the gross structure of spinal cord, the transverse section of spinal cord , grey and white matter, dorsal root ganglion, formation of spinal nerve, conus medullaris, filum terminal, cauda equana, meningeal layer covering spinal cord, nuclei of anterior horn of gray mater, cell bodies of posterior horn of gray mater, tracts of white matter of spinal cord, ascending and descending tract of spinal cord,

1. SPINAL CORD
STRUCTURE
Dr Sana Yaseen
Anatomy department
KIMS

2.  INTRODUCTION
 Origin:foramen Magnum
 Terminates at:
L1/2 vertebral level-
adults
L3- children
 31 pairs of spinal nerves
(mixed)
 Cervical & lumbar
enlargements

3. Spinal nerves & cord
 31 pairs with anterior and
posterior roots
 C1 often doesn’t have
posterior root
 Spinal cord enlarged in C5
– T1 and L2 – S3 levels

5. Inferiorly spinal
cord tappers off
into
CONUS
MEDULLARIS

7. The 3 Meningeal Layers
• Dura mater:
– outer layer of spinal cord
– subdural space:
• between arachnoid mater
and dura mater
• Arachnoid mater:
– middle meningeal layer
– subarachnoid space:
• between arachnoid mater
and pia mater
• filled with cerebrospinal fluid
(CSF)
• Pia mater:
– inner meningeal layer

8. MENINGEAL COVERING OF SPINAL
CORD

10. TERMS
 Conus medullaris – terminal portion of the spinal cord
 Filum terminale – fibrous extension of the pia mater; anchors
the spinal cord to the coccyx
 Denticulate ligaments – delicate shelves of pia mater; attach
the spinal cord to the vertebrae
 Spinal nerves – 31 pairs attach to the cord by paired roots
 Cervical nerves are named for inferior vertebra
 All other nerves are named for superior vertebra
 Cervical and lumbar enlargements – sites where nerves
serving the upper and lower limbs emerge
 Cauda equina – collection of nerve roots at the inferior end of
the vertebral canal

11. Conus medullaris
Filum terminale
Cauda equina
Dura mater
External Spinal Cord

13.  Paired denticulate
ligaments:
 extend from pia mater to
dura mater
 stabilize side-to-side
movement
 Blood vessels:
 along surface of spinal
pia mater
 within subarachnoid
space

15. Cross-Sectional Anatomy of the Spinal Cord
 Anterior median fissure – separates anterior
funiculi
 Posterior median sulcus – divides posterior
funiculi

16. ANTERIOR MEDIAN FISSURE
POSTERIOR MEDIAN SULCUS
ANTERIOR GREY COMMISURE
POSTERIOR GREY COMMISURE
CENTRAL CANAL
ANTERIOR HORN
OF SPINAL CORD
POSTERIOR HORN
OF SPINAL CORD

17. LATERAL HORN OF S.C
POSTEIOR HORN OF S.C
ANTERIOR HORN OF S.C
POSTERIOR GREY COMMISURE
ANTERIOR GREY COMMISURE
ANTERIOR/ VENTRAL / MOTORROOT OF S.C
POSTEIOR/ SENSORY ROOT GANGLION
LATERAL
FUNICULI
POSTERIOR FUNICULI
ANTERIOR
FUNICULI
POSTEIOR/ SENSORY ROOT OF S.C
SPINAL NERVE

21. Cross-sectional gray mater
 Is seen as H shaped/ butterfly wing with anterior and
posterior gray columns/ horns united by thin anterior and
posterior gray commissure with centrally present central
canal.
 Gray matter (cell bodies, neuroglia, & unmyelinated
processes)
 Posterior horns (sensory, all interneurons)
 Lateral horns (autonomic, T1-L2)
 Anterior horns (motor, cell bodies of somatic motor neurons)
 Spinal roots
 Ventral (somatic & autonomic motor)
 Dorsal (DRG)

22.  In thoracic and upper lumbar segments small lateral gray
column is present.
 Amount of gray mater present at any given level of spinal
cord is related to the amount of muscle innervate at that level
such as greatest in lumbar and sacral segements.

