Dr. Nishtha Jain

Senior Resident

Department of Neurology

GMC, Kota

Part of the central nervous system (CNS)

Extends caudally

Protected by the bony structures of the vertebral column.

Covered by the three membranes of the CNS, i.e., the

dura mater, arachnoid and the innermost pia mater.

Occupies only the upper 2/3 of the vertebral canal.

By age 2 months, it reaches the adult L1-L2 level.

The average length- 45 cm(adult male) and 42 to 43

cm(adult female).

The corresponding average length of the spinal column

is 70 cm.

If the level of the tip of the conus is below the mid-L2

vertebral body, the conus is considered low-lying.

According to its rostrocaudal location the spinal cord can

be divided into four parts:

-cervical,

-thoracic,

-lumbar and

-sacral.

The number of spinal

nerves and spinal

segments:

-8 cervical,

-12 thoracic,

-5 lumbar,

-5 sacral and

-one coccygeal spinal

segment

SPINAL CORD LEVELS RELATIVE TO

THE VERTEBRAL BODIESSPINAL CORD LEVEL CORRESPONDING

VERTEBRAL BODY

Upper cervical Same as cord level

Lower cervical +1

Upper thoracic +2

Lower thoracic + 2 to 3 levels

Lumbar T 10 – T 12

Sacral T 12 – L1

ENLARGEMENTS ENLARGEMENTS :

contains more motor neurons to supply the limbs

• Cervical: Extends from C5 to T1 segments to form brachial plexus

widest circumferance-38mm at C6

Lumbosacral: Extends from L2toS3 to form lumbosacralplexus.

Widest circumferance -35mm at S1

LAMINA

I Nucleus posteromarginalis

II Substantia gelatinosa

III and IV Nucleus proprius dorsalis

V Zone anterior to lamina IV

VI Zone at the base of dorsal horn

VII Intermediate zone

VIII Zone in the ventral horn (restricted to medial aspect

in cervical and lumbar enlargements)

IX Medial and lateral anterior horn cell columns.

X cells surrounding the central canal

PATHWAYS IN THE SPINAL CORDAscending (afferent) pathways Descending (efferent)

pathways

Descending tracts Five descending systems exert tonic effects on the motor

neurons.

The vestibulospinal tract and The medial reticulospinal

tract tend to facilitate the motor neurons of antigravity

muscles.

The corticospinal tract, The corticorubrospinal tract, and

The lateral reticulospinal tract inhibit the antigravity

muscles and facilitate the antagonists.

VESTIBULOSPINAL TRACT

RETICULOSPINAL TRACT

RUBROSPINAL TRACT TECTOSPINAL TRACT

LATERAL SPINOTHALAMIC TRACT

ANTERIOR SPINOTHALAMIC TRACT

SPINOCEREBELLAR TRACT

HEMISECTION OF SPINAL CORD

(BROWN-SEQUARD SYNDROME)

Central cord syndrome

Seen in syringomyelia

Interrupt fibres of lateral

spinothalamic tract that

passes in front of the

central canal.

sensory dissociation

Arterial Supply to the Spinal Cord

Anterior spinal artery:

ORIGIN: Branches of right and left vertebral arteries in

the upper cervical canal.

COURSE: runs caudally in the anterior median fissure.

TERMINATION: filum terminale

SUPPLIES: Anterior two third of the cord

Two posterior spinal arteries:

ORIGIN : Branched from either 1. Vertebral 2.Posterior inferior cerebellar arteries.

COURSE: Runs down in the posterolateral sulcus divides into two collateral arteries medial and lateral along the posterior nerve roots.

These communicate around the cord forming pial plexus arterial vaso corona/arteriae coronae.

SUPPLIES :Posterior one third of the cord

Segmental arteries:

Branches of Deep cervical, Ascending cervical, Intercostal and Lumbar

Segmental arterial feeders reach the cord as anterior and posterior radicular arteries.

ANTERIOR RADICULAR ARTERIES: Larger and less in number.

POSTERIOR RADICULAR ARTERIES: Smaller and more in number.

Great anterior medullary artery of Adamkiewicz-arises from aorta at T12 or L1 vertebral level unilateral left side

Anterior Spinal Artery Syndrome

-Back or neck pain of sudden onset

-Rapidly progressive flaccid and areflexic paraplegia

-Loss of pain and temperature to a sensory level

-Preservation of proprioception and vibration sensation

-Urinary incontinence

Posterior spinal artery syndrome

-Loss of proprioception and vibratory sense

-Preserved pain and temperature sensation

-Loss of myotatic and cutaneous reflexes below involved

segment

-Absence of motor deficits

VENOUS DRAINAGE

Two median longitudinal

Two anterolaterlal

Two posterolateral

Drain below through internal vertebral venous plexus into

the vertebral posterior intercostal, lumbar, and lateral

sacral veins.

And drain above into the basilar venous plexus.

THANK YOU

Referrences Localization in clinical neurology by Paul W. Brazis 6th

edition

Bradley’s Neurolgy in clinical practice 6th edition

DeJong's The Neurologic Examination, 6th Edition

Textbook of Human Neuroanatomy by Inderbir Singh 9th

edition

Anatomy and Physiology of the Spinal Cord. Madame

Curie Bioscience Database