Download Objectives Vertebral Column

Anatomy of the Spinal
Cord and Vertebral
Column and How it
Relates to Spine Surgery
Dori Danbury MSPAMSPA-C
Department of Neurosurgery
University of Michigan
MANS Conference
June 12, 2010
Objectives
Understand the anatomy of the vertebral
column
Understand the basic anatomy of the spinal
cord parenchyma and its connections
Apply the basic anatomy of the vertebral
column and spinal cord toward
understanding clinical disorders of the spine
and surgical procedures
Vertebral Column
Provides protection to the delicate
spinal cord/nerves
Provides support so we can be upright
There are 5 segments to
the vertebral column
Curvature of the spine
The over all shape of the spine allows
for us to be upright.
2 areas of lordosis
2 areas of kyphosis
– Cervical and Lumbar
– Thoracic and Sacral/Coccyx
Lordosis
Kyphosis
Lordosis
Kyphosis
Important structures to
know of the spine
Vertebral Body
Lamina
Spinous Process
Pedicle/Lateral Mass
Disc
Facet joints
Foramen (Neuroforamen)
Axial
Vertebral
body
Sagittal
Pedicle
Vertebral
body
Lamina
Spinous Process
Vertebral Disc
Purpose
– Provide cushioning between the bones to help with axial
loading
– Discs are usually only present from C2C2-3 to L5L5-S1
Annulus Fibrosus
Nucleus Pulposus
– A thick fibrous ring that is the outer edge of the cushion
– The softer inside material of the disc that provides the
cushioning
– Has the consistency of crab meat
Annulus Fibrosis
Axial
Nucleus pulposus
Sagittal
Superior Facet Joint
Inferior Facet Joint
Neuroforamen
Notice that the nerve root exits at the top of the foramen
Notice that the disc is below the nerve root
Ligaments
Anterior Longitudinal Ligament
– Connects the vertebral bodies together
anteriorly
Posterior Longitudinal Ligament
– Connects the vertebral bodies together
posteriorly
Ligamentum Flavum (Yellow Ligament)
– Connects the lamina together posteriorly
Cervical Spine
7 vertebral bodies
Specialized structure of C1 and C2
– Smaller bones/structures
– Allows for movement of the head in
forward and backward directions, and
side to side motions.
C1
Also called the Atlas
– A bony ring that supports the Occiput and
allows for flexion and extension of the
head
– Works with C2 to allow movement of the
head from side to side
Area of articulation with C2 (dens)
Lateral mass
Transverse
foramen
lamina
Transverse foramen
Articulation of C2 (dens)
Lateral mass
lamina
Spinous process
C1 ring
C2
Also called the Axis
Has a specialized protrusion called the
Dens
– Allows the ring of C1 to rotate
Dens
Lateral mass
Vertebral Body
Transverse foramen
Lamina
Spinous
process
C2
Vertebral
Body
Transverse
foramen
Lateral Mass
Lamina
Spinous Process
Special circumstances
Placement of screws
Vertebral arteries
– Lateral Mass not Pedicle
Thoracic Spine
12 vertebral bodies
Attached to the ribs
The foraminal opening is larger in the
thoracic area than the cervical
Cerebral
Spinal Fluid
Spinal
Cord
Vertebral
Bodies
Discs
Conus
Medullaris
Lumbar Spine
5 vertebral bodies
Larger as they descend from L1 to L5
Conus
Medullaris
Cauda
Equina nerve
roots
Picture
Picture
Sacrum/Coccyx
Sacrum
5 segmentssegments-usually fused
– no discs between segments (usually)
– Sits in the pelvic bone (ilium)
Coccyx
3-5 segments
Spinal Cord Anatomy
The spinal cord’
cord’s purpose is to transmit and
receive information between the brain and
the rest of the body.
It begins at the craniocervical junction and
ends usually between T12 and L2.
The end of the spinal cord is called the
conus medullaris (conus).
From the conus spinal nerves go to the
lower extremities, and bowel/bladder. This
area is called the Cauda Equina
The cord is composed of
descending and ascending
tracts
Ascending tracts transmit sensory
information from the body back to the
brain
Descending tracts transmit motor
information from the brain to the body
Surrounding Coverings
Pia Mater – a thin connective tissue
that forms the outer layer of the spinal
cord
Arachnoid Membrane – a combination
of collagen and elastin fibers that
suspend the cord
Dura Mater – a connective tissue that
forms a tube that keeps the cerebral
spinal fluid in place
The spinal cord has a central portion
of gray matter surrounded by white
matter
The Gray Matter is divided
into sections
Ventral (anterior) Horns
– Sends information to the ventral root of the
spinal nerve. Controls somatic motor function
Dorsal (posterior) Horns
– Receives sensory information from the dorsal
root of the spinal nerves via the dorsal root
ganglion
Lateral Horns –Found from T1T1-L2 only
– Sends information through the ventral root of
the spinal nerve. Controls autonomic motor
function
Dorsal horns
Dorsal horn
Lateral horn
Ventral horn
Ventral horns
Lateral
horns
Note: The shape of the gray
matter varies within the cord
The gray matter has a modified H or
butterfly shape
– The more muscles that are innervated the
larger the gray matter
Cervical
Thoracic
Lumbar
The White Matter is divided
into columns
Anterior column
– from the anterior midline to the emergence of
the ventral nerve root
Lateral column
– from the ventral nerve root to the dorsal nerve
root
Posterior column
– from the posterior midline to the dorsal nerve
root
Posterior Column
Lateral Columns
Anterior Column
Anterior and Lateral
White Columns
Have numerous tracts that relay
information to the brain through
ascending tracts.
