)
- Space between dura mater and vertebral endosteum is the epidural space (epidural space has fat and blood vessels)
What is the difference between spinal cord and brain dura mater
Brain: Dura has 2 layers: - Outer periosteal layer - Inner meningeal layer No epidural space between periosteal layer and the cranium- epidural space only exists when pathology occurs e.g. epidural haematoma (blood collects in the space)
Spinal Cord:
Dura has 1 layer: outer meningeal layer
Epidural space exists between vertebrae and meningeal layer even without pathology. Normal epidural space contains fat and blood vessels
Describe the arachnoid mater layer of the meninges in the spinal cord
- Middle meningeal layer – thin fibrous membrane
- Space between arachnoid mater and pia mater is the subarachnoid space which contains CSF
- Contains trabeculae which go to the pia mater
Describe the pia mater layer of the meninges in the spinal cord
- Innermost meningeal layer – unicellular membrane
surrounding the spinal cord - Quite vascularised
- Pair of denticulate ligaments (one each side) with 21
attachments laterally to the arachnoid mater - Separated from the spinal cord by the subpial space
what is the CSF and what are its functions
A filtrate of blood
Affords mechanical and immunological protection to the brain and spinal cord
Describe the production and reabsorbtion of the CSF
Made in the choroid plexus within the ventricular system of the brain
Produced around 500 ml each day
About 140ml circulates throughout the subarachnoid space
Reabsorbed into the venous drainage system of the head
Describe the venous drainage of the spinal cord
3 ANTERIOR AND 3 POSTERIOR VEINS WHICH FORM THE:
Posterior and anterior internal and external venous plexus
where is the venous drainage found in
Venous drainage found in the epidural space
Why is the Batson venous plexus a major route for metastasis
The Batson venous plexus is major route for metastasis of cancer from deep pelvic regions since they are valveless
what is the arterial supply of the spinal cord
Supplied by:
2 posterior spinal arteries:
- Forms from vertebral artery or posterior-inferior cerebellar artery
- Anastomose
1 anterior spinal artery:
- Forms from branches of vertebral artery – arises from
brachiocephalic artery
-Lies in anterior median fissure
what does artery of adamkiewicz supply and what does it arise from
supplies lower 1/3 of the spinal cord
typically arises from left posterior intercostal artery
what is the clinical signifcance of the artery of adamkiewicz
loss of urinary and/or faecal continence
impaired motor function of legs/ spasticity
what is the conus medullaris
tapered most inferior part of the spinal cord near L1/2
what is the cauda equina
is the bundle of spinal nerve and spinal nerve rootlets from L1/2-L5 which arises from the conus medullaris
what is the filum terminale
a strand of fibrous connective tissue which anchors the conus medullaris to the coccyx
what is the lumbar cistern
subarachnoid space in the lower lumbar spinal canal
Cistern is an enlargement of the subarachnoid
space distal to the conus medullaris
what is the lumbar cistern site of and at what vertebral level does this occur
site for epidural injections and lumbar punctures
L3/4 or L4/5 vertebral level
what are the uses of epidural and lumbar puncture
Epidural Injections use:
- Administration of anaesthetics
Lumbar punctures use: o Diagnostic: - Withdraw CSF - Measure CSF - Pressure
o Therapeutic:
- Administration route for antibiotics or chemotherapy
what level is iliac crest at?
L4
