Spinal Cord
Spinal Cord:
• The spinal cord is an elongated, approximately
cylindrical part of the CNS, occupying the
superior twotwo-thirds of the vertebral canal. Its
average length is 45 cm, its weight c.30
c.30 g .
• The spinal cord is the major reflex center and
conduction pathway between the body and the
brain.
Spinal Cord:
• It is protected by the vertebrae and their
associated ligaments and muscles, the spinal
meninges, and the cerebrospinal fluid (CSF).
• The spinal cord begins as a continuation of the
medulla oblongata ,(the caudal part of the
brainstem. It extends from the upper border of
the atlas to the junction between the first and
second lumbar vertebrae.
Spinal Cord:
• The cord narrows caudally to the conus
medullaris, from whose apex a connective
tissue filament, the filum terminale,
descends to the dorsum of the first
coccygeal vertebral segment .
Superior
Dorsal view of lower vertebral levels
of spinal cord and conus medullaris
Dorsal root of
spinal nerve
Ventral root of
spinal nerve
Spinal cord
Conus medullaris
Inferior
Filum terminale
Cauda equina:
Dorsal and ventral roots of lower
lumbar and sacral spinal nerves
Spinal cord enlargements :
• The spinal cord is enlarged in two regions in
relationship to innervation of the limbs.
• The cervical enlargement extends from the C4
C4 through
T1 segments of the spinal cord, and most of the
anterior rami of the spinal nerves arising from it form
the brachial plexus of nerves that innervates the
upper limbs.
• The lumbosacral (lumbar) enlargement extends from
T11 through S1
S1 segments of the spinal cord, The
anterior rami of the spinal nerves arising from this
enlargement make up the lumbar and sacral plexuses
of nerves that innervate the lower limbs
Spinal Cord In Vertebral Column:
Lateral View
C1 spinal nerve
Spinal
Nerve Level
Cervical
Cervical
enlargement
Cervical +
lumbosacral
enlargements:
-Enlarged regions
of cord that
contribute to
massive
innervation of
upper and lower
extremities
T1 spinal nerve
Thoracic
Lumbosacral enlargement
T12 spinal nerve
Lumbar
L1 spinal nerve
Sacral
Conus medullaris
Cauda equina
L5 spinal nerve
S1 spinal nerve
S5 spinal nerve
Spinal Cord:
• Fissures and sulci extend along most of
•
the external surface.
An anterior median fissure and a posterior
median sulcus and septum almost
completely separate the cord into right
and left halves, but they are joined by a
commissural band of nervous tissue which
contains a central canal .