The spinal cord is approximately 45-50 cm long and 2 cm in diameter. It begins at the foramen magnum and terminates around the L1-L2 vertebrae in adults. The spinal cord has ascending tracts that carry sensory information to the brain and descending tracts that carry motor commands from the brain. It is protected by the vertebrae, meninges, cerebrospinal fluid, and contains gray matter in an H-shaped arrangement surrounded by white matter tracts. Injuries and diseases of the spinal cord can result in sensory and motor deficits depending on the level and severity of the lesion.

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Spinal cord
by Dr Vyom Jain

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Dimension : approx. 45-50 cm long
2cm in diameter
Begins From : Outside skull, from
foramen magnum
Terminates at : "Conus Medullaris"
Fetal 3rd
month: Ends at coccyx
Birth: Ends at L3
Adult: Ends at approx L1-2
Cauda Equina : B/w L2-S2 , also called as
"Horse Tail".
Denticulate ligaments: Lateral shelves of
pia mater anchoring to dura.
Filum Terminale : "Terminal Thread".
About 20 cm in length &proceeding
downwards from conus medularis.

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Functions :
A. Sensory Functions : Sensations after entering the
spinal cord in dorsal nerve root are conveyed to the brain
by ascending either in the:
i. Dorsal column of the same side (Fine touch,
tacile localization & discrimination, pressure,
proprioception& kinesthetic sensation)
ii. Spinothalamic tracts of the opposite side
(Anterior conveys gross touch & tactile localization
whereas Lateral conveys pain & temperature)

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B. Motor Function :
1. The tone & power of the muscle
2. The movements of the muscle & joint
3. The deep tendon reflexes
4. The superficial reflexes
these functions are conveyed by Pyramidal &
Extrapyramidal tracts.
C. Autonomic Functions :
1. The Body temperature &
2. The visceral functions i.e., regulates the activity
of smooth muscles, heart, glands of GIT,sweat gland,
adrenal etc.
•Main aim is to maintain the optimal internal environment
of the body.

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ANATOMY

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CROSS SECTION OF SPINAL CORD
A cross section will show :
1. Anterior median fissure (Prominent), Posterior median fissure (Less
prominent), and a central canal (B/w these fissure)
2. Grey matter consist of nerve cells formin an H-shaped figure in
which
a. Dorsal (Posterior) Horn : Long and narrow
b. Ventral (Anterior) Horn : Broad
c. Grey Commissure : surrounds central canal antero-
posteriorly.

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3. Anterior horn : Contains cell body of α,γ & Renshaw motor
neurons; these fibers ae purely motor in function.
Posterior horn : Recieves the fibers of the posterior roots which are
purely sensory in function.
Lateral horn : Contains cell bodies of autonomic neurons
(Sympathetic), extends only b/w T1&L2
4. White matter surrounds grey matter contains large number of
ascending and descending tracts and has 3 columns :
a. Anterior white column
b. Lateral white column
c. Dorsal white column
5. The sensory and motor fibers join to form the mixed nerves which
comes out from vertebral canal as peripheral spinal nerve via
intervertebral foramen.

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Enlargement of spinal cord:
1. Cervical enlargement : Upper limb through
brachial plexus.
2. Lumbar enlargement : Lower limb through
lumbosacral plexus.
Functional and structural organizations:
A. i. execution of the simple reflexes
ii. transmission of impulse to & fro the brain.
B. Sensory information :
i. information at conscious level to the thalamus and
cerebrum for interpretation
ii. information at unconscious level to cerebellum for
coordinating the muscular activity and to tectum of midbain for
visual reflexes.
C. Different types of sensations perceived are :
i. Protopathic (pain, touch & temperature)
ii. tactile localization, tactile discrimination &
proprioception.

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Nuclei Of Spinal Cord :
Anterior grey column :
i. Medial group : Present through entire length of spinal
cord. (Dorsomedial, Ventromedial)
ii. Lateral group : Present in cervical & lumbar enlargement.
(Anterolateral, posterolateral, post-posterolateral)
iii. Central group : only in upper cervical segments (Phrenic
& accessory nerve)
Lateral grey column :
i. Intermediolateral nucleus : acts as both efferrent and
afferent columns (T1-L2 Sympathetic & S2-S4 Parasympathetic)
ii. Intermediomedial nucleus : Internuncial neuronal column.
Posterior grey column :
i. Posterior marginal nucleus : thin layer o neurons caps the
posterior horn & recieve some of the dorsal root fibers.
ii. Substantia gelatinosa : run through spinal cord at the
posterior tip. acts as relay station for pain and temperature fibers.
iii. Nucleus proprius : It lies adjacent to substantia
gelatinosa. concerned with sensory associative mechanism.
iv. Nucleus dorsalis : "Thoracic nucleus" from C8-L3
segments. (relay for reflex and unconscious proprioception)