We will only cover a few of these
tracts
Anterior Spinothalamic
tract
Relays the sensation of crude touch
and pressure – not highly
discriminatory
Lateral Spinothalamic
Tract
Relays pain and temperature
sensations
Posterior White Column
Contains ascending tracts of axon fibers that
transmit sensory information (conscious
proprioception, fine touch and vibratory senses) to
the brain from the body
– Fasciculus gracilis – (medial portion of the
posterior column) contains fibers from the
sacral, lumbar, and lower 6 thoracic segments.
– Fasciculus cuneatus - (lateral portion of the
posterior column) contains fibers from T6
through cervical segments
Posterior Spinocerebellar Tract
Allows the brain to know where parts
of the body are located in space
– This is an unconscious process, as well as
a conscious process
Descending tracts
There are numerous tracts that are
involved with controlling muscle
Only a few will be discussed
Corticospinal tracts
Control discrete voluntary movement
of the muscles
Starts in the cerebral cortex, crosses
to the contralateral side within the
midline of the cord and ends in the
ventral horn.
– There the axons will form the ventral root
of the spinal nerve
Upper vs. Lower Motor
Neurons
Upper Motor Neurons start in the
cerebral cortex or brain stem and then
end in the spinal cord, above the
ventral horn (gray matter)
Lower Motor Neurons start in the
ventral horn and go to specific
muscles (spinal nerves)
Radiculopathy
Strength
may be decreased
Fine Motor
normal
Proprioreception
normal
Reflexes
decreased
Gait
normal or antalgic
Pain
radiating
Tone
normal
Signs
Straight leg raise
Spurling’s
vs
Myelopathy
may be decreased
decreased
may be decreased
increased
ataxic
none or hypersensitive
may be increased
Hoffman’s(cervical)
Clonus, Babinski
Blood supply of the Spinal
Cord
Approximately 75 % of the blood
supply to the spinal cord is through
the Anterior Spinal Artery
Approximately 25% is from the
Posterior Spinal Artery
Diseases that affect the different tracts of the spinal cord
A. Polio
B. Multiple Sclerosis
C. Syphilis
D. Lou Gehrig’s Disease
(ALS)
E. Brown-Sequard
F. Anterior spinal artery
occlusion.
G. vitamin B12
neuropathy
H. Syringomyelia
Spinal Nerves
Exit the spinal cord and leave the vertebral column to
go to various portions of the body
– Are formed by a ventral root (motor) and dorsal root
(sensory).
The ventral and dorsal root are made from nerve rootlets
that come from the horn of the gray matter
The dorsal root forms a dorsal root ganglion where the
cell bodies of each sensory nerve is found.
– The dorsal ganglion of each spinal nerve is found in
the neuroforamen, except C1 does not have one.
There are 31 spinal nerves on each side of the body
The nerve roots exit …
Cervical - the nerve roots are named
based on the vertebral body below the
foramen
– Except C8 which changes the naming.
This exits in the C7-T1 foramen.
Thoracic – Sacral – the nerve roots are
named for the vertebral body above
the foramen
You can localize nerve root
compression based on the
location of pain
_Disc/Stenosis__
C4C4-5
C5C5-6
Nerve
5
6
C6C6-7
7
C7C7-T1
8
_____Pain______
_____Pain______
deltoid
biceps, lateral
forearm, 11-3rd digits
triceps, middle
posterior forearm,
2-3rd digits
medial arm, 44-5th
digits
Disc/Stenosis
Nerve
L2L2-3
L3L3-4
L3
L4
L4L4-5
L5
L5L5-S1
S1
__ Pain_____
medial thigh/calf
anterior thigh,
medial tibia/ankle
lateral thigh,
dorsal foot, big toe
posterior thigh,
calf, lateral foot
Thank You
References
“Back Anatomy.” NoBackSurgeryInfo.com. 2008. Web. 08 May
2010.
de Assis Aquino Gondim, Francisco, M.D., “Spinal Cord,
Topographical and Functional Anatomy.”, emedicine.
medscape.com., 02 Apr 2009. Web. 18 Mar 2010.
“Radiculopathies.” University of WI. n.d. Web. 03 Apr. 2010.
Snell, Richard S., “Clinical Neuroanatomy”, 7th Ed.,
Philadelphia:Wolters, 2010. 132-180. Print.
“Spinal Cord Anatomy.” Apparelyzed.com. Apparelyzed Spinal
Cord Injury Support Group. n.d. Web. 14 Jan 2010.
“Upper and Lower Motor Neurons.” Wikipedia. Wikipedia
Foundation. 13 May 2010. Web. 14 May 2010.