Anatomy of the spinal cord Flashcards
Spinal cord location
Spinal cavity within the vertebrae
starts at the foramen magnum
ends at the inferior border of the 1st lumbar vertebra
Spinal cord surroundings
sits within a fibrous sac made of meninges, inside the spinal cavity
Non-neural structures associated with the spinal cord (3)
- meningeal sac filled with cerebrospinal fluid (CSF)
- conus medularis, tapered cone-like end
- filum terminale
Meningeal sac
- what the spinal cord is extended in
- filled with CSF
- provides a liquid cushion around the spinal cord to protect it from injury
Conus medularis
tapered cone-like end of the spinal cord
Filum terminale
- extends from the conus medularis to the end of the spinal cavity
- anchors the spinal cord
- made of fibrous, non-neural tissue
8 pairs of ______ spinal nerves
cervical
12 pairs of _____ spinal nerves
throacic
5 pairs of _____ spinal nerves (upper)
lumbar
5 pairs of _____ spinal nerves (lower)
sacral
1 pair of _____ spinal nerves
coccygeal
Cauda Equina
large collection of nerves inferior to the end of the spinal cord. these nerves have to grow more to exit the spinal cord at the right vertebra
Spinal nerves are named by the vertebra they exit below, with the one exception being…
the first cervical spinal nerve exits between the skull and the first cervical vertebra. there are 8 cervical spinal nerves but only 7 cervical vertebrae
2 spinal cord indentations
- posterior median sulcus
- anterior median fissure
‘H’ shaped mass is made of
grey matter (cell bodies)
Surrounding the grey matter is
white matter (bundle of axons that run the length of the spinal cord)
CNS features of the spinal cord
- grey matter
- white matter
- dorsal horn
- dorsal column
- ventral horn
- lateral horn
- lateral column
PNS features of the spinal cord
- nerve roots (axons)
- ganglions (cell bodies)
- dorsal nerve roots
- dorsal root ganglions
- ventral nerve rootS
Information flow:
Dorsal side of spinal cord
sensory (afferent)
Information flow:
Dorsal nerve roots
axons conduct information from PNS into CNS
Information flow:
Ventral side of spinal cord
motor (efferent)
Information flow:
Ventral nerve root
axons conduct information from CNS into PNS
Flow of afferent information:
into the spinal cord (3 steps)
- cell bodies of sensory neurons are in dorsal root ganglion
- input zone in body associates with receptors for sensory stimulus
- output zone enters the spinal cord through dorsal roots
Spinal nerve branches:
Dorsal ramus
carries efferent information to the back and afferent information from the back
Spinal nerve branches:
Ventral ramus
carries efferent information to the front and afferent information from the front
Spinal nerve branches:
Rami communicans
sympathetic, only at T1 - L2
only carries information to and from the sympathetic ganglion
Structure of a peripheral nerve (6 features)
- individual axons may be myelinated (shown) or unmyelinated (not shown)
- axons are covered with endoneurium
- endoneurium-covered axons are bundled together to form a fascicle
- fascicles are covered in perineurium
- fascicles bundle with each other and with blood vessels to form a nerve
- nerves are covered by epineurium
