NEUROANATOMY SPINAL CORD DIVISION GROSS FEATURES BLOOD SUPPLY MENINGES

1. SPINAL CORD 1.
DR.DEEPAK N KHEDEKAR
DEPT.OF ANATOMY
LTMMC &GH
2015

2. Objectives
• External features
• Spinal segments
• Correlation with spinal segment and vertebral
segment
• Dermatomes & Spinal segments & related supply
• Gray mater & white mater
• Meninges
• Lumbar Puncture
• Blood supply.

3. INTRODUCTION
• Elongated part of CNS.
• Cylindrical in shape. (30gm)
• Present in upper 2/3 rd of Vertebral canal.
• 45 cm in male 42 cm in female.
• Begins superiorly at the foramen magnum
• Continuous with the medulla oblongata

4. INTRODUCTION
• In adults, terminates inferiorly @ the level of
the lower border of the first lumbar vertebra
(L1)
• In young child, it is relatively longer and
usually ends at the upper border of the third
lumbar vertebra.(L3)
• Level is however variable cord may terminate
one level above or below.

5. INTRODUCTION
• Occupies the upper two-thirds of the vertebral canal
of the vertebral column
• Coverings:
Surrounded by 3 meninges-
 Dura mater,
 Arachnoid mater
 Pia mater.
• Protection is also provided by the Cerebrospinal
fluid, which surrounds the spinal cord in the
subarachnoid space.

6. SPINAL MENINGES
• Three protective membranes
• From outside inwards(DAP) these are:
Dura mater,
Arachnoid mater,
Pia mater

7. Dura mater
• Extends- from foramen magnum to the lower
border of second sacral vertebra (S2).
Epidural space
Present between spinal dura and vertebral canal.
Contains loose areolar tissue, semiliquid fat and
internal vertebral venous plexus.
Subdural space
Space between dura and arachnoid mater .
Contain capillary layer of fluid.
Spinal dura differs from cranial dura.

9. Arachnoid Mater
• Thin, delicate, transparent, avascular membrane
• Invests the spinal cord loosely.
• Above it is continuous with the Arachnoid mater of the
brain and below it extends up to the lower border of
the S2
Subarachnoid space
• Betwn Pia mater and Arachnoid mater ,filled with CSF.
• Distal to the termination of spinal cord, the sub-
arachnoid space around the filum terminale, becomes
roomy, forming a pool of CSF called lumbar cistern.(Site
for lumbar puncture).

10. LUMBAR
PUNCTURE

11. Pia mater
• Thin, highly vascular membrane that closely invests.
• Continues below the spinal cord as a thin thread-like
prolongation, the filum terminale.
• Above it is continuous with subarachnoid space
around the brain.
Filum Terminale:
• 20 cm long
• Consist of 2 part
 Filum Terminale internum
 Filum Terminale externum

12. Spinal cord
External features

13. Spinal cord Enlargements
Spinal cord is fusiformly enlarged.
Cervical (C4-T2)
Lumbar enlargements (L2-S3)
• Cervical region -brachial plx.
• lower thoracic & lumbar regions- Lumbosacral plx
• Inferiorly, the spinal cord tapers off into the conus
medullaris, from the apex of which a prolongation
of the pia mater, the filum terminale, descends to
be attached to the posterior surface of the coccyx.

14. Spinal
enlargement

16. Spinal cord –fissures and Sulci
• Anterior median fissure -a deep longitudinal
fissure called the in the midline anteriorly.
• Posterior median sulcus- shallow furrow
called the on the posterior surface.
Spinal Nerves
• Along the entire length of the spinal cord are
attached 31 pairs of spinal nerves by the
anterior or motor roots and the posterior or
sensory roots .

17. Spinal nerve root
• Each root is attached to the cord by a series of
rootlets, which extend the whole length of the
corresponding segment of the cord.
• Each posterior nerve root possesses a
posterior root ganglion, the cells of which give
rise to peripheral and central nerve fibers.

19. Spinal segments
• Spinal cord is also segmented though the segments are
not visible externally.
• The part of spinal cord to which a pair of spinal nerves
(right and left) is attached is known as spinal segment.
• The number of spinal segments corresponds to the
number of vertebrae in thoracic,lumbar and sacral
regions,
• But in cervical region, one segment is more than the
number of vertebrae, whereas in coccygeal region
there is only one segment for four coccygeal vertebrae.

20. Spinal segment

21. Spinal
segments

22. Spinal segments
31 spinal segments:
8 cervical,
12 thoracic,
5 lumbar,
5 sacral
one coccygeal.

23. Spinal segments
Length of spinal cord (45 cm)
Length of vertebral column (65 cm),
Spinal segments are, short and crowded,
especially in the lower part of the cord.
Spinal and vertebral segments do not lie at the
same level.
Spinal segments lie above their numerically
corresponding vertebral spines.
In the lower part ,lie well above their
corresponding vertebrae e.g the lumbar segments
are related to the thoracic vertebrae.

