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Spinal Cord I
Dr Ayman Abu-Tabanja
Vertebral Column
33 Vertebrae (segments):
7 Cervical
12 Thoracic
5 Lumbar
5 Sacral
4 Coccygeal
Spinal (vertebral) canal
Intervertebral foramen
COVERINGS OF THE SC
• Dura mater
Tube-like
Continuous with cranial dura
Extend to S2
Innervation
COVERINGS OF THE SC
• Arachnoid mater
Oppose the inner side
of dura
Outer boundary of
subarachnoid space
Termination
Lumbar cistern
COVERINGS OF THE SC
• Pia mater
Delicate
Tightly adherent to spinal
cord
Vascular
• Epidural space:
Filled with fat
Venous plexus
Spinal nerve roots cuadal
to S2
• Subarachnoid space:
CSF-filled
• Denticulate ligament:
Pia-arachnoid tissue
Serrated Appearance
Suspend spinal cord in
middle of spinal canal
Spinal cord consist of 31
segments
Vertebral column grows
faster than spinal cord
SPINAL VERSUS
VERTEBRAL SEGMENTS
C1 nerve (suboccipital
nerve)
C2-C7 nerve
C8 nerve
ALL T & L nerves
All S nerves
Co nerve
Gross morphology
Cylindrical
Flattened dorsoventrally
Has two enlargements
1. Cervical enlargement:
C4-T1
2. Lumbar enlargement:
L2-S3
• Anterior median fissure
• Posterior median sulcus
•Motor rootlets
•Sensory rootlets
• Conus medullaris
• Cauda equina
•Filum terminale:
Internum & externum
Adhere to dorsum of
coccyx
Lumbar Puncture
Lateral Recumbent Position
Structure of Spinal Cord
The Gray mater
H- shaped
Anterior & posterior gray horns
Gray commissure
Lateral gray horns
Anterior Gray Columns
Contain:
1. Alpha motor neurons
Larger multipolar
2. Gamma motor neurons
Smaller multipolar
Neurons arranged in three
groups:
1.Medial group
2.Central group
3.Lateral group
Anterior Gray Columns
1. Medial group
Present in all segments
Supply neck, trunck, intercostal
and abdominal muscles
2. Lateral group
Present in enlargements
Supply upper and lower limbs
Anterior Gray Columns
2. Central group:
smallest
A. Phrenic nucleus: C3-5
B. Accessory nucleus: C1-C5/6
C. Onuf’s nucleus: Sacral segments
Posterior gray columns
Three main nerve cell
groups:
1. Substantia gelatinosa
group:
Most posterior
All segments
Somatic sensations
Glogi II neurons
Posterior gray columns
2. Nucleus proprius:
Largest group
All segments
Large neurons
proprioception,
two point descrimination,
and vibration
Posterior gray columns
3. Nucleus dorsalis (clarke’s
group):
Most anterior
Large neurons
present from C8-L4
Associated with Proprioceptive
endings (muscle and tendon
spindles)
Posterior gray columns
4. Visceral afferent nucleus
Lateral to nucleus dorsalis
Medium neurons
present from T1-L3
Receives visceral sensations
Lateral Gray Horn
Present in T1 to L3
Contain intermediolateral
cell group
Give rise to preganglionic
sympatheic fibers
***There is
intermediolateral group
in S2-S4
The gray commissure
• Connects anterior and posterior horns on each side
• The central canal is located in it’s center
Divided into:
Anterior gray commissure
Posterior gray commissure
The central canal present throughout the spinal cord
Lined with ependyma
Filled with CSF
Closed inferiorly ( terminal ventricle)
White matter
Divided into:
1. Anterior funiculi
2. Lateral funiculi
3. Posterior funiculi
Gracile fasciculus
Cuneate fasciculus
White matter