Download Biology 211 Anatomy & Physiology I

Biology 211
Anatomy & Physiology I
Spinal Cord
Human Central Nervous System
Starts as a hollow tube in the embryo;
Remains hollow & fluid-filled throughout life;
These 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
Embryology of nervous system
Coronal Section of Brain
Cross Section of Spinal Cord
Embryology of nervous system
Spinal cord surrounded by 3 layers of connective tissue:
Mater
Space
Mater
Space
Mater
Space
(Vertebrae)
The spinal cord is protected in three ways:
1)
2)
3) Floats in
Cerebrospinal fluid produced
within ventricles by
Exits from fourth ventricle
through three openings
(apertures or foramina) into the
subarachnoid space.
Two
Surrounds brain & spinal cord.
Reabsorbed into blood
through arachnoid villi on
surface of brain
Embryology of nervous system
Recall: In brain and spinal cord
Nervous tissue of the CNS consisting of
neuron cell bodies, their supporting glia, and unmyelinated
axons & dendrites.
Nervous tissue of the CNS consisting of
myelinated axons & dendrites and their supporting glia
Gray Matter of Spinal Cord
Cell bodies of neurons which
receive afferent information from spinal nerves and send
it toward the brain
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
Cell bodies of neurons which
receive efferent information from the brain and send it to
skeletal myocytes (somatic motor innervation)
White Matter of Spinal Cord
Myelinated axons carrying information between brain and
gray matter of spinal cord (both directions).
Embryology of nervous system
Within each column, axons with same functions organized
into bundles called
Individual tracts of the spinal cord are described on
pages 486 to 490 of your Saladin text (4th ed).
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 deccusates
Where it is located in the spinal cord
What type of information it carries
What would happen if it were damaged
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
Each nerve connects with spinal cord through two roots:
Carries afferent
information into
dorsal horn of gray
matter
Carries efferent
information away
from ventral horn
of gray matter
Spinal nerves named according to
which vertebrae they pass between:
cervical nerves
thoracic nerves
lumbar nerves
sacral nerves
coccygial nerve
Levels of the spinal cord
named according to which
spinal nerve carries
information
in/out of it.
Embryology of nervous system
Spinal nerves named according to
which vertebrae they pass between:
cervical nerves
thoracic nerves
lumbar nerves
sacral nerves
coccygial nerve
Levels of the spinal cord
named according to which
spinal nerve carries
information
in/out of it.
Embryology of nervous system
Thus: Spinal cord level "cervical 5"
is defined as the region where
spinal nerve "cervical 5" connects
Next: Let's follow the spinal nerves distally as they
form the peripheral nervous system.
Embryology of nervous system