Spinal cord

1. SPINAL CORD
By: Maryam Bahrami

2.  The spinal cord is the extension of
the CNS below the level of the
skull. It is an elongated structure
that is located in the vertebral
canal.
 It stretches from upper border of
the foramen Magnum to the
intervertebral disc between the
first and second lumbar vertebrae.
spinal cord

3.  At birth, this end is at the level of
the third lumbar vertebra.
 With increasing age, the vertebral
column and dura lengthen more
rapidly than the neural tube, and
the terminal end of the spinal
cord gradually shifts to a higher
level.

4.  The spinal cord has two
enlargement:
 Cervical enlargement (C4-T1)
 Lumbar enlargement (L2-S3)
 Conus medularis

5. Features of the outer surface
of the spinal cord:
 Anterior Median Fissure
 Posterior Median Fissure
 Anterolateral sulci
 Posterolateral sulci
 Linea splendens

6.  31 pairs of spinal nerves:
 8 cervical
 12 thoracic
 5 lumbar
 5 sacral
 1 coccygeal

7.  Dorsal root – sensory fibres
 Ventral root – motor fibres
 Dorsal and ventral roots join at
intervertebral foramen to form the spinal
nerve
 Spinal segment

9. Cauda equina

10. Meninges of spinal cord
Spinal cord surrounded by 3 layers of meniges:
 dura mater
 arachnoid
 pia mater

11.  Filum terminalis
 Lumbar cicterna
 Coccygeal ligament

12.  Epidural space
 Subdural space
 Subarachnoid space

13. Lumbar Puncture

14. Denticulate ligament

15. Internal organization Of The Spinal Cord
Each spinal segment consists of central gray and peripheral white matters.
Gray Matter
 H-shaped
 anterior horns
 poster horns
 lateral horns
 Anterior horns
 Head
 Base
 Poster horns
 Head
 Base
 neck

17. White Matter
It is divided into 3 large funiculus on each side:
 Anterior funiculus :
lies between the ant. median fissure & the Anterolateral sulci.
 Posterior funiculus :
lies between the post median septum & the posterolateral sulci.
 Lateral funiculus :
lies between the posterolateral sulci and the Anterolateral sulci.
 Fasciculus gracilis
 Fasciculus cuneatus

18. spinal cord commissures:
 Gray commissure
 White commissure

19. Gray matter and nuclei

20. Nuclei of the anterior horn
(motor)
are grouped into 3 groups of
motor nuclei:
1. Medial group:
o found in all segments of the spinal
cord (Except L5-S1)
o All of thorasic segments and L1-
L3/4:
• Dorsomedial
• Ventromedial
o C1
• Dorsomedial
o All of cervical segments and S2-Co
• Ventromedial
o innervating the skeletal muscles of
the neck & trunk.

21. 2. Central group:
present in some cervical &
lumbosacral segments
• Phrenic nucleus (C3-C5 segments)
• Accessory nucleus (C1-C5/6
segments)
• Lumbosacral nucleus ( L2-S1
segments)
3. Lateral group:
o present in the cervical &
lumbosacral segments
• Ventrolateral nuclei
• Dorsolateral nuclei
• Retrodorsolateral nuclei
o innervating the skeletal muscles of
the limbs.

22. Nuclei of the posterior horn
1. Posteromarginal nucleus
2. Substatia gelatinosa
3. Nucleus Proprius

23. 4. Clark’s/ dorsal nucleus
o situated at the base of the
posterior gray column in the
thoracic & upper lumbar region
only(C8-L3)
o The cells are associated with
proprioceptive impulses
o Its axons ascend in the lat.
column of the same side
forming the posterior
spinocerebellar tract
5. nucleus centrobasalis
Lower cervical segments and
lumbosacral segments

24. 6. Intermediate cell column
(visceral afferent nucleus)
o situated at T1-L2 and S2-S4
o The cells are associated
with autonomy system
probably

25. III. Nuclei of the Intermediate gray
Present in the segment from T1 to L2/3
and S2-S4
o T1 to L2/3 segment
• Intermediomedial
• Intermediolateral (lateral horn)
o S2-S4
• Sacral parasampathetic gray column

26. White Matter
 Anterior funiculus
 Posterior funiculus
 Lateral funiculus
 Fasciculus gracilis
 Fasciculus cuneatus

27.  Spinal tracts

28. PATHWAYS IN WHITE MATTER
the white matter contains 5 types of nerve fibers:
 Afferent fibers
 Long ascending fibers
 Long descending fibers
 Intersegmental & Intrasegmental fibers(propria fiber)
 Efferent fibers

29. Formation of the fasciculus gracilis and cuneatus

31.  Septomarginal tract
 Comma tract

32. 1.Lateral Spinothalamic Tract
• Transmit impulses from pain &
temprature receptor.

33. 2.Anterior Spinothalamic Tract
 Transmit impulses from light
touch & pressure receptor.

34. 4. Anterior Spinocerebellar Tract
5. Posterior Spinocerebellar Tract
6.Cuneo cerebellar tract

35. 7. Spinotectal tract
spinovisual reflexes

36. 8. Spino-olivary tract
indirect pathway to cerebellum

37. 9. Spinoreticular tract
info from muscles, joints & skin to reticular
formation
10. Spinovestibular tract

38. Descending Fiber Systems
Pyramidal tract:
Upper Motor Neurons
 Are the nerve fibers that descend in the white matter from
different supraspinal nerve centers
 provide numerous separate pathways that can influence motor
activity.
Lower Motor Neurons
 Are the motor neurons situated in the anterior gray columns of
the spinal cord sending axons to innervate skeletal muscle
 constitute the final common pathway to the muscles.

39. 1. Corticospinal Tract

40. 2. Rubrospinal tract:
 Arises from the red nucleus &
crosses to the opposite side
 Descends in the lat. column of
the spinal cord
Function:
 facilitates the activity of flexor
muscles

41. 3. Tectospinal Tract:
 Arises from the sup. colliculus of
midbrain
 Crosses to the opposite side
 Descends in the ant. column of
the spinal cord
Function
concerned with reflex postural
movements in response to visual
stimuli

42. 4. Vestibulospinal Tract
 Arises from the lat-vestibular nucleus in
the pons
 majority of its fibres are uncrossed
 Descends in the ant. column of the
spinal cord
Function:
is concerned with the postural activity
associated with balance.

43. 5. Reticulospinal Tract

44. 6. Olivospinal Tract
7. Medial longitudinal fasciculus(MLF)

45. Blood Vessels of the Spinal Cord: Arteries

47. Blood Vessels of the Spinal Cord: Veins

48. THANKS