Peripheral Nervous System ppt – anatomy power point

April 22, 2012 | By | Reply More

Peripheral Nervous System ppt – anatomy power point

Power point presentation

subject – anatomy
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summary
The Peripheral  Nervous System
Peripheral Nervous  System
ways to categorize:Motor or sensory
General (widespread) or specialized (local)
Somatic (outer tube) or visceral (inner tube)____Cranial  nerves attach to brain

___Spinal  nerves attach to spinal  cord

Peripheral sensory  receptors

By location:

Exteroceptors
Sensitive to stimuli arising from outside body
Interoceptors
Or visceroreceptors, from internal viscera
Proprioceptors
Monitor degree of stretch in skeletal muscles, tendons, joints and ligaments

Sensory Receptors

Free nerve endings  (pain and temp)
Merkel discs (light touch)
Root hair plexuses – entwine hair follicles (light touch)
Encapsulated Meissner’s corpuscles (light touch in hairless skin)
Ruffini’s corpusucles (deep pressure and stretch)
Pacinian corpuscles (deep pressure, vibration, visceral: pain, nausea, hunger, fullness)

Proprioceptors

Skeletal muscles,  joints, tendons, ligaments
Degree of stretch, therefore information on body movement:
to cerebrum,
cerebellum and
spinal reflex arcs
Include: -Muscle spindles

-Golgi tendon organs

-Joint kinesthetic receptors

Proprioceptors continued

Muscle spindles:

Intrafusal  fibers – rate & degree of stretch

Golgi tendon organs

Near muscle-tendon  junction: monitor tension within tendons

Joint kinesthetic receptors

Monitor  stretch in  synovial joints

Send  info to cerebellum  and spinal reflex arcs

Peripheral motor  endings

Innervation of skeletal  muscle

Innervation of visceral  muscles and glands

Motor axons innervate  skeletal muscle fibers at neuromuscular junctions  = motor end plates

Resemble nerve synapses  between neurons, except for acetylcholinesterase:

breaks  down acetylcholine so one twitch only

Motor  unit: motor neuron & all the muscle fibers it innervates

All muscles in motor  unit contract together when neuron fires

Stimulation of single  motor unit causes weak contraction of  entire muscle (spread out)

Those with fine control  – fewer fibers per motor neuron (avg.  150: range is 4-100s)

Innervation of  visceral muscles & glands

Near end organ  visceral motor axon swells = presynaptic  terminals (vesicles with neurotransmitters): action  slow (NT diffuses)

Cranial Nerves

Find  as many as you  can on model and  sheep brain

Review of foramina

FYI: many cranial nerves  have their nuclei in the brain stem  (that’s why you’ll see that many attach  to the brainstem)

Cranial nerves

12 pairs, Roman  numerals I-XII
Serve mainly head and neck
Vagus – into thoracic and abdominal cavities
All but first 2 arise from brain stem and pass through foramina in base of skull
Most are mixed (motor and sensory)
3 are purely sensory:
Optic
Olfactory
Vestibulocochlear

Cranial Nerves

All  three divisions: facial  sensation

V3  (mandibular division): chewing  also

V1:  superior orbital fissure

V2:  foramen rotundum

V3:  foramen ovale

Pons  (brainstem)

Trigeminal

V1  ophthalmic

V2  maxillary

V3  mandibular

V

Motor  to superior oblique  muscle of eye (down  & out)

Superior  orbital fissure

Midbrain  (brainstem)

Trochlear

IV

Motor  to 4 of the 6  muscles of eye movement  (up & in); eyelid;   constriction of pupil

Superior  orbital fissure

Midbrain  (brainstem)

Oculomotor

III

Sense  of vision (sight) from  retina

Optic  canal

Forebrain

Optic

II

Sense  of smell

Cribriform  plate

Forebrain

Olfactory

I

Function

Foramen

Attached  to

Name

CN  #

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