24. Spinal
segment
vs
vertebral
segments

25. Spinal cord
Internal features

26. Spinal cord C/S

27. C/S SPINAL CORD
Shows…
Inner core of gray matter seen as an H-
shaped pillar
Outer covering of white matter
Pattern of grey/white matter is reversed in the
cord
There is no indication that the cord is
segmented

28. Grey mater
Consists of –
• Mixture of nerve cells and their processes,
neuroglia, blood vessels.
• Nerve cells are multipolar, and the neuroglia
forms an intricate network around the nerve
cell bodies and their neurite.
• Arranged in f/o Anterior and posterior gray
columns, or horns,
• United by a thin gray commissure around
containing the small central canal .

29. Gray Matter
• Small lateral gray column or horn is present in
the thoracic and upper lumbar segments of
the cord.
• Amount of gray matter present at is related to
the amount of muscle innervated at that level.
• Its size is greatest within the cervical and
lumbosacral enlargements of the cord, which
innervate the muscles of the upper and lower
limbs, respectively.

30. 5th cervical segment

31. 2nd Thaoracic region

32. Structure of the grey matter
Grey mater of spinal cord consists of
• Nerve cells,
• Neuroglia, and
• Blood vessels.

33. Neurons in the grey matter of the SpC
Structural classification:
• Golgi type I: having long axons, which leave
the grey matter and either join the anterior
nerve roots or form the nerve tracts.
• Golgi type II: having short axons, which do not
leave the grey matter and remain
intrasegmental or intersegmental in position.

34. Neurons in the grey matter of the SpC
Functional classification of motor neurons:
(in the anterior and lateral horns).
• Types of motor neurons in grey columns:
Alpha (α) neurons:
• Large multipolar cells (25 μm or more in diam.)
• Supply the extrafusal skeletal m.
Gamma (γ) neurons:
• Small multipolar cells (15–25 μm in diam.)
• Supply the intrafusal muscle fibres of the
neuromuscular spindles in skeletal m.

35. Neurons in the grey matter of the SpC
Sensory neurons:
• Present in the posterior horn
• Involved in relay of sensory information to
the different parts of the brain
• Forming ascending tracts; or to the other
segments of spinal cord forming interseg-
mental tracts.

36. Neurons in the grey matter of the SpC
Interneurons:
• Small neurons ,present throughout the grey
matter of the spinal cord.
• Connect different types of neurons, hence
also called Association neurons.
• Are either inhibitory or excitatory
• Concerned with integration of segmental
activities.

37. Nerve cell groups in the grey columns
of the SpC
Anterior
Posterior
Lateral

38. 1.Cell groups in the Anterior grey
column
• Divided into three main groups or nuclei:
 Medial
 Lateral
 Central.

39. 1.Cell groups in the Anterior grey
column

40. 1.A.Anterior grey column -Medial
group
• Extends along most of the length of the spinal
cord.
• Innervate the Axial musculature of the neck
and trunk.
• Subdivided into-
Ventro-medial
Dorso-medial

41. 1.B.Anterior grey column -Lateral
group
• Confines in the Cervical and Lumbo-sacral
Enlargements.
• Supply the limb muscles.

42. 1.C.Anterior grey column- Central
group
• Forms 3 definite nuclei:
 Phrenic nucleus, cervical region (C3 to C5)
innervating the diaphragm.
 Lumbosacral nucleus in the lumbosacral
region (L2 to S3).
 Spinal nucleus of accessory (XI cranial) nerve
in the cervical region (C1 to C5) and giving
origin to spinal root of accessory.

43. 2.Cell groups in the posterior grey
column
• Arranged into four longitudinal columns
 Substantia gelatinosa (of Rolandi),
 Nucleus proprius,
 Nucleus dorsalis (or Clarke's column)
 Visceral afferent nucleus.

45. 2.A.Substantia gelatinosa
• Present at the apex of the posterior grey column
• Extended throughout the length of spinal cord.
• Composed of small Golgi type II neurons
(interneurons).
• Receives the afferent fibres of the lateral division of
the posterior nerve roots.
• Conveying the pain and temperature sensations.
Substantia gelatinosa is continuous above with the
nucleus of spinal tract of the trigeminal nerve.

46. 2.B.Nucleus Proprius
• Group of large nerve cells situated anterior to the
substantia gelatinosa
• Form main bulk of cells present in the posterior
grey column.
• Extends along the whole length of the spinal cord
• Receives the fibres from posterior white column
that are associated with the sense of position
and movement (proprioception), two-point
discrimination, and vibration.

47. 2.C.Nucleus dorsalis (Clarke's column)
• Occupies the medial part of the base of the
posterior grey column
• Projecting into the posterior funiculus .
• Extends from C8 to L2/L3
• Receives proprioceptive afferents (muscle
and joint sense) and exteroceptive afferents
(touch and pressure) from trunk and lower
limb

48. 2.D.Visceral afferent nucleus
• Located lateral to the Nucleus dorsalis.
• Extends from T1 to L2 and from S2 to S4
• Receives visceral afferent from dorsal nerve
roots

49. 3.Cell groups in the intermediate
(lateral) grey column
Intermediolateral
Intermediomedial.
3.A.Intermediolateral nucleus :
• Extends from T1 to L2 and gives origin to
preganglionic fibres of the sympathetic NS
(Thoracolumbar outflow)
• Leave the cord along with anterior nerve
roots

50. 3.B.Intermediomedial nucleus
• Extends from S2 to S4.
• Gives origin to preganglionic fibres of
parasympathetic nervous system (sacral
outflow),
• Pass out through the anterior nerve roots of
the corresponding sacral nerves.

