Spinal cord in General . Arterial supply and
venous drainage of spinal cord
DR DUR E SHAHWAR
DEPT OF ANATOMY
SMC, JSMU
15/11/2014
Learning objectives
At the end of lecture students should be able to
•
Comprehend the normal gross anatomy of spinal cord.
•
Study the distribution of gray & white matter of spinal cord.
•
Discuss the blood supply of spinal cord.
•
Give the area of distribution of each artery and venous drainage.
•
Clinical applications.
Spinal cord
 Spinal cord is the part of central nervous system extented from the foramen megnum where
the 1st spinal nerves comes out to the lower border of L1.
 Spinal cord is cylinder.
 Lower end of spinal cord is cone like called conus medullaris.
 Vertically sp.cord possesses a deep midline groove, the anterior median fissure& shallow
posterior median sulcus.
 Spinal cord possesses two symetrical enlargements which occupy the segments of limb
plexuses: cervical enlargment—brachial plexuses & lumbosacral enlargment –lumber & sacral
plexuses.
 Both the enlargment are due to the greatly increased mass of motor cell in the anterior horn
of gray matter.
 Spinal cord is completely surrouned by the covering of meninges.
 The cavity of spinal cord is –central canal.
Internal structure of spinal cord
 Spinal cord consist of central mass of gray matter ( cell bodies) enclosed by column of white
matter ( nerve fibers).
 It is divided into two halves by the anterior median fissure & posterior median septum.
 Gray commissure connects the gray matter of right & left halves of cord.(H—shape in cross
section).
 It contain centrally central canal.
Anterior & posterior septum & fissure does not divide the two halves completely & connected with
each other by anterior & posterior white commissures.
Both the gray & white matter of right & left halves are divided into anterior, posterior & lateral
columns of cells & fibers.
Gray matter
 Central gray column is roughly H—shaped structure consist of cell bodies.
 It divided into anterior horn cell, posterior horn cell& lateral column cell in thoracolumber
region.
 Anterior horn cells are motor nuclei.
 Posterior horn cell are sensory in function.
 Lateral horn cell are sympathetic cell bodies.
White matter
White matter of spinal cord contain three columns.
Division is done by the anterior & posterior nerve roots.
They are anterior white column, posterior white column& lateral white column.
Posterior white column lies b/w the posterior median septum & posterior nerve root of spinal nerve.
Anterior white column lies b/w the anterior median fissure & anterior root of the spinal nerve.
Lateral white column lies b/w the anterior & posterior nerve root of spinal nerve.
Spinal nerve
 Anterior & posterior roots of spinal nerve with in the intervertebral foramen to form spinal
nerve.
 Anterior nerve root is motor nerve root supply the muscles & gland.
 Posterior root is sensory carry all the peripheral information to the brain.
 Posterior root ganglia on the posterior nerve root lies in the intervertebral foramen.
Afferent pathway
All the periphral information from the sensory receptor in the musclec skin & joint posterior root to
the posterior gray horn (nuclei) specific white column thalamus sensory cortex of cerebrum.
Pathway consist of 1st order neuron 2nd order neuron  3rd order neuron.
Efferent pathway
To control the skeletal muscles activity antereior nerve root  spinal nerve.
All the information from the opposite motor cortex of brain passes to the main tract to the anterior
gray horn nuclei  passes through the anterior nerve root to the spinal nerve of specific site.
Motor pathway consist of 1st order neuron 2nd order neuron  muscle .
BLOOD SUPPLY SPINAL CORD
Metabolically CNS (brain + spinal cord) is one of the most active systems of body.
Metabolism depends almost on the aerobic combination of glucose
.
Because if there is decrease storage of glucose or oxygen in the brain, even brief interference with
cerebral circulation can cause permanent neurological or mental ditrurbance
.
Neural tissue deprived by the blood supply goes under necrosis.
Impairment of regional or local blood supply constitutes the most common cause of CNS lesions.
Estimate of cerebral out flow is about 50ml/100gm/min of brain tissue. Thus the average blood flow to
the average weight brain is about 750ml/min.
The brain requires 17% of normal cardiac output and 20% of oxygen utilized by the entire body.
If the adequate circulation is not maintained to the local regions of brain and spinal cord, neural tissue
undergoes softening, necrosis and degeneration.
Vascular lesions
Brain infarcts
Aneurysms
Emboli
Spontaneous haemorrhage
Blood supply of spinal cord:
Arteries:
The spinal cord is supplied by the branches of (1) vertebral arteries (1st part of S/C artery).
(2)
Multiple redicular arteries derived from segmental vessels (spinal branches of vertebral artery, deep
cervical, post intercostal and lumbar artery).
Vertebral arteries: On the antero lateral surface of medulla the vertebral arteries give rise to two paired
descending vessels anterior spinal artery (Ant. Median fissure) and Posterior spinal artery.
Anterior Spinal artery:
The two anterior spinal arteries on each side seen join in the median plane to form a single descending
midline vessel in front of medulla oblongata and give the sulcal branches to enter in anterior median
fissure of spinal cord.
Redicular branches from deep cervical posterior intercostal and lumbar region again join the anterior
spinal artery hence forming a plexus with in the piamater with other branches.
Area of supply:
Anterior and lateral gray column.
Base of post gray column.
Anterior fasciculus
Part of lateral fasciculus
Posterior spinal artery:
These paired posterior spinal arteries descend on the posterior surface of the spinal cord receiving
contributions from the posterior reduclar arteries and form two plexiform channels near the dorsal root
entry zone.
Area of supply:
Posterior gray horn (except base).
Posterior luniculus.
Part of lateral lunuculus.
Redicular arteries:
They are derived from segmental vessels i.e. (ascending and deep cervical, intercostal, lumbar and sacral
artery).
They pass through I/v foramina divide into anterior and posterior redicular branches and provide
principal blood supply to thoracic, lumbar, sacral and coccygeal spinal segments.