Peripheral Nervous System
College: First year
What are the main divisions of the PNS?
-sensory receptors
-afferent nerves
-efferent nerves
-motor endings
What are the 2 types of sensory receptor?
-Somatic sensory receptors
-Visceral sensory receptors
What are somatic sensory receptors for?
-touch, pain, vibration, temp, limb motion, hearing, vision, smell
What are the visceral sensory receptors for?
-stretch, pain, temp, chemical changes
What is the structure of a nerve?
-endoneurium
-perineurium
-epinuerium
Describe endoneurium:
-bundles of individual fibers
-located around Schwann cells and myelin sheath
Describe perineurium:
-bundles fibers into fasicles
Describe epineurium:
-bundles fascicles into a nerve
How many cranial nerves are there?
-there are 12 cranial nerves
I Olfactory Nerve
-Sensory: Smell
II Optic Nerve
-Sensory: Vision(light)
III Oculomotor Nerve
-Motor: Eye Movements
IV Trochlear Nerve
-Motor: Eye Movements
V Trigeminal Nerve
-Sensory: Face(skin & mucose of nose & mouth)
-Motor: Chewing
VI Abducens Nerve
-Motor: Eye Movements
VII Facial Nerve
-Sensory:Taste
-Motor:Face(Tears, expression & salivary glands)
VIII Vestibulocochlear Nerve
-Sensory: Hearing, Balance
IX Glossopharyngeal Nerve
-Sensory:Taste
-Motor: Pharynx(swallowing) & salivary glands
X Vagus Nerve
-Mixed: from pons to pharynx, larynx, and abdominal and thoracic viscera
XI Accessory Nerve
-Motor: Neck & Upper Back
XII Hypoglossal Nerve
-Motor: Tongue
How many pairs of spinal nerves are there?
-31 pairs exiting through the intervertebral foramen
What is the function of the dorsal rami?
-serve the skin nd muslces of the posterior trunk
What is the function of the ventral rami?
-forms a complex of networks(plexus) for anterior
What are some infections that affect the spinal nerves?
-Herpes
-Poliomyelitis
-Anesthetic leprosy
Explain Herpes Virus:
-virus can stay dormant in sesnroy ganglia & erupt later in life
-Shingles in adult from childhood chicken pox
Explain Poliomyelitis:
-virus causes degeneration of the motor neurons in the ventral horn of the spinal cord.
-spread through contaminated water.
Explain Anesthetic leprosy:
-bacteria invades sensory neurons & person cannot detect tissue damage & continues to use damaged area resulting in infection, ulceration, gangrene, or amputation
What are the 2 motor divisions?
-Somatic Nerves
-ANS
Describe Somatic Nerves:
-effectors
-motor endings at the nueromuscular junction concentrate NT
What are the 2 pathways of the Autonomic Nervous System?
-Parasympathetic Nerves
-Sympathetic Nerves
Describe ANS:
-(involuntary) to internal organs has two pathways
Describe Parasympatheric Nerves:
-routine daily activities with the ability to relax& slow down organ function
Describe Sympathetic Nerves:
-vigorous exercise, excitement, emergency response
What are a few examples of reflexes?
-stretch reflex
-withdrawal reflex
-cross extensor reflex
What is the function of stretch reflex?
-muscle spindle receptors send action potentials in response to fibers stretching(EX:Knee Jerk)
What is the function of withdrawal reflex?
-Removing body parts from painful stimulus(EX:Arm Withdrawal from touching stove)
What is the function of cross extensor reflex?
-One part of the body withdrawals while the opposite side of the body extends