51. Laminar architecture of grey matter
(Rexed laminae)
• Cyto-architecture of grey mater of spinal cord
is alternatively divided into 10 zones or
laminae by Rexed.
• Numbered consecutively by Roman numerals
• Starting at the tip of the posterior horn and
moving ven-trally into the anterior horn.

52. • Rexed laminae provides information about the localization
of terminal degenerating fibres after section of posterior
nerve roots or descending nerve tracts.

53. Bror Rexed.
• Bror Rexed (1914 - 2002)
• Swedish neuroscientist
• Professor at Uppsala
University.
• Best known for his
development of the system
as Rexed laminae,
• Also known for his involvement
in the "du-reformen" of
the Swedish language.

54. White Matter
• Surrounds the central ‘H-shaped mass of grey
mater
• Consists of myelinated nerve fibres
• Types of fibres in the white matter:
Sensory fibres
Motor fibres
Association fibres

55. Sensory fibres
• Central processes of primary sensory neurons
of the posterior root ganglia.
• Enter the spinal cord and ascend or descend
for varying lengths.
• Ascending fibres from the nuclei of spinal grey
columns that convey sensory modalities to the
higher centres.

56. Motor fibres
• Descending fibres from higher centres
(supraspinal levels) to the spinal cord
• Nerve fibres of anterior and lateral horn cells
that go to the motor roots of the spinal
nerves.
Association fibres
• Originate and end within the spinal cord
• Interconnecting the neurons of the same
segment or of different segmental levels.

57. Division of White matter

58. Division of White matter
• Arranged in form of columns or funiculus
• Anterior column
• Poserior column
• Lateral column

59. Divisions of white matter
Posterior: betwn the posterior median septum and
the posterior horn.
Lateral: between the anterior and posterior horns.
Anterior: between the anterior median fissure and
the anterior horn(joined by the white commissure)
Columns are made up of tracts which are…
Ascending (sensory),
Descending (motor)
Intersegmental (association).

60. Blood supply
• Anterior spinal artery.
• 2 posterior spinal arteries.
• Segmental arteries.
The anterior spinal artery supplies the anterior
two-third of the cord, while two posterior
spinal arteries together supply the posterior
one-third of the cord.

62. Anterior spinal artery
• Formed by the union of two small spinal
branches of the right and left vertebral
arteries in the upper cervical canal.
• Runs caudally in the anterior median fissure
of the spinal cord
• Terminates along the filum terminale.

63. Posterior spinal arteries
• Each arising as a small branch from either the
vertebral or posterior inferior cerebellar
artery(PICA).
• Artery runs down on the posterolateral aspect
of the cord in the posterolateral sulcus along
the attachment of posterior nerve roots
• Divides into two collateral arteries along the
medial and lateral sides of the posterior nerve
roots.

64. Blood supply-Spinal cord
• There are five longitudinal arteries around the
spinal cord.
• Arteries are reinforced by the segmental arteries
to form 5 longitudinal arterial trunks.
• Arterial trunks communicate around the cord
forming a pial plexus, the arterial vaso-
corona/arteriae coronae.
• Arteriae coronae give peripheral branches which
supply the superficial regions of the cord

66. Segmental arteries
• They are spinal branches of …
 Deep cervical,
 Ascending cervical,
 Posterior intercostal,
 Lumbar
 Lateral sacral arteries.
• Reach the spinal cord, as the anterior and posterior
radicular arteries along the corresponding roots of the
spinal nerves respectively
• Nourish the nerve roots.

68. Radicular arteries
• 8 anterior and 12 posterior
• Regular reinforcement to the anterior and
posterior spinal arteries to form 5 longitudinal
arterial trunks.
• Anterior arteries are larger but less in no. than
the posterior.
• Frequently anterior arteries arise at the first (T1)
• Eleventh thoracic (T11) segmental levels are very
large and termed arteria radicularis magna
(arteries of Adamkiewicz).

69. Radicular (segmental) arteries
• Are end arteries, more important in the
vascular supply of the cord
• If blocked the area supplied by artery will be
damaged.

70. Venous drainage
• In form of six longitudinal venous channels around the
cord
 Two median longitudinal, one in the anterior median
fissure and the other in the posteromedian sulcus.
 Two anterolateral, one on either side, posterior to the
anterior nerve roots.
 Two posterolateral, one on either side posterior to the
posterior nerve roots.
• These longitudinal venous channels communicate with
the internal vertebral venous plexus and drained by
veins which leave through the intervertebral foramina
to empty into the vertebral, posterior intercostal,
lumbar and lateral sacral veins.

72. The End
Spinal Cord- Part 1
Thank You
27.09.2016