Central Nervous System:“CNS”Spinal CordBrainCentral Nervous System: Notes | EduRev

: Central Nervous System:“CNS”Spinal CordBrainCentral Nervous System: Notes | EduRev

 Page 1


Central Nervous System:
“CNS”
Spinal Cord
Brain
Page 2


Central Nervous System:
“CNS”
Spinal Cord
Brain
The Spinal Cord
? Foramen magnum to L1 or L2 
? Runs through the vertebral canal of the 
vertebral column
? Functions
1. Sensory and motor innervation of entire body 
inferior to the head through the spinal nerves
2. Two-way conduction pathway between the body 
and the brain
3. Major center for reflexes
Page 3


Central Nervous System:
“CNS”
Spinal Cord
Brain
The Spinal Cord
? Foramen magnum to L1 or L2 
? Runs through the vertebral canal of the 
vertebral column
? Functions
1. Sensory and motor innervation of entire body 
inferior to the head through the spinal nerves
2. Two-way conduction pathway between the body 
and the brain
3. Major center for reflexes
? Fetal 3
rd
month: ends at 
coccyx
? Birth: ends at L3
? Adult position at approx  L1-2 
during childhood
? End: conus medullaris
? This tapers into filum terminale
of connective tissue, tethered 
to coccyx
? Spinal cord segments are 
superior to where their 
corresponding spinal nerves 
emerge through intervetebral 
foramina (see also fig 17.5, p 
288)
? Denticulate ligaments: lateral 
shelves of pia mater anchoring 
to dura (meninges: more later) 
Spinal cord
http://www.apparelyzed.com/spinalcord.html
Page 4


Central Nervous System:
“CNS”
Spinal Cord
Brain
The Spinal Cord
? Foramen magnum to L1 or L2 
? Runs through the vertebral canal of the 
vertebral column
? Functions
1. Sensory and motor innervation of entire body 
inferior to the head through the spinal nerves
2. Two-way conduction pathway between the body 
and the brain
3. Major center for reflexes
? Fetal 3
rd
month: ends at 
coccyx
? Birth: ends at L3
? Adult position at approx  L1-2 
during childhood
? End: conus medullaris
? This tapers into filum terminale
of connective tissue, tethered 
to coccyx
? Spinal cord segments are 
superior to where their 
corresponding spinal nerves 
emerge through intervetebral 
foramina (see also fig 17.5, p 
288)
? Denticulate ligaments: lateral 
shelves of pia mater anchoring 
to dura (meninges: more later) 
Spinal cord
http://www.apparelyzed.com/spinalcord.html
Spinal nerves
? Part of the 
peripheral 
nervous 
system
? 31 pairs attach 
through dorsal 
and ventral 
nerve roots
? Lie in 
intervertebral 
foramina
Page 5


Central Nervous System:
“CNS”
Spinal Cord
Brain
The Spinal Cord
? Foramen magnum to L1 or L2 
? Runs through the vertebral canal of the 
vertebral column
? Functions
1. Sensory and motor innervation of entire body 
inferior to the head through the spinal nerves
2. Two-way conduction pathway between the body 
and the brain
3. Major center for reflexes
? Fetal 3
rd
month: ends at 
coccyx
? Birth: ends at L3
? Adult position at approx  L1-2 
during childhood
? End: conus medullaris
? This tapers into filum terminale
of connective tissue, tethered 
to coccyx
? Spinal cord segments are 
superior to where their 
corresponding spinal nerves 
emerge through intervetebral 
foramina (see also fig 17.5, p 
288)
? Denticulate ligaments: lateral 
shelves of pia mater anchoring 
to dura (meninges: more later) 
Spinal cord
http://www.apparelyzed.com/spinalcord.html
Spinal nerves
? Part of the 
peripheral 
nervous 
system
? 31 pairs attach 
through dorsal 
and ventral 
nerve roots
? Lie in 
intervertebral 
foramina
Spinal nerves continued
? Divided based on vertebral locations
? 8 cervical
? 12 thoracic
? 5 lumbar
? 5 sacral
? 1 coccygeal
? Cauda equina (“horse’s tail”): collection of nerve 
roots at inferior end of vertebral canal
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