Structure and fx of Spinal cord Flashcards
What is at bottom end of Spinal cord?
Narrows at L1 to form conus medullar is, and then caudal equine in lumbar cistern
Where does spinal cord start and end?
Cranial border of atlas to L1
What is the lumbar cistern?
contains auda equina (Lumbar and sacral dorsal and ventral roots)
In Lumbar cistern
What surrounds the spinal cord?
The meninges are continuous, even as spinal cord descends within vertebral column
Why do you do a lumber puncture low down?
below L1 in caudal equine area, so nerves can float out of the way, and spinal cord is not damaged
What are the 4 sections of the spinal cord
Cervical
Thoracis
Lumbar
Sacral
What does the Ventral root of a spinal nerve do?
Ventral root: efferent
How many paired spinal nerves are there?
31
How many cervical nerve pairs are there
8
How many thoracic nerve pairs
12
How many lumbar nerve pairs
5
How many scacral nerve pairs?
5
How many coccygeal nerves?
1
Where do C1 and C8 nerves come out?
C1 nerve comes out ABOVE C1 vertebra, below foramen magnum, C8 comes out below C8
Where are “conus medullaris is” and filum terminale externum”
“conus medullaris” end of spinal cord
hilum terminale externum” end of dural sac?
filum terminale internum: upper three quarters of the filum; covered by the spinal dura and arachnoid meninges. filum terminale externum: lower quarter of the filum; fuses with the investing dura mater and continues inferiorly to attach to the dorsal coccyx
The filum terminale (FT) is a fibrous band that extends from the conus medullaris to the periosteum of the coccyx, and its functions are to fixate, stabilize, and buffer the distal spinal cord from normal and abnormal cephalic and caudal traction.
What does the Ventral root of a spinal nerve do?
Ventral root: efferent
What are the spinal nerves for?
Connect periphery and spinal cord
What is the dorsal column pathway? (overview)
Describes how a sensation passes up the spinal cord, crosses in the medulla and then connects to somatosensory centre in the cortex via 3 neurons and various junctions
What is the internal structure of the spinal cord?
Inner core, grey matter
- Neuronal cell bodies
- H shaped
- Ventral, lateral and dorsal horns
Outer, white matter
- Myelinated axons
- White columns/tracts/funiculi
Where in the spinal cord is grey matter expanded?
Note expanded grey matter at levels that supply the limbs
What does the dorsal root of a spinal nerve do?
Dorsal root: afferent
How is the grey matter organised in the dorsal horn?
Dorsal horn - Neurons receiving sensory input
How is the grey matter organised in the lateral horn?
Lateral horn - Preganglionic sympathetic neurons
How is the grey matter organised in the ventral horn?
ventral horn - Motor neurons
(Also interneurons between/within levels)
what are laminae?
Layers of neurons in grey matter are called laminae
How is white matter organised in the spinal cord?
Myelinated axons
Run in bundles in specific tracts
Many tracts are named according to cell body of origin and where the axon terminates
Helps to aid learning of the different tracts
What does the Ventral root of a spinal nerve do?
Ventral root: efferent
How is sensations carried to brain?
Sensation is carried to the brain: afferent tracts
How are sensations carried?
Sensation is carried to the brain: afferent tracts
Tracts to and from the brain are crossed:
R side of brain controls L side of body
How are motor commands carried?
Motor commands come from the brain: efferent tracts
Tracts to and from the brain are crossed:
R side of brain controls L side of body
Which columns carry ascending and descending tracts?
Dorsal:
Lateral:
Ventral:
Dorsal column contains ascending tracts
Lateral column contains descending and ascending tracts
Ventral column contains mainly descending tracts
Which columns carry ascending and descending tracts?
Dorsal:
Lateral:
Ventral:
Dorsal column contains ascending tracts
Lateral column contains descending and ascending tracts
Ventral column contains mainly descending tracts