Autonomic Nervous System

what does the ANS control

automatically controls visceral activity

• cardiac

• smooth muscles

• glandular

3 subdivisions of ANS

1. sympathetic

2. parasympathetic

3. enteric

what does the sympathetic ANS do 

readies body to expend energy 

what does the parasympathetic ANS do 

readies the boy to conserve energy 

what does the enteric ANS do 

regulates gastrointestinal motility 

Sympathetic and Parasympathetic Afferents sensory receptor location 

in the viscera 

types of receptors in sympathetic and parasympathetic afferents 

mechanoreceptors, nociceptors, and chemoreceptors 

movement of afferents in the sympathetic and parasympathetic NS 

travel to and through the CNS in a similair fashion as somatic afferents, but go to the hypothalanus rather than the thalamus 

where do sympathetic and parasympathetic effects originate 

hypothalamus 

1st neuron in sympathetic and parasympathetic efferents movement 

cell body in hypothalamus → axon travels to intermediate gray matter in SC 

2nd neuron in sympathetic and parasympathetic efferents 

preganglionic neuron 

preganglionic neuron

cell body in intermediate gray matter in SC → axon travels out of SC through ventral root

3rd neuron in sympathetic and parasympathetic efferents 

postganglionic neuron 

postganglionic neuron

cell body in autonomic ganglion → axon travels to organ/gland

what is the sympathetic autonomic ganglia close to

SC

what is parasympathetic autonomic ganglia close to 

organs they innervate 

where are preganglionic neurons in the parasympathetic system located 

brain stem and sacral spinal cord

parasympathetic system aka

craniosacral system

purpose of parasympathetic system

rest and digest/ conserve energy

2 primary sources of blood flow to the SC

vertebral arteries and thoracic and abdominal aorta 

how many vertebral arteries are there

2 (right and lef)

what do the vertebral arteries arise from

the subclavian artery

2 branches of vertebral areteries that supply the SC 

anterior and posterior spinal arteries 

what does the anterior spinal artery supply

2/3 of the spinal cord

what do the posterior spinal arteries supply

posterior 1/3 of the spinal cord

necessity for thoracic and abdominal aorta in SC blood flow 

the blood flow from the spinal arteries isnt enough to sustain the entire SC, instead radicular arteries supplement the SC blood supply from the lower cervical levels and down 

hemiplegia 

weakness in one half of the body 

paraplegia

weakness in both legs

quadriplegia

weakness in all limbs

neurologic symtoms are the result of

the spinal cord being damaged, nt any vertebral fractures, though fractures of the vertebra can cause SC damage 

SCI is considdred what type of injury 

upper motor neuron injury 

lower motor neuron 

motor neuron whose cell body lies in the CNS but whose axon innervates muscles

upper motor neuron 

motor neuron that descends from the cortex or brainstem and ends on a lower motor neuron 

strength in UMN lesion 

decreased 

muscle tone in UMN lesion 

increased 

stretch reflexes in  in UMN lesion 

increased 

muscle atrophy in in UMN lesion 

midle

other signs in UMN lesion 

clonus and pathological reflexes

strength in LMN lesion 

decreased

muscle tone in LMN lesion 

decreased

stretch reflexes in LMN lesion 

decreased

muscle atrophy in LMN lesion 

severe

other signs in LMN lesion 

fibrilations 

3 ways of classifying SCI

1. level of injury 

2. tetraplegia vs paraplegia

3. complete vs incomplete 

level of injury

categorized by the last level of intact spinal cord, and level of injury can different on r and l sides of the body 

cervical injuries lead to 

quadriplegia 

in general, thoracic, lumbar, and sacral injuries lead to 

paraplegia 

complete SCI injury is characterized by

no sensory or motor function below the level of injury and no anal sensation or contraction 

incomplete SCI is characterized by

some sensory or motor function below neurologic level and anal sensation 

brown-sequard syndrome 

hemisection of spinal cord 

etiology of brown-sequard syndrome

fracture or dislocation of vertebrae, tumor, missile wound 

motor loss in brown-sequard syndrom

same side, motor loss below level of lesion

sensory loss in brown-sequard syndrom

• ipsilateral loss of tactile and proprioception below injury 

• contralateral loss of pain and temp 

central cord syndrome

central cart of cervical SC is affected

what does central cord syndrome result in

more UE motor dysfunction tan LE; variable sensory dysfunction 

why are UE more affected in Central Cord Syndrome 

fibers for upper extremities are more medial in the SC compared to the more lateral fibers in the LEs 

ALS

progressive degenerative disease in which the corticospinal tracts (UNMs) and anterior horn cells in teh SC degenerate 

what characterizes ALS 

weakness and autonomic nervous system dysfunction 

cranial nerves and brain stem damage

problems with cranial nerves since most of them are located near the brain stem 

sensory and motor deficts in brainstem lesion 

deficits bc the brainstem is a conduit of these fibers 

autonomic disruption in brainstem lesion

bc autonomic system is associated with reticular formation