Download spinal cord - Dr Magrann

There are 12 pairs of cranial nerves, numbered with Roman numerals.
I Olfactory
II Optic
III Occulomotor
IV Trochlear
V Trigeminal
VI Abducens
VII Facial
VIII Vestibulocochlear
IX Glossopharyngeal
X
Vagus
XI Accessory Nerve
XII Hypoglossal
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I.
OLFACTORY nerves
Transmits the sense of smell.
II. OPTIC NERVE: Transmits visual information from the eye’s retina.
III Occulomotor Nerve: this controls most of the extrinsic muscles of the
eye (that move the eyeball). They also have parasympathetic innervation
in the iris (pupil) and cilliary (controls the lens).
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IV. Trochlear Nerve: supplies one of the extrinsic eye muscles
V. Trigeminal Nerve: This is the main sensory nerve of the face.
It has a large branch that passes through the foramen ovale of the skull.
Problems with CN-5 are called TRIGEMINAL NEURALGIA, which is
excruciating pain in the face from nerve inflammation.
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VI: Abducens controls one of the eye muscles (lateral rectus).
VII Facial Nerve: This innervates the muscles of facial expression and
salivary glands.
A person who cannot blink or smile may have damage to what nerve?
VII Facial Nerve
A person who cannot easily taste sweet, sour, or salty substances has damage
to what nerve? VII Facial Nerve
BELL’S PALSY is damage of the facial nerve Needs to be distinguished
from a stroke.
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VIII. VESTIBULOCOCHLEAR nerve transmits hearing and balance.
IX: GLOSSOPHARYNGEAL
a) signals the pharynx to constrict (along with X) during swallowing.
b) Innervates top of tongue
c) Has baroreceptors
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X Vagus Nerve
a) Parasympathetic supply to organs
b) Moves the larynx during speech
c) Signals pharynx to constrict during swallowing (with CN IX)
.
This is the only cranial nerve that travels into the abdomen.
The majority of the parasympathetic outflow from the head is by the vagus
nerve.
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XI: ACCESSORY NERVE enters the skull through foramen magnum and
leaves through the jugular foramen. It just supplies the shoulder muscles.
XII. HYPOGLOSSAL NERVE (hypo=under; glossal=tongue) - supplies
the under surface of the tongue. Damage causes impairment of speech.
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FORAMEN MAGNUM. It goes to L1-2.
In infants, it ends at L4-5, because it doesn’t grow as fast as the rest of the
body.
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CAUDA EQUINA (“Horse’s tail”), which exit through the intervertebral
foramina.
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The SACRAL PLEXUS is made up of the spinal nerves exiting the spinal
cord from the level of L4 to S5.
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There is a spinal nerve C8, although there is no C8 vertebrae.
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CENTRAL CANAL, GREY MATTER, WHITE MATTER, POSTERIOR MEDIAN
SULCUS, ANTERIOR MEDIAN FISSURE, DORSAL HORN, VENTRAL HORN,
DORSAL ROOT, DORSAL ROOT GANGLION, VENTRAL ROOT, and SPINAL
NERVE
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Ganglion = a group of neuron cell bodies.
Some are motor, some are sensory.
The ganglions in the dorsal root are always sensory.
All ganglia are in the PNS only
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Posterior root ganglion
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Most synapses are in the CNS
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SENSORY NEURONS come in through the posterior root, their cell body is
in the posterior root ganglion, and its axon goes into the posterior horn and
synapses in the grey matter.
It also sends a branch to an area of the white matter called the DORSAL
COLUMN PATHWAY, which goes into the brain (thalamus).
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Thalamus
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LMN’s have their cell body in the anterior horn (of the gray matter), and
their axon goes out the anterior root, and synapses in a muscle.
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Their cell bodies are in the dorsal half of the gray matter in the spinal cord.
They receive signals from the sensory neuron and then synapse on the cell
body of the motor neuron. In this way, the interneurons (sometimes called
association neurons) transmit signals from the sensory pathways to the
motor pathways.
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The complexity of the CNS can be attributed to Interneurons
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Pain and temperature
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Sensory, lower motor, and interneuron forms the SIMPLE REFLEX ARC.
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If you touch a hot stove, the sensory input comes into the spinal cord, the
association neurons send the information to the lower motor neurons, the
muscle contracts, and you take your hand off the stove before your brain
even knows it.
Simple reflex behavior involves three nerves, and no brain involvement.
Reflexes are automatic events.
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They involve both motor and sensory neurons, they are rapid, involuntary,
and they involve multiple synapses.
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KNEE-JERK REFLEX
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SENSORY TOUCH  SPINAL NERVE  POSTERIOR ROOT
GANGLION  POSTERIOR ROOT  POSTERIOR HORN 
TRACT  THALAMUS
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Inside the brain nerves are called tracts; outside the brain, they are called
called nerves (ie optic nerve and optic tract, olfactory nerve and olfactory
tract)
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Upper motor neuron: cell body is in the brain, synapses on a lower motor
neuron (in the spinal cord)
Lower motor neuron: cell body is in the spinal cord, and synapses on skeletal
muscle.
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a plexus.
One of these is known as the brachial plexus (in the armpit; innervates the
muscles of the arm).
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rami, trunks, divisions, cords
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PROPRIOCEPTION neurons measure the amount of force and movement in
muscles and joints
Proprioception nerves travel up the spinocerebellar tract.
Close eyes and touch finger to nose.
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Cannot move hand on own (paralysis) but reflexes work
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