23. Gray Matter: Organization
 For practical purpopse
the nerve cells of
anterior grey column
may be divided into 3
groups,
 MEDIAL
 CENTRAL
 LATERAL
POSTERIOR MARGINAL
NUCLEUS
SUBSTANTIA GELATINOSA
NUCLEUS PROPRIUS
NUCLEUS DORSALIS
INTERMEDIOLATERAL
CELL GROUP
INTERMEDIOMEDIAL
CELL GROUP
MEDIAL GROUP
LATERAL GROUP
DORSAL
HORN
INTERMEDIATE
VENTRAL HORN
 the nerve cells of posterior grey
column divided into 4 groups,
 Substantia gelatinosa
 Nucleus proprius
 Nucleus dorsalis
 Visceral afferent group

24.  MEDIAL GROUP:
 Present in most of the segment
 Innervates sk. Msl of neck and trunk & intercostal and
abdominal musculature
 MIDDLE GROUP
Cervical segment:
 Innervates diphragm
(phrenic nerve) C3,4,5
 C1-5/6: innervates
sternocleidomastoid,
trapezius msl
 Forms spinal part of
accessory nerve
Lumbosacral segment:
 L2-S1
LATERAL SEGMENT
 Present in cervical and lumbosacral segment
 Innervates sk. Msl of upper and lower limbs

25.  SUBSTANTIA GELATINOSA
 Apex of posterior gray column
 Throughout spinal ord
 Golgi type II neurons
 Recieves afferent for Pain-Temp- Touch
 NUCLEUS PROPRIUS
 Lies anterior to substantia gelatinosa
 Recieves afferent of sense of position,
movement , two point discrimination,
vibration
 VISCERAL AFFERENT
 T1-L3 segment
 Recieves visceral afferent from
organs
 NUCLEUS DORSALIS/ CLARK’S COLUMN
 Base of posterior grey column
 C8-L4
 Associated with proprioceptive ending, (neuromuscular spindles & tendon
spindles)

26. Grey Matter Organization
Anterior
Intermediate
Posterior
Motor Groups
Lateral
Medial

27. Grey Matter Organization:
Lateral Grey Horns: T1 –
L2/3
AKA
Intermediolateral
Cell Column

28. Grey Matter Organization:
Posterior Cell Column
Dorsomarginal nucleus
Substantia gelatinosa
Nucleus proprius
Nucleus dorsalis
(Clarke’s column)

29. LATERAL GREY COLUMN
 Presnt in T1- L2/3 segments and S2,3 segaments
 Cells are small and the axons in thoracic and upper
lumbar segments are preganglionic sympathetic
fibers
 Axons in sacral segments are pre ganglionic para
sympathetic fibers

30. WHITE MATER
 Fibers run in three directions – ascending, descending, and
transversely
 3 funiculi (posterior, lateral, anterior)
 Each funiculus contains several fiber tracts
 Fiber tract names reveal their origin and destination
 Fiber tracts are composed of axons with similar functions
 Consist of “tracts” containing similarly functional axons
• All tracts are paired
• Most cross over (decussate) at some point
• Most exhibit somatotopy (superior part of the tracts are
more lateral that inferior body regions)
• Most consist of a chain of 2 or 3 successive neurons

31. White Matter: Pathway
Generalizations

33. Spinal Cord
 Central gray nuclei
and outer white
matter (tracts)
Cell bodies Ascending
tracts
Descending
tracts
Peripheral
nerve
fibers

34. External Structure – Spinal
Cord
Anterior Median Fissure
Posterior Median Sulcus
Lateral sulci

35. Internal Structure – White
Matter
Funiculi
Posterior
Lateral
Anterior

36. White Matter Organization:
Ascending Pathways
Posterior Columns
Posterior &
Anterior
Spinocerebellar
Tracts
Lateral &
Anterior
Spinothalamic
Tracts

37. White Matter Organization:
Descending Pathways
Rubrospinal
Tract
Lateral
Corticospinal
Tract
Anterior
Corticospinal
Tract
Vestibulospinal
Tracts
Reticulospinal
Tracts

38. White Matter Organization:
Intersegmental Pathways
Lissauer’s
Tract
Intersegmental
Tracts

39. White Matter Organization:
Ascending Pathways
Posterior Columns
L
N
Lateral &
Anterior
Spinothalamic
Tracts

40. White Matter Organization:
Descending Pathways
Legs
Neck
T
A