The Spinal Cord
Chapter 13
I. Gross Anatomy of the Spinal Cord
A.
~18 inches long by ~1/2 inches wide
B.
See handout for diagram of anatomy
Find and know these terms:
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Posterior medial sulcus
Anterior median fissure
Cervical & lumbar enlargements
Conus medullaris
Filum terminale (“terminal thread”)
Dorsal root ganglion
Dorsal & ventral roots
Spinal nerves
Cauda equina (“horse tail”)
C.
Spinal Meninges
1. a series of specialized membranes that
provide physical stability and shock absorption
2. Blood vessels lie within the layers to deliver
oxygen and nutrients.
3. are continuous with the cranial meninges
surrounding the brain
4. Bacterial/viral infection can cause meningitis
a)
inflammation of the meninges
b)
can disrupt circulation of cerebrospinal fluid (CSF)
c)
can be deadly
d)
Meningitis & college… should you get vaccinated?
5. Three meningeal layers
a)
Dura Mater (“hard mother”)
i.
tough, fibrous, outermost covering
ii. padded from vertebrae by adipose tissue in the epidural
space
►
Injecting an anesthetic into this space will affect
spinal nerves near the injection site.
►
May be used in the lower lumbar or sacral region
during childbirth.
b)
Arachnoid (“spider”)
i.
middle layer
ii. encloses the subarachnoid space
►
contains a network of collagen and
elastic fibers (arachnoid trabeculae)
►
filled with CSF
- shock absorption
- diffusion of nutrients and wastes
►
Spinal taps occur here
- withdrawal of CSF with a hollow needle in the
lower lumbar region
- used to diagnose problems like meningitis
c)
Pia Mater (“delicate mother”)
i. innermost layer
ii. contain blood vessels that service
the spinal cord
i. bound firmly to the underlying
neural tissue
II. Sectional Anatomy of the Spinal Cord
A.
See handout for diagram of anatomy
B.
Organization of Gray Matter
1. Reminder: gray matter= unmyelinated neuron
cell bodies
2. Functional groups:
a)
b)
Sensory nuclei
Motor nuclei
C.
Organization of White Matter
1. Reminder: white matter = myelinated axons
2. Each side is divided into three regions called
columns or funiculi:
a)
b)
c)
Posterior white columns
Anterior white columns
Lateral white columns
3. Each column contains tracts (bundles of
axons):
a)
b)
Ascending tracts – sensory info
Descending tracts – motor info
III. Spinal Nerves
A.
Each spinal nerve is covered by a series of
connective tissue layers
1. Epineurium- outermost layer
2. Perineurium
a)
b)
c)
middle layer
surrounds bundles of axons (fascicles)
contains blood vessels
3. Endoneurium
a)
b)
innermost layer
surrounds individual axons
B.
See handout for diagram of anatomy
C.
Dermatomes:
1. a specific region of the body surface that is
monitored by a pair of spinal nerves
2. Damage or infection of a spinal nerve will
produce a loss of sensation in the specific skin
region
►
example: Shingles (ask Ms. Schroeder!)
D.
Nerve Plexuses (“nerve braid”)
1. complex, interwoven network of nerves
2. Three major plexuses:
a)
Cervical plexus- spinal nerves C1-C5
b)
Brachial plexus- spinal nerves C5-T1
c)
Lumbosacral plexus- T12-S4
The Brain
Chapter 14
I. Introduction to the Organization of the Brain
A.
Contains ~98% of body’s neural tissue
B.
Weighs ~3lbs & has a volume ~1200 cm3
1. Can vary from 750 cm3 – 2100 cm3
2. Men’s brains are ~10% larger than females
3. No correlation exists between size &
intelligence
C.
Preview of Major Regions & Landmarks
1. Cerebrum
a)
Largest in size of all the regions
b)
Consists of paired cerebral hemispheres
c)
Conscious thoughts, sensations, intellect, memory
& complex movements originate here
d)
Surfaces are highly folded and covered by neural
cortex, a superficial layer of gray matter
(cerebral cortex)
2. Cerebellum
a)
Second largest in size
b)
Also divided into hemispheres, partially hidden by
the cerebral hemispheres
c)
Adjusts ongoing movements on the basis of
comparisons between new and old sensations
3. Diencephalon
a)
Links the cerebral hemispheres and the brain stem
b)
Left & right thalamus
►
c)
Contain relay and processing centers for sensory
information
Hypothalamus
i.
Floor of diencephalon
ii.
Connected to the pituitary gland
iii. Involved with emotions, autonomic function & hormone
production
4. Brain stem
a)
Contains a variety of important processing centers
that relay information headed to or from the
cerebrum or cerebellum
b)
Includes:
i. Mesencephalon
►
Contain sensory nuclei that process visual & auditory
information & control reflexes for these stimuli
ii. Pons (“bridge”)
►
Connects cerebellum to brain stem
►
Contains tracts, relay centers & nuclei involved with
somatic & visceral motor control
iii. Medulla Oblongata
►
Connects brain to spinal cord
►
Relays sensory information to the thalamus and the
brain stem
►
Contains major centers concerned with regulation of
autonomic function (heart rate, blood pressure,
digestion)
D.
Ventricles of the Brain
1. Chambers filled with CSF and lined by
ependymal cells
2. CSF continually circulates between the
ventricles, central canal & subarachnoid space
3. 4 chambers:
1st Lateral Ventricle
b) 2nd Lateral Ventricle
c) 3rd Ventricle - in the diencephalon
d) 4th Ventricle
a)
II. Protection & Support of Brain
A.
Brain is protected by:
1. Cranial bones
2. Cranial meninges
a)
same 3 from spinal cord are continuous in the
brain w/ some differences
i.
Dura mater has 2 layers w/ the superficial layer fused w/
the periosteum of the cranial bones
ii. No epidural space
iii. Dural layers are separated by a small gap & in some
places large channels called dural sinuses
b)
Functions of the Cranial Meninges
i.
Tough, fibrous dural folds hold brain in position
ii.
CSF acts as a shock absorber
3. Cerebrospinal fluid
a)
Produced by ependymal cells in the choroid plexus
b)
~150 ml of CSF in the nervous system
c)
Entire volume of CSF is replaced every 8 hrs
4. Blood-brain-barrier