Spinal Cord for FBS

8/12/2019 Spinal Cord for FBS

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The spinal cord begin as a

continuation

of the medulla oblongata.

In adults, 42-45cm in long

Extend from the foramen magnum

in theoccipital bone to the level of the

L1 or L2(in adult)

In newborn infants, it extends to

the third or fourth lumbar vertebra

Elongation of the spinal cord stops

around age 4 or 5, but growthof the vertebral column continues


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Enlarged in two regions :

1. Cervical enlargment

(C4-T1 segment ofthe spinal cord)

2. Lumbosacral enlargment

(T11-S1 segment of

the spinal cord)

The spinal cord occupies

only the superiortwo thirds of the

vertebral canal


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The conus medullaris is tapering inferior end,

terminate as high as T12 vertebrae or

as low as L3 vertebrae

Cauda equina is bundle ofspinal nerve roots

arising from the lumbosacral enlargment & the

medullary cone, caudal to the termination

of the spinal cord resembles a horses tail

filum terminale:

-arising from the tip of the conus medullaris,

descend among the spinal roots in the cauda equina

-an anchor for the inferior end of spinal cord

and the spinal meninges

Two parts of filum terminale :1. Pial part / internal terminal filum

2. Dural part/external terminal filum


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Vertebral

column

Vertebralligament

Meninges

CSF

Denticulateligament

Cushion of fat &

connective tissuelocated in epidural space

Denticulate ligament :

Triangular-shaped membranous extensions of

the pia mater

suspend the spinal cord in the middle of its duralsheath


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Consist of dura mater, arachnoidmater & pia mater

Spinal dura mater :

Composed mainly of tough

fibrous with some elastic tissue, is

the outermost covering

membrane of the spinal cord

The spinal dura forms the spinal

dural sac, a long tubular sheath

within the vertebral canal.

The sac is anchored inferiorly to

the coccyx by the filum terminale

The spinal dura mater isseparated from the periosteum-

covered bone and the ligaments

that form the walls of the vertebral

canal by the epidural space.

Content of epidural space :

Fat, internal vertebral venous

plexuses, root of spinal nerves


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Spinal arachnoid mater :

is a delicate, avascular membrane composed of fibrous and elastic tissue

Their apposition is the dura-arachnoid interface , often erroneously referred toas the subdural space.

The spinal arachnoid is separated from the pia mater on the surface of the

spinal cord by the subarachnoid space.

Content of subarachnoid space :CSF; radicular, segmental, medullary, andspinal arteries; veins; arachnoid trabeculae.

The enlargement of the subarachnoid space in the dural sac, caudal to the

conus medullaris and containing CSF and the cauda equina, is the lumbar

cistern. It extends from the L2 vertebra to the second segment of the sacrum.


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L2-S2


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Spinal pia mater :

the innermost covering membrane of the spinal cord, is thin and transparent,

and closely follows all the surface features of the spinal cord

The spinal pia also directly covers the roots of the spinal nerves and the

spinal blood vessels. Inferior to the conus medullaris, the spinal pia continues

as the filum terminale


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The spinal cord is suspended in the dural sac by the

filum terminale and the right and left denticulate

ligaments

Denticulate ligament (sawtooth) :

Triangular-shaped membranous extensions of the pia

mater

suspend the spinal cord in the middle of its dural sheath

The 20-22 sawtooth-like processes attach to the inner

surface of the arachnoid-lined dural sac.


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The arteries derive from :

1.Vertebral artery

2. Ascending cervical artery

3. Deep cervical artery

4. Intercostal artery5. Lumbar artery

6. Lateral sacral artery

7. Three longitudinal artery :

An anterior spinal artery

Two posterior spinal artery


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8. Anterior segmental artery

9. Posterior segmental artery

10. The great anterior segmental

medullary artery (ofAdamkiewicz)

Contribute to the longitudinal

artery

The great anterior segmental

medullary artery (ofAdamkiewicz) is the largest

segmental medullary artery

supply cervical & lumbosacral

enlargment


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11. Radicular artery

At levels where there are no

segmental medullary artery,radicular artery supplies the

posterior & anterior roots of

the spinal nerves

Radicular artery are shown

at only the cervical &thoracic level, but they also

occur at the lumbar & sacral

levels


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12. Sulcal artery

Arise from the anterior spinal

artery & enter the spinal cordthrough anterior median

fissure

Supplies approximately two

thirds of the cross sectional

area of the spinal cord


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1. three anterior spinal veins

2. three posterior spinal veins

Drain up to :

1. 12 anterior medullary veins

2. 12 posterior medullary veins

3. radicular veins


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The gray matter on each side of the spinal cord is subdivided into regions called

horns.

The gray matter consist of :

The posterior (dorsal) gray horns

The anterior (ventral) gray horns

The lateral gray horns


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contain cell bodies and axons of interneurons as well as axonsof incoming sensory neurons.

The posterior(dorsal) gray

horns

contain somatic motor nuclei, which are clusters of cell bodiesof somatic motor neurons that provide nerve impulses forcontraction of skeletal muscles

The anterior(ventral) gray

horns

present only in thoracic and upper lumbar segments of thespinal cord.

contain autonomic motor nuclei, which are clusters of cellbodies of autonomic motor neurons that regulate the activityof cardiac muscle, smooth muscle, and glands.

The lateralgray horns


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The white matter on each side of the spinal cord is subdivided into regions called

columns/ funiculus

The white matter consist of :

The posterior (dorsal) white columns /funiculus

The anterior (ventral) white columns/funiculus The lateral white columns/funiculus


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Each column in turn contains distinct bundles of axons

having a common origin or destination and carrying similar

information.

These bundles, which may extend long distances up or

down the spinal cord, are called tracts.

Recall that tracts are bundles of axons in the CNS,whereas nerves are bundles of axons in the PNS


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In transverse sections of the spinal cord, the anterior and posterior gray

columns on each side are connected by a transverse gray commissure; the

gray matter resembles the letter H


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In the center of the gray commissure is situated the central canal.

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Spinal Cord for FBS