Transcript Slide 1

SPINAL CORD ANATOMY
General Characteristics
Approx. ½ meter in length.
 Varies from 1 to 1.5 cm in diameter.
 Enlargements:

Cervical:
C3 – T1.
Lumbar region:
L1 – S2.
General Characteristics

Conus medullaris:
Ends at about the level of L2.
Cauda equina.
 Filum terminale:

Thin filament of meningeal tissue extending
from conus medullaris to the coccyx.
Spinal Nerves
08 cervical.
 12 thoracic.
 05 lumbar.
 05 sacral.
 01 coccygeal.

Plexuses

Cervical:
C1 – C4.

Brachial:
C5 – T1.

Lumbosacral:
L1 – S4.
Cross-Sectional Anatomy
Central canal.
 Gray matter:

“H”-shaped.

White matter.
Gray Matter




Horns are equivalent to CNS nuclei.
Posterior (dorsal) horns:
Receive incoming sensory fibers.
Anterior (ventral) horns:
Site of cell bodies of alpha motor neurons to
skeletal muscle fibers.
Lateral horns:
Located only in thoracic and upper lumbar
region:
Site of cell bodies of ANS motor neurons.
White Matter
Columns are referred to as funiculi.
 Columns consist of myelinated tracts.
 Posterior (dorsal) columns.
 Anterior (ventral) columns.
 Lateral columns.

Commissures

White:
Anterior and posterior.

Gray:
Anterior and posterior.
Spinal Nerves
Dorsal rootlets.
 Dorsal root:

Carries afferent fibers.
With dorsal root ganglion:
Location of cell bodies of afferent neurons.

Ventral root:
Carries efferent fibers.
No associated ganglion.
Spinal Nerves

Spinal nerve carries a mixture of fibers:
Both afferent and efferent.
Both visceral and somatic.
Proprioceptive.
Primary Rami

Dorsal (posterior):
To expaxial musculature (deep back
muscles) and skin on either side of dorsum
of back.

Ventral (anterior):
To hypaxial musculature (rest of skeletal
musculature including muscles of limbs) and
rest of skin.
Autonomic Rami

White ramus communicans:
Carries pre-ganglionic sympathetic fibers
from lateral horns of central gray of spinal
cord (thoracolumbar regions).

Gray ramus communicans:
Carries post-ganglionic sympathetic fibers
from paravertebral ganglia back to spinal
nerve.
Meniniges
Epidural space.
 Dura mater:

Tough outer layer.
Subdural space.
 Arachnoid.

Meniniges

Subarachnoid space:
Contains CSF.

Pia mater:
Delicate innermost layer.

Denticulate ligaments.