Spinal Cord Flashcards
Paralysis following spinal cord injury
Where does the spinal cord begin
What is it continuous with at its origin
Begins at foramen magnum
Continuous with medulla
Diameter and length of the spinal cord
Diameter = 1-1.5cm
Length = 45cm
Hence occupies upper 2/3rd of vertebral canal of vertebral column
Where does the spinal cord terminate in
- Adults
- Children
Why does the spinal cord terminate before the vertebral column
- L1-L2 in adults
- Near L3 in young child
Rate of growth of bone (vertebral column) tissue is faster than the rate of growth of nerve tissue
Hence lumbar cistern below termination point
How the 3 meningeal layers transfer to spinal cord
What anchors the spinal cord in its position
Denticulate ligament
A continuation of pia mater
Name and indentify where there are enlargements in the spinal cord
- Cervical enlargement - origin to brachial plexus (C3-T2)
- Lumbar enlargement - origin to lumbosacral plexus (L1-S3)
Name the most inferior structure of the spinal cord
Spinal cord tapers off into CONUS MEDULLARIS
What is the cauda equina
Extension of bundle of nerve roots beyond the cord
What is the filum terminale
A prolongation of pia mater
Descends from conus medullaris to attach to coccyx (anchor)
Dissections of conus medullaris, cauda equina, meningeal layers and filum terminale
What opening do nerves pass through
Intervertebral foramina
Transverse section of spinal cord
How to distinguish the dorsal (sensory) root from the ventral (motor) root
Sensory ganglia - swelling
* Dorsal root ganglion
Dorsal/posterior roots are _______
Sensory
Ventral/anterior roots are ________
Motor
How is each root attached to the cord
By a series of rootlets
What does the spinal nerve branch into
Anterior/ventral ramus
Posterior/dorsal ramus
Series of smaller branches
Transverse process of spinal cord & spinal nerve branches
What is the dermatomal map
Each spinal nerve carries sensory information for a part of the body surface
Sensation lost in 1 dermatome only when approx 3 adjacent roots have been injured, hence there is a compensatory effect
What do afferent nerve fibres do
Bring information to the spinal cord which then travels up to the brain
What do efferent nerve fibres do
send information from the spinal cord out along nerves
Transverse section of spinal cord
Note - grey matter is at the centre, white matter at the surface edge
What lines the central canal
Ependymal cells
What happens if the fluid in the 4th ventricle does not drain down to the central canal
It goes to the 3 apertures in the roof of the 4th ventricle
Divisions of grey matter
Dorsal/posterior column
Ventral/anterior column
Lateral column (intermediate zone)
Rexed’s laminae - 10 zones
Where is true lamination confined to
Dorsal horn
What is the substantia gelatinosa in the dorsal grey column
Apex of dorsal grey column throughout cord length
Receives afferents related to pain, temperature, touch from dorsal root
What is the nucleus proprius in the dorsal grey column
Ventral to substantia gelatinosa throughout the length
Receives fibres from dorsal white columns
Senses of position, movement (proprioception)
What is the nucleus dorsalis/Clarke’s column in the dorsal grey column
Base of dorsal grey column
C8 - L3/4 segments
Proprioceptive signals - cells give rise to posterior spinocerebellar tract
What do the nerve cell groups in ventral gray columns do
Cell columns of lower motor neurons in ventral grey matter supply groups of muscles with similar functions
Difference between monosynaptic and polysynaptic
What is the amount of grey matter present proportional to
The amount of muscle innervated at that level
Define the 3 divisions of white matter
- Anterior/ventral funiculus - between anterior median fissure and anterolateral sulcus
- Lateral funiculus - between anterolateral sulcus and posterolateral sulcus
- Posterior/dorsal funiculus - between posterolateral sulcus and dorsal median sulcus
What do the ascending tracts of white matter carry impulses from
Pain
Tactile, thermal, muscle and joint receptors
=> exteroeceptive and proprioceptive info
What are the descending tracts of white matter involved in
Define their path
Descend down from cerebral cortex and brain
Involved in control of movement, posture, muscle tone
Define intersegmental tracts
Fibres carry info from 1 segment to another
Important intersegmental spinal reflexes
What are the principle fibre tracts of the spinal cord
Name the 3 arteries that supply the spinal cord
Anterior medial spinal artery
2 x smaller posterior spinal arteries
Where is the anterior median spinal artery located
How much of the blood supply does it constitute
Located along the anterior midline of the cord
Supplies most (75%) of the arterial blood supply to spinal cord
Where are the smaller posterior spinal arteries located
How much of the blood supply do they constitute
Lie on each side of the cord posteriorly
Supplies only 25% of the arterial blood supply to posterior region of spinal cord
Origin of the posterior spinal arteries
Directly from vertebral spinal arteries or INDIRECTLY from posterior inferior cerebellar arteries
Origin of anterior spinal artery
Formed by union of the 2 branches of the vertebral arteries
Veins of the spinal cord
Drain into 6 longitudinal channels
- Anterior spinal v.
- Posterior spinal v.
- Anterolateral v.
- Posterolateral v.
=> into anterior and posterior radicular veins
- Radicular veins drain into internal vertebral venous plexus
