Transcript SPHS 4050, Neurological Bases, PP 09a

09a
Transition to cranial nerves and
the pathways associated with
them
See pp. 360-370 in book
What parts of the PNS are most
proximal to the CNS?
• Spinal nerves
• Cranial nerves
CNS
Groups/ Aggregations /Cluster of
neuronal cell bodies
(gray matter)
Bundles of (myelinated) axons
with common origins and
destinations
(white matter)
Cortex (e.g. cortex of cerebrum, cortex
of cerebellum)
Nerve tract, tract, nerve pathway,
pathway (e.g. spino-cerebellar
tract)
Nuclei (e.g. nucleus gracilis, nuclei that
make up the thalamus and basal
ganglia)
Fasciculi (e.g. fasciculus gracilis)
Central gray matter of spinal cord
PNS
Ganglia (e.g. dorsal root ganglia;
trigeminal ganglia)
Nerves (e.g., spinal nerves, cranial
nerves, and their branches)
• Spinal nerves
– Described as mixed
nerves: carry both
sensory (afferent)
and motor (efferent)
fibers of trunk and
limbs
• Somatic afferent and
efferent
• Autonomic/visceral
afferent and efferent
• Spinal peripheral nerves (cont.)
– Sensory: posterior
• Dorsal root connects to
dorsal horn of gray matter
• GSA (general somatic
afferent) and GVA
(general visceral afferent)
– Motor: anterior
• Ventral root connects from ventral horn of gray
matter: beginning of “final common pathway” of
somatic motor system, contains lower motor neurons
• GSE (general somatic efferent) and GVE (general
visceral efferent)
Now, transition to cranial nerves
• Compare cranial nerves to spinal nerves
– Some cranial nerves are motor only, and
some are sensory only. (Only some of the
cranial nerves are mixed, like the spinal
nerves are)
– Some of the cranial nerves do not carry both
somatic and autonomic nervous system
functions; the spinal nerves carry both
somatic and autonomic nervous systems
functions
• Cranial nerves
– Some are sensory only,
some are motor only, and
some are mixed.
– All have some relation to
speech, language,
hearing, communication,
and/or swallowing
– Largely voluntary, but
some include autonomic
and reflexive pathways
– Organized in pairs
– Each pair designated by
name and Roman numeral
Cranial
nerves have
associated
nuclei,
which are
organized in
clusters and
columns
Damage to nuclei can mimic damage to the
cranial nerves themselves
Focus in on cranial nerves (there are 12 pairs)
– Roots connect to CNS
• brainstem
• uppermost spinal cord
– Exit brain and pass through skull to reach the
sense organs or muscles of head and neck with
which they are associated
– Relatively unprotected (susceptible to damage)
– All twelve relevant to speech, language,
communication hearing, &/or swallowing
– When cranial nerves or their associated nuclei are
damaged, this can be one of the causes of:
• dysarthria (speech motor disorder)
• dysphagia (swallowing disorder)
Steps in learning cranial nerves
• Find location of cranial nerves
• Learn the names associated with each
cranial nerve
• Overview of organization of cranial nerves
• Details of each cranial nerve
– Name and location
– Function
– Clinical tests of function
Cranial
Nerves –
Ventral view
Dfdf
Cranial
Nerves –
Dorsal view
Trochlear
Nerve (IV)
Cranial
Nerves –
Lateral view
Names of the cranial nerves: A
friendly mnemonic…
Some
cranial
nerves
sensory,
some
motor,
and
some
both
Relationship to
speech,
hearing, facial
expression,
swallowing…