Neuroanatomy Flashcards
filum terminale
- extends from conus medullaris to the posterior surface of the coccyx
- made from pia mater
- anchors the spinal cord
Cauda equina
- “Pony tail”
- after birth the vertebral column grows faster than spinal cord
- have to grow axons down to where they can exit (from lateral appeture)
Cross section of spinal cord
- white matter peripheral
- grey matter central (butterfly) [opposite to brain]
- anterior median fissure
- posterior median sulcus
things that come off the spinal cord
- Dorsal roots = afferent (sensory input)
- ventral root = efferent fibres (motor output)
- combine to make spinal nerve = 2 way info
Spinal Cord Injury - where causes what?
- C1-C4 = high tetraplegia (no arms or legs)
- C5-C8 = low tetraplegia (no legs, some arms)
- Thoracic, lumbar or sacral injuries = paraplegia (arms but no legs)
Dura mater - function and layers
- provides main protection and support
- in two layers
- periosteal layer (next to the bone)
- meningeal layer
- folds and extends inwards to for flat partitions
- subdivide the cranial cavity
- limit excessive movement of the brain within the cranium
- seperates in places to form venous sinuses (big veins) to drain blood
Folding of menigial layers
- forms a partition between:
- two cerebral hemispheres = falx cerebri
- cerebellum & cerebrum = tentorium cerebelli
- two cerebellar hemispheres (runs along the midline) = Falx cerebelli
space between meningeal dura mater & arachnoid mater
Subdural space
- very narrow, contains a film of fluid
- may be enlarged by bleeding = subdural hemorrhage
arachnoid mater
- much more delicate than dura
- doesn’t follow sucli
- connected to the pia mater by fine strands of connective tissue (arachnoid trabecula)
Subarchnoid space
- cushion of CSF around the brain
- a barrier between soft brain tissue and hard skull
- contains blood vessels, not super protected
- if severe head knock → bleeding into CSF = subarachnoid haemorrhage
Arachnoid villi
- projections of arachnoid matter
- a collection = arachnoid granulations
- cauliflower like structures
- for draining CSF into venous sinuses
Cistern (and the biggest one)
= enlarged subarachnoid space (like in the spaces between brain structures)
biggest = Cisterna Magna (Cerebellomedullary
Cistern)
Pia matter
- follows contours of the brain
- surrounds blood vessel
- Helps form the roof of the ventricles, closely associated with choroid plexus and ependyma
Spinal meninges - dura
- only the menigenal layer, no periostial layer
- because need more mobility for body
- epidural space between dura and verterbal wall
- Contains fat tissue & venous plexus
- largest at L2
- epidural anaesthesia here
subarachnoid space - spinal cord
- Between the arachnoid and pia mater meninges
- Contains CSF
- cushions/protects spinal cord
Lumbar Cistern
subarachnoid space inferior to spinal cord (below L1)
- Lumbar puncture (sampling of CSF)
CSF circulation
chorid plexus → lateral ventricles → 3rd ventricle → cerebral aqueduct → 4th ventricle → median appeture → subarachnoid space → arachnoid vili → superior saggital sinus
Occlusion to anterior cerebral artery =
contralateral hemiplegia (one artery) or bilateral
paralysis (two arteries) & impaired sensation
- greatest in lower limb
Occlusion to middle cerebral artery =
- a severe contralateral hemiplegia & impaired sensation
- most marked in the upper limb & face
- severe aphasia (if the dominant hemisphere is affected)
Occlusion to posterior cerebral artery =
contralateral homonymous hemianopsia
describe venous drainage from brain to heart
fine veins in grey matter → pial venous plexuses = associated with pia → cerebral veins drain into sinuses → joined by blood from veins in scalp via emissary veins
→ venous sinuses = large veins (there’s lots of these we need to know → internal jugular vein
