Sunday, September 25, 2011
This topic will discuss about the Organization of the Nervous System – this will help some student to understand the nervous system organization.
ANATOMICAL DIVISION
1. CNS
- Brain
- Spinal cord
2. PNS
- Cranial nerves, except CN I
- Spinal nerves – origin: spinal cord
- Associated ganglia
ª Collection of nerve cell bodies:
- CNS: nuclei/nucleus
- Outside the CNS: ganglion / ganglia
3. ANS – constituent part of the CNS and PNS
a. Parasympathetic
- Origin: Cranio-sacral
- Cranial – CN 3, 7, 9 & 10
- Sacral – sacral cord levels and sacral spinal nerves 2, 3 & 4
b. Sympathetic
- Origin:Thoraco-lumbar
- Arises from the spinal cord – T1-L2 or L3
- Forms the sympathetic trunk with its ganglia
FUNCTIONAL DIVISION
1. Sensory / Afferent
- Receives and transmits impulses to the CNS
2. Motor/ Efferent
- Impulses originate from the CNS
ª Gray matter / cerebellar cortex / cerebral cortex – collection of nerve cell bodies
ª White matter – collection of myelinated axons (tracts,fasciculus,peduncle, columns)
** note: in spinal cord – gray matter is found at the center while white matter is at the periphery
TYPES OF FIBERS
1. Commissural
- Helps communicate one hemisphere to another
- i.e. corpus callosum
2. Association
- Communicates within the same hemisphere
a. Long
b. Short
3. Projection
- Need to communicate (in the gray matter) involving several fibers in different locations
- i.e. corona vadiata
TRACTS – fibers with common origin and destination
1. Ascending
- Spinothalamic tract
- Sensory
2. Descending
- Corticobulbar tract
- Corticospinal tract
- Motor tract
ª White matter of the spinal cord
- Fasciculus – cervical part of the cord
§ Ganglia – upper
§ Cunneatus – lower
- Funniculus – anterior, lateral, dorsal
>> Additional Info (from Dr. Elma) – in order to identify which side of the spinal cord is dorsal or ventral
àseen cross sectionally the spinal cord has:
- Ventral median fissure – deeper
- Dorsal median sulcus – shallow (Posterior)
Glial cells / Neuroglia
- Astrocytes
- Oligodendrocytes
- Microglia – macrophage system
- Macroglia – collective term for astrocytes and oligodendrocytes
- Ependymal cells – lining the central canal of spinal cord
Homunculus
- Motor – bigger hands (left)
- Sensory – bigger lips and arms (right)
Read more: http://healthmad.com/conditions-and-diseases/organization-of-the-nervous-system/#ixzz1Ywi8wI94
Sunday, September 25, 2011 by pinoy maker · 0
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