1. Biology 322 Human Anatomy I
Spinal Cord

2. Human Central Nervous System
Starts as a groove which becomes a hollow tube in the embryo;
Remains hollow & fluid-filled
throughout life;
These fluid-filled spaces form the ventricles of the brain and the central canal of the spinal cord.
Cranial end of this hollow tube enlarges & folds to form brain and its various parts
Caudal end of this hollow tube does not enlarge or fold; Develops into spinal cord

3. = = Central Brain Nervous Spinal cord System
Nerves which carry information into and out of the brain and spinal cord
Central
Nervous
System =
Peripheral
Nervous
System =

4. White Matter Gray Matter Coronal Section of Brain
Cross Section of Spinal Cord

6. Embryology of nervous system

7. Spinal cord surrounded by 3 layers of connective tissue:
Pia Mater
Arachnoid Mater
Dura Mater

8. Subarachnoid Space
Subdural Space
Epidural Space
(Vertebrae)
Pia Mater
Arachnoid Mater
Dura Mater

9. The spinal cord is protected in three ways:
1) Vertebrae (bone)
2) Meninges
Pia Mater
Arachnoid Mater
Dura Mater
3) Floats in cerebrospinal
fluid in subarachnoid
space

10. Cerebrospinal fluid produced within ventricles by choroid plexus.
Exits from fourth ventricle through median aperture and two lateral apertures into the subarachnoid space surrounding brain and spinal cord
Reabsorbed into blood through arachnoid villi on surface of brain.
Cerebrospinal fluid also passes from 4th ventricle of the brain into the central canal of the spinal cord.

11. Posterior Median Sulcus
Central Canal
Embryology of nervous system
Anterior Median Fissure

12. Recall: In brain and spinal cord
Gray Matter: Nervous tissue of the CNS consisting of neuron cell bodies, their supporting glia, and unmyelinated axons & dendrites.
White Matter: Nervous tissue of the CNS consisting of myelinated axons & dendrites and their supporting glia
White Matter
Gray Matter

13. Gray Matter of Spinal Cord
Dorsal (Posterior) Horn: Cell bodies of neurons which receive afferent information from spinal nerves and send it toward the brain
Lateral Horn: Cell bodies of neurons which receive efferent information from the brain and send it to smooth myocytes, cardiac myocytes, and glands (autonomic motor innervation)
Embryology of nervous system
Ventral (Anterior) Horn: Cell bodies of neurons which receive efferent information from the brain and send it to skeletal myocytes (somatic motor innervation)

14. Gray Matter of Spinal Cord
Connecting these horns of gray matter on the right and left sides of the spinal cord is the gray commissure. This allows both sensory and motor information to be shared between the two sides of the spinal cord, and thus the two sides of the body. ( )

15. White Matter of Spinal Cord
Myelinated axons carrying information between brain and gray matter of spinal cord (both directions).
Dorsal (Posterior) Column:
Lateral Column:
Ventral (Anterior) Column:
Embryology of nervous system
Within each column, axons with same functions organized into bundles called tracts

16. That white matter is formed by the axons of both motor neurons and sensory neurons which are grouped into “tracts”

18. Individual tracts of the spinal cord are described in your Saladin text.
You should be able to describe, in moderate detail, at least one ascending tract and one descending tract:
Where it begins
Where it ends
If it decussates (crosses to opposite side)
Where it is located in the spinal cord
What type of information it carries
What would happen if it were damaged

19. Spinal cord gives rise to spinal nerves.
A pair of spinal nerves (one on
each side) exits between each
pair of vertebrae from the atlas
(cervical 1) to the first vertebra
of the coccyx

20. Each nerve connects with spinal cord through two roots:
Dorsal (posterior) root
Carries afferent
information into
dorsal horn of gray
matter
Ventral (anterior) root
Carries efferent
information away
from ventral horn
of gray matter

21. Spinal nerves named according to which vertebrae they pass between:
8 cervical nerves
12 thoracic nerves
5 lumbar nerves
5 sacral nerves
1 coccygial nerve
Levels of the spinal cord named according to which spinal nerve carries information in/out of it.
Embryology of nervous system

22. Spinal nerves named according to which vertebrae they pass between:
8 cervical nerves
12 thoracic nerves
5 lumbar nerves
5 sacral nerves
1 coccygial nerve
Levels of the spinal cord
named according to which
spinal nerve carries
information in/out of it.
Thus: Spinal cord level "cervical 5" is defined as the region where spinal nerve "cervical 5" connects
Embryology of nervous system

23. Months before you were born, your spinal cord reached all the way through your sacrum, but as you continued to develop it grew less quickly than the vertebrae which surround it.
At birth, your conus medullaris was at lumbar vertebrae 3 or 4. It now lies between lumbar vertebrae 1 and 2.
That means that dorsal
Roots and ventral roots of
the spinal nerves must
extend inferiorly to reach
the proper intervertebral
foramina, forming the
cauda equina which is in
the subarachnoid space.