Spinal Cord Flashcards
How many pairs of spinal nerves are there ?
31 pairs of spinal nerves:
8 Cervical
12 Thoracic
5 Lumbar
5 Sacral
1 Coccygeal
What is the structure of the spinal cord meninges ?
Spinal cord meninges are continuous with the inner meningeal layer of the dura mater (and everything deep to it) from the level of the foramen magnum.
Spinal cord meningeal layers:
Vertebral canal (bone)
Extradural space
Exists as an actual space, and contains blood vessels and extradural fat.
Dura mater
Arachnoid mater
Subarachnoid space
Pia mater
Has longitudinal projections/folds extending laterally – denticulate ligaments. These help to position the spinal cord centrally.
Spinal cord
What are the two enlargements of the spinal cord?
Cervical enlargement
Lumbar/Lumbosacral enlargement
What is a caudia equina ?
After spinal cord ends, the lumbar cistern extends until the dural sac ends.
Nerves continue in this region and are known collectively as cauda equina.
Why is the lubar sistern clinically relevatn ?
The CSF in this area is the same as within the brain.
Therefore, taking a lumbar sample from the lumbar space can confirm an infection within the brain.
What is the Filum terminale ?
Filum terminale extends from conus medullaris to attach onto the coccyx.
Anchors the spinal cord inferiorly.
Has a pial part (from pia mater) and then a dural part (from dura mater when dural sac ends).
What are dermatomes ?
Each spinal nerve supplies the body.
e.g. injury to the heart
Explain the cross-sectional structure of the spinal cord.
Cross-section of spinal cord at any level is roughly H-shaped – the H being formed by gray matter.
In a cross section:
Gray matter
Divided into horns – usually anterior and posterior
Lateral horn exists in thoracic region (T1-L2)
Also known as intermediolateral cell column
White matter
Divided into funiculi – anterior, lateral, and posterior.
Central canal
Filled with CSF.
Grooves/fissures:
Anterior median fissure
Posterior median sulcus
Posterolateral sulci (on each side)
What is the white matter or the spinal cord divided into ?
White matter
Divided into funiculi – anterior, lateral, and posterior
What is the grey matter of the spinal cord divided into?
Divided into horns – usually anterior and posterior
Lateral horn exists in thoracic region (T1-L2)
What do neutrons do the different parts of the gray matter do ?
Ventral/anterior horns contain motor neurons – efferent fibres.
Dorsal/posterior horns contain sensory neurons – afferent fibres.
What is rexed lamina
Gray matter can be further divided into 10 zones – Rexed’s laminae I-X
Does the amount of grey matter vs white matter differ throughout the spinal cord?
YES
What part of the white matter contains motor neurone and which has sensory nuerons?
White matter
Anterior funiculus contains motor neurons.
Posterior funiculus contains sensory neurons.
Explain spinal nerve
Each spinal nerve is formed by both sensory and motor innervation.
The spinal cord is divided functionally into segments – these are the points where spinal nerves form from.
To spinal cord dorsal horn (sensory):
Sensory information travels along spinal nerve and splits just before spinal ganglion.
Spinal ganglion becomes posterior/dorsal root.
Dorsal root divides into posterior/dorsal rootletts
From spinal cord ventral horn (motor):
Motor information travels along anterior/ventral rootlets to form anterior/ventral root.
Combines with dorsal root after spinal ganglion to form spinal nerve.
A spinal nerve then splits into a posterior and anterior ramus (plural. rami).
Posterior rami usually innervate back muscles and back skin.
Anterior rami most other skeletal muscle and skin.
What is the blood supply to the spinal cord
Anterior spinal artery Posterior spinal chord
Segmental
What is the venous drainage of the spinal cord.
Anterior spinal vein
Posterior spinal vein
