What is the peripheral nervous system?
* The peripheral nervous system consists of nervous tissue outside the brain and the spinal cord.
What types of nervous tissues are found in the peripheral nervous system?
* Nerves and Ganglia
What are the subdivisons of the peripheral nervous system?
*Somatic- involved in voluntary skeletal muscle activities (body wall)
*Autonomic- regulates activities of smooth muscle, cardiac muscle, and glands (most complex) (GI tract)
*Enteric- regulates GI tract activity
What exactly is a nerve?
*Bundles of axons outside CNS, along with associated connective tissues and blood vessels.
*Cranial nerves- arise from the brain
*Spinal nerves- arise from the spinal cord
What is the microanatomical structure of a nerve?
* Three protective tissue coverings
~ Endoneurium: around each axon (with or without myelin)
~ Perineurium: around fascicle of axons
~ Epineurium: around several fascicles, continuous from dura mater of CNS
How many cranial nerves are present in the human body?
* There are twelve pairs that are numbered from anterior to posterior.
~ Pass through foramina in cranial bones
What are the different types of cranial nerves?
1. Sensory
2. Motor
3. Mixed
Sensory
*Carry axons of snesory neurons
~ Periphery to brain
~ Cell bodies in ganglia
Motor
*Predominantly axons of motor neurons
~ Brain to periphery
~ Somatic: innervate skeletal muscle
~ Autonomic: innervate smooth muscle, cardiac muscle, and glands
~ Cell bodies in nuclei within brain
Mixed
*Contain axons of both sensory and motor neurons
Old
Opie
Occasionally
Tries
Trigonometry
And
Feels
Very
Gloomy
Vague
And
Hypoactive
I. Olfactory
II. Optic
III.Oculomotor
IV.Trochlear
V. Trigeminal
VI. Abducens
VII.Facial
VIII.Vestibulocochlear
IX. Glossopharyngeal
X. Vagus
XI. Accessory
XII. Hypoglossal
*S-Sensory
*M-Motor
*B-Both (Mixed Nerve)
Some-Olfactory
Say- Optic
Marry-Oculomotor
Money-Trochlear
But-Trigeminal
My-Abducens
Brother-Facial
Says-Vestibulocochlear
Big-Glossopharyngeal
Brains-Vagus
Mean-Accessory
More-Hypoglossal
Cranial Nerve I: Olfactory
*Sensory
*Functions in sense of smell
~ Carries impulses from odor receptors within olfactory epithelium in nasal cavity
~ Pass through olfactory foramina in cribiform plate of ethmoid bone
~ Synapse in olfactory bulbs with neurons of olfactory tracts
~ E
Cranial Nerve II: Optic
*Sensory
*Functions in sense of vision
~ Carries impulses from rods and cones in retina of eye
~ Pass through optic foramen in orbit
~ Merge to form optic chiasm
- Some cross to other side
- Some stay on same side
~ Optic tracts end in primary visual area
Cranial Nerve III: Oculomotor
*Motor
~ Some axons for proprioception association with eyeball muscles
*Functions in movement of eye
~ Carries somatic motor impulses to four muscles of eyeball and of the upper eyelid
~ Autonomic motor axons adjust shape of lens and size of pupil
Cranial Nerve IV: Trochlear
*Motor
~ Some axons for proprioception associated with eyeball muscles
*Functions in movement of eye
~ Carries somatic motor impulses to superior oblique muscle to move eyeball
Cranial Nerve V: Trigeminal
*Mixed
*Functions
~ Sensory impulses from scalp, face and mouth for touch, pain, temperature, and proprioception
~ Somatic motor impulses to muscles of chewing and middle ear muscles
*Three branches
~ Opthalmic: through superior orbital fissure (Sensory);
Cranial Nerve VI: Abducens
*Motor
~ Some axons for proprioception associated with eyeball muscles
*Functions in movement of eye
~ Carries somatic motor impulses to lateral rectus muscle to move eyeball laterally
- Abducting the eye
Cranial Nerve VII: Facial
*Mixed
*Functions
~ Sensory impulses for taste from taste buds of anterior tongue to primary gustatory area of cerebral parietal lobe
~ Sensory impulses for touch, pain, and temperature fro ear canal
~ Sensory impulses for proprioception from face and sca
Cranial Nerve VIII: Vestibulocochlear
*Sensory
*Functions in sense of hearing and equilibrium
-Vestibular branch (balance)
~ Carries impulses for equilibrium from semicircular canals and vestibule of inner ear to cerebellum
-Cochlear branch (hearing)
~ Carries impulses for hearing from spiral
Cranial Nerve IX: Glossopharyngeal
*Mixed
*Functions
~ Sensory impulses for taste from posterior tongue
~ Sensory impulses for touch, pain, and temperature from external ear and upper pharynx
~ Sensory impulses for proprioception from muscles of swallowing
~ Sensory impulses from barorecep
Cranial Nerve X: Vagus
*Mixed
*Functions
~ Sensory impulses for taste from epiglottis and pharynx
~ Sensory impulses for touch, pain, and temperature for external ear
~ Sensory impulses for proprioception from muscles of neck and throat
~ Sensory impulses from baroreceptors and
Cranial Nerve XI: Accessory
*Motor
~ Some axons for proprioception associated with neck muscles
*Functions in movement of head
~ Carries somatic motor impulses to sternocleidomastoid and trapezius muscles to coordinate head and pectoral girdle movements
~ Considered cranial nerve be
Cranial Nerve XII: Hypoglossal
*Motor
~ Some axons for proprioception associated with tongue muscles (below the tongue)
*Functions in movement of tongue
~ Carries somatic motor impulses to tongue muscles for speech, manipulation of food, and swallowing
What are spinal nerves? How are they named?
*Thirty-one pairs named and numbered by region and level of spinal cord
Where do spinal nerves originate?
*Most pass through intervertebral foramen between vertebrae
*Those below end of spinal cord pass through vertebral foramen before emerging
*Regions
~ Cervical nerves (8)
~ Thoracic nerves (12)
~ Lumbar nerves (5)
~ Sacral nerves (5)
~ Coccygeal nerves (1)