The central nervous
system
the spinal cord
Xiaoming Zhang
Department of Human Anatomy
School of Medicine
Zhejiang University
The Spinal Cord
1. External features:
 Location:
foramen magnum -- lower
border of first lumbar vertebra
 Shape:
A long cylindrical structure
 Enlargements:
cervical enlargement
lumbar enlargement
 Conus medullaris
 Filum terminale
• main longitudinal fissure and sulci on surface:
Cauda equina
posterior lateral
posterior median sulcus
sulcus
Filum terminale
anterior lateral
sulcus
anterior median
fissure
• Spinal segment:
It's a part of spinal cord, which is connected
with the rootlets of a pair of spinal nerve.

31 segments
8 cervical segments
12 thoracic segments
5 lumbar segments
5 sacral segments
1 coccygeal segments

Corresponding relationship between
spinal segments and vertebrae
spinal segments
C1-C4
C5 ~ T8, T l~ T4
correspond to vertebrae
C1-C4
C4 - C7, C7 ~ T3
T5 ~ T8
T3 ~ T6
T9-T12
T6-T9
L1-L5
T10-T12
S l~S5,Co1
LI
2. Internal structure
 The central canal
central canal
 Gray matter:
 parts:
 Lateral horn
(only extends from Tl
posterior horn
Intermediate
zone
Lateral horn
to L3 segments.)
 gray
commissure
(anterior and
posterior )
anterior horn
Gray matter
gray commissure
 Main
nuclei:
anterior horn:
medial group
lateral group
intermediate zone:
intermediolateral nucleus
intermediomedial nucleus
the nucleus
posteromarginalis
the substantia
gelatinosa
the nucleus proprius
the dorsal nucleus
(thoracic nucleus)
posterior horn:
the nucleus
posteromarginalis
the substantial gelatinosa
the nucleus proprius:
the dorsal nucleus
(thoracic nucleus)
intermediolateral
nucleus
Intermediomedial
nucleus:
lateral group
medial group
The nuclei and the laminas
the nucleus
posteromarginalis
the substantia
gelatinosa
the nucleus proprius
the dorsal nucleus
(thoracic nucleus)
intermediolateral
nucleus
Intermediomedial
nucleus:
lateral group
medial group

White matter:
 parts:
posterior median sulcus
posterior funiculus
posterior lateral sulcus
lateral
funiculus
anterior lateral sulcus
anterior white
commissure
anterior median
fissure
anterior funiculus
 Main
tracts (or fasciculi):
long ascending tracts:
 fasciculus gracilis: come from sacral,
lumbar and lower six thoracic nerves,
terminate upon nucleus gracilis
 fascicules cuneatus: come from
cervical and upper six thoracic nerves,
terminate upon nucleus cuneatus.
 *conduct the fine tactile (e.g.two-point
 discrimination) and kinesthetic sense
(e.g.position and movement and
vibration)of the ipsilateral trunk and
limbs.
fascicules
cuneatus
fascicules
gracilis

lateral and anterior spinothalamic
 tracts:
 *in corresponding funiculus
 *arises from opposite nucleus
proprius
 *terminate on thalamus
 *conduct pain, thermal and
rough tactile sense of opposite
trunk and limbs
thalamus
anterior
spinothalamic
tracts
anterior
spinothalami
c
tracts
nucleus proprius
 main
long descending tracts
lateral corticospinal tract:
*arises from opposite cerebral
cortex
*descends through lateral
funiculus of spinal cord
*terminate on ipsilateral
anterior horn (lateral group)
*controls the contraction of
skeletal muscles of ipsilateral
limbs
anterior corticospinal tract:
*controls the movement of
bilateral muscles of trunk
lateral
corticospinal
tract
anterior
corticospinal
tract
Other descending tracts:
they are related to regulate muscle tonus
Fascicules gracilis
fascicules cuneatus
lateral
corticospinal
tract
Rubrospinal
tract
anterior
spinothalami
c
tracts
Reticulospinal
tract
anterior
spinothalamic
tracts
vestibulospinal
tract
tectospinal tract
anterior corticospinal
tract

Functions:
•
To convey afferent impulses, which come from
somatic and visceral receptors to the brain, and
conduct efferent impulses from brain to effectors.
•
Related to reflexes