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Laminar organization Of Spinal Cord :
10 layers of neurons are recognized known also as laminae of Rexed.
These are numbered consecutively by Roman numerals, starting from
the tip of dorsal horn till the ventral horn.
Lamina I : Corresponds to posteromarginal nucleus.
Lamina II : To the substantia gelatinosa
Laminae III & IV : To nucleus proprius.
Laminae V & VI : Correspond to base of dorsal column.
Lamina VII : Territory b/w dorsal & ventral horns.
Lamina VIII : corresponds to ventral horn in thoracic segments.
Lamina IX : Includes the lateral group of nuclei of the ventral horn.
Lamina X : Surrounds the central canal.

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Tracts Of Spinal Cord :
Tracts are defined as the collection of nerve fibers which have same
origin, course & termination.
Classification:
1. Descending(motor) tract :
a. Pyramidal or corticospinal : Anterior corticospinal &
Lateral corticospinal
b. Extrapyramidal :
i. Rubrospinal
ii. Reticulospinal
iii. Tectospinal
iv. Vestibulospinal
v. Olivospinal
2. Ascending(sensory) tract :
a. For protopathic sensations:
i. Lateral Spinothalamic tract : Pain & Temperature
ii. Anterior Spinothalamic tract : Touch & Pressure
b. For proprioceptive sensations :
i. Fasciculus Gracilis
ii. Fasciculus Cuneatus
c. For reflex proprioception :
i. Dorsal & Ventral Spinocerebellar tracts

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Spinal
Nerves:
Part of the peripheral nervous system :
• 31 pairs attach through dorsal and ventral nerve
roots
• Lie in intervertebral foramina
• Divided based on vertebral locations
(8 Cervical,12 Thoracic, 5 Lumbar, 5 Sacral, 1
Coccygeal)
• Cauda equina (“horse’s tail”): cCllection of nerve
roots at inferior end of vertebral canal.

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• Cervical spinal nerves exit from above
the respective vertebra
(Spinal nerve root 1 from above C1
Spinal nerve root 2 from between C1 and C2,
etc.)
• Clinically, for example when referring
to disc impingement, both levels of
vertebra mentioned, e.g. C6-7 disc
impinging on root 7

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PROTECTION :
• Spinal Cord is being protected by Bone,Meninges &
CSF.• Meninges are of 3 type from outside to inside :
• Dura Mater
• Arachnoid Mater
• Pia Mater
• 3 Potential spaces are :
• Epidural : Outside the Dura Mater
• Sub-Dural : Between Dura & Arachnoid Mater
• Sub-Arachnoid : Deep to Arachnoid Mater.

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Clinical Anatomy:
1. Poliomyelitis : It is a viral disorder in which dorsal horn cells
involved & cells leading to flaccid paralysis. It is LMN paralysis.
2. Syringomyelia : It is the conditionin which there is dialation
of central canal of spinal cord usually in cervical region. leads to
bilateral loss of pain & temperature
3. Subacute combined degeneration : There is bilateral
demyelination & loss of nerve fibers in the posterior &
posterolateral white columns of spinal cord. (Vit. B12
deficiency). Gait is ataxic
4. Amyotropic lateral sclerosis : Bilateral degenerative disease.
degenerstion id restricted to the motor system affecting
corticospinal tract & anterior horn cells. Therefore the signs are
combination of upper & lower motor neuron effect.

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Transection of the spinal cord :
A. Complete transection :
Causes : Gunshot injury, dislocation of the spine, occlusion
of the blood vessels. It results in :
• Loss of all sensibility & voluntary movement below the lesion.
• Patient is Quadriplegic (upper cervical segment is transected),
Paraplegic (transection b/w cervical & lumbosacral)
• Bilateral LMN paralysis in segment of lesion
• Bilateral UMN paralysis below level of injury
• function of urinary bladder & bowel is disturbed.
B. Partial transection or hemi-section : (Brown-Sequard syndrome)
Motor and sensory loss at the level of injury.

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Lumbar Puncture :
• Also called as Spinal
Tap.
• In this a needle is
introduced into
subdural space to
collect CSF
• Lumbar Spine is
needed to be flexed so
can go between
spinous processes.
Epidural space is external to dura:
Anesthestics are often injected into epidural
space
Injection into correct space is vital; mistakes can