Peripheral Nervous
System
Cranial Nerves
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Olfactory: Smell
Optic: Eyes
Oculomotor: Eye movement (4 of 6 muscles/pupil control
Trochlear: Eye movement (1 of 6 muscles)
Trigmineal: opthalamic, maxillary, mandibular branch. Sensory info
from head/face and motor control for chewing
Abducens: eye movement (1 of 6 muscles), abducts eyeball
Facial: sensory and motor function of face
Vestibulocochlear: balance and hearing
Glossopharyngeal: tongue and pharynx
Vagus: ear canal, diaphragm, taste receptors, visceral receptors (GI)
Accessory: neck and back
Hypoglossal: voluntary control of tongue
Reflexes
• Reflex arc: the path that a reflex signal takes
• 5 steps:
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Stimulus
Activation (sensory neurons)
Processing
Activation (motor neurons)
Response
• Stretch reflex
• Knee jerk
Reflexes
• Withdrawl Reflex
• Flexor reflex: grab a hot pan to test
• Babinski sign:
• Positive Babinski Reflex: fanning of toes
• Plantar Reflex:
• Negative Babinski Reflex: curling of toes
Sensory Pathways
• Posterior Column Pathway:
• Highly localized touch, pressure, vibration, proprioception
• Spinothalamic Pathway:
• Poorly localized touch, pressure, pain, temp.
• Spinocerebellar Pathway:
• Proprioceptive info
Motor Pathways
• Cortiocpinal pathways
• Skeletal muscles
• Medial and lateral pathways
• Subconscious control of muscle tone, reflexive responses
ANS
• Preganglionic Neurons: ANS motor neurons in CNS, send
preganglionic fibers outside of CNS
• Throacic and lumbar spinal segments synapse w/ ganglia near
spinal cord, make up Symp NS
• Ganglionic Neurons: ANS motor neurons in PNS, innervate
cardiacm uscle, smooth muscle, glands, adipose tissue
• Brain and sacral spinal segments synapse on neurons on terminal
ganglia located near the target organ (visceral tissue),
parasympathetic nervous system
Patterns of ANS
• All preganglionic autonomic fibers are cholinergic
• Postganglionic parasympathetic fibers are cholinergic, but can
be excitatory or inhibitory
• Most postganglionic sympathetic fibers release
norepinephrine (adrenergic)
Sympathetic Nervous System
• Preganglionic neurons located b/w T1 and L2 of spinal cord
• Ganglionic neurons located in ganglia near the vertebral
column
• Adrenal medullae
Sympathetic Chain
• Preganglionic fibers that join together
• Leads to widespread affects on the body
• One organ affected, all become affected
Functions of Sympathetic NS
• Fight or Flight
• Increased alertness
• Preparation for intense physical activity
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Sweat glands activated
Arrector pili stimulated
Reduced circulation to skin
Increased blood to skeletal muscle
Release lipids from adipose
Dialate pupils
Parasympathetic NS
• Preganglionic neurons in brain stem and sacral region of spinal
cord
• Ganglionic neurons in peripheral ganglia within or adjacent to
the target organs
Organization of Parasymp. NS
• Vagus nerve (10) provides ~75% of all outflow and innervation
of organs
• Preganglionic fibers from brain travel in cranial nerve 3, 7, 9,
and 10
Functions of Parasymp. NS
• Rest and Digest
• Constrict pupils, increase secretions of GI glands, increase
peristalsis, defecation/urination, constriction of bronchioles,
reduce HR/BP
Activity
• Draw a picture of the brain and spinal cord. Show how the
sympathetic nervous system has a widespread response and
the parasympathetic nervous system has a targeted response
• Give the response to each of the following organs for
sympathetic and parasympathetic stimulation: Heart, Eye,
Lungs, Bladder, Intestines