Spinal Cord
Dr Rania Gabr
Objectives
• Describe the gross anatomical features of the
spinal cord.
• Describe the level of the different spinal
segments comparing to the level of their
respective vertebrae.
• Identify important gross features of spinal cord,
nerve roots, and spinal ganglia.
• Describe the internal features of spinal cord (gray
matter and white matter) in the different regions.
Vertebral
Column
Vertebral Column
• Consists of vertebrae and
the intervening discs.
• It appears as straight line
anteroposteriorly, and with
multiple curves laterally
• According to shape and
location, vertebrae can be
divided into:
 Cervical (7)
 Thoracic (12)

Lumbar (5)

Sacral (5 Fused )

Coccyx ( 4 Fused)
Nervous system
Central nervous system
 Brain
 Spinal cord
Peripheral nervous system
 12 pairs of cranial nerves
 31 pairs of spinal nerves
Structure of the Spinal Cord
• A cylinder of gray &
white matter
• In the upper 2/3 of
vertebral canal
• Extends From foramen
magnum to L1 (or L2)
• Covered with meninges
& CSF
• A typical adult spinal
cord ranges between 42
and 45 centimeters
.
The Spinal Cord
 The spinal cord is associated
with 31 pairs of spinal nerves
that connect the CNS to
muscles, receptors, and
glands.
 Each side of the spinal cord
contains :





8 Cervical nerves (C1-C8)
12 Thoracic nerves (T1-T12)
5 Lumbar nerves (L1–L5)
5 Sacral nerves (S1–S5),
1 Coccygeal nerve
Structure of the Spinal Cord
• The spinal cord is shorter than the
vertebral canal that houses it.
Extends only to L1/ L2
• Has two enlargements, cervical &
lumbar due to cells and fibers of
limbs.
• Ends inferiorly in a tapering
conus medullaris
• Anchored to the coccyx by
a meningeal ( non neuronal)
extension (filum terminale)
• Held to dura by denticulate
ligament
• a
• The cervical enlargement
consists of cord segments
C3-T1 and provides
innervation for the upper limb via
the brachial plexus.
• The lumbar enlargement is
made up of segments L1-S3
and is associated with
innervation of the lower limb
via the lumbar plexus (L1-L4)
and the sacral plexus (L4-S2)
The Spinal Cord
Provides a vital link between the brain and
the rest of the body.
Exhibits some functional independence from
the brain.
The spinal cord and its attached spinal
nerves serve some important functions :-
Functions of the Spinal Cord
• Receives afferent fibers from sensory receptors
of the trunk and limbs
• Controls movements of the trunk and limbs
• Provide autonomic innervation for most of the
viscera.
• Responsible for many loop reflexes
• It conveys afferent information to higher centers
and mediate their controlling influence over
spinal mechanisms.
Spinal Meninges
• Are continuous with the cranial meninges.
• Structures that encircle the spinal cord, listed from
outermost to innermost are:
1-vertebra
2-epidural space: Contains blood vessels, areolar
connective tissue and fat.
3-dura mater
4-subdural space: a potential cavity between the dura and
arachnoid mater, contains a small volume of serous fluid
5-arachnoid
6-subarachnoid space: Contains cerebrospinal fluid (CSF)
and blood vessels
7-pia mater
Meninges of Spinal Cord
Surfaces
• Surface marked by furrows
• A deep ventral (anterior)
median fissure
• A dorsal (posterior)
median sulcus
• 2 dorsolateral &
2 ventrolateral sulci
• 2 dorsal intermediate sulci
Cross Section of Spinal Cord
Anterior median fissure and
posterior median sulcus
– deep clefts partially
separating left and right
halves
Gray matter: neuron cell bodies,
dendrites, unmylinated axons
– Divided into horns
• Posterior (dorsal) horn
• Anterior (ventral) horn
• Lateral horn only in
The intermediate zone
thoracic, lumbar and sacral.
traversed by Central Canal.
Relation of Spinal Nerve with Vertebral Column
White matter
– Myelinated axons
– Divided into three columns (funiculi)
• Ventral
• Dorsal
• lateral
– Each of these divided into sensory or motor tracts
Commissures: connections between left and right halves
– Gray with central canal in the center
– White
Roots
– Spinal nerves arise as rootlets then combine to form
dorsal and ventral roots
– Dorsal and ventral roots merge laterally and form the
spinal nerve
Spinal Cord (White Matter)
Grey matter
• Consists of nerve cell bodies and their processes, neuroglia, and blood
vessels
• The nerve cells are multipolar and are of three main categories:
1. Sensory neurons (Tract cells), which receive impulses from the
periphery of the body and whose axons constitute the ascending
fasciculi of the white matter, are located in the dorsal horns
2. Lower motor neurons, which transmit impulses to the skeletal
muscles, are located in the ventral horns (similar neurons in the
lateral horn are the preganglionic neurons of the autonomic
system)
3. Interneurons (connector neurons) : linking sensory and motor
neurons, at the same or different levels, which form spinal reflex
arcs.
• Different cord levels vary in
the relative amounts and
configuration of grey and
white matter.
• Higher levels contain greater
amounts of white matter.
• Why?
• Because ascending tracts gain
fibres at each successive level,
whereas the opposite is true
of descending tracts.
• The size and shape of the dorsal
and ventral horns varies
according
to the level.
• Both dorsal and ventral horns
are,
therefore, particularly well
developed at cervical and lumbar
levels in association with
innervation of the upper and
lower limbs.
Sections through spinal cord at various levels
Thank you