autonomic nervous system presentation

Ch. 7 – The Nervous System

• Overview & Organization of the Nervous System

Functions of the Nervous System

The master controlling & communicating system of the body…

• Sensory input —gathering information
• To monitor changes occurring inside and outside the body
• Changes = stimuli
• Integration
• To process and interpret sensory input and decide if action is needed
• Motor output
• A response to integrated stimuli
• The response activates muscles or glands
• Structural Classification �of the Nervous System
• Central nervous system (CNS) – dorsal body cavity; integrating and command centers; interpret sensory information & give out instructions

Spinal cord

• Peripheral nervous system (PNS) – outside of CNS
• Nerves outside the brain and spinal cord
• Spinal nerves – carry impulses to and from spinal cord
• Cranial nerves – carry impulses to and from brain
• Functional Classification of �the Peripheral Nervous System
• Sensory (afferent) division
• Nerve fibers that carry information to the CNS
• Somatic sensory fibers – deliver impulses from skin, skeletal muscle, and joints
• Visceral sensory fibers (afferents) – deliver impulses from viscera
• Motor (efferent) division
• Nerve fibers that carry impulses away from the CNS
• Somatic (voluntary) NS – voluntary control of skeletal muscles
• Autonomic (involuntary NS – involuntary control of smooth & cardiac muscle and glands
• Divided into sympathetic and parasympathetic NS

Answer Did You Get It? #1

• Structure & Function of Nervous Tissue
• Support Cells
• Support cells in the CNS are grouped together as neuroglia (AKA glia or glial cells ) = “nerve glue”
• Functions: support, insulate, and protect neurons
• Cannot transmit nerve impulses (as can neurons)
• Never lose their ability to divide (as neurons do)
• Most brain tumors are gliomas
• Glia of the Central Nervous System:
• Ependymal cells
• Oligodendrocytes
• Glia of the Peripheral Nervous System:
• Schwann cells
• Satellite cells

Support Cells, continued…

• Abundant (~1/2 of neural tissue)
• Star-shaped cells
• Brace & anchor neurons to capillaries
• Form living barrier between capillaries and neurons (exchange) (blood-brain barrier)
• Control brain’s chemical environment
• Absorb leaked K + ions
• Absorb released neurotransmitters
• Spiderlike phagocytes
• Protect from infection
• Dispose of debris
• Dead brain cells & bacteria
• Line cavities of the brain and spinal cord
• Beating cilia circulate cerebrospinal fluid (CSF)
• CSF fills brain & spinal cord cavities & serves as cushion
• Wrap around nerve fibers in the CNS
• Produce fatty insulating coverings = myelin sheaths
• Protect neuron cell bodies
• Form myelin sheath around nerve fibers in the PNS

Answer Did You Get It? #’s 2-3

• Neurons = nerve cells
• Cells specialized to transmit nerve impulses from one part of body to another
• Two major regions of neurons:
• Metabolic center: contains nucleus, large nucleolus
• No centrioles = no mitosis
• Nissl substance = specialized RER
• Neurofibrils (intermediate cytoskeleton)
• Maintain cell shape

Neurons, continued…

• Processes outside the cell body
• Microscopic to 3-4 ft in length
• Longest = from lumbar region of spine to great toe
• Dendrites —conduct impulses toward the cell body
• A neuron may have hundreds
• Axons —conduct impulses away from the cell body
• Arises from cone-like region of cell body called axon hillock
• Collateral branches
• End in highly branched axon terminals
• Axon terminals contain vesicles with neurotransmitters
• Axonal terminals are separated from the next neuron by a synaptic cleft
• Synapse —junction between nerves ( syn = clasp/join)

Neuron processes, continued…

• Myelin sheath —whitish, fatty material covering axons
• Protects & insulates fibers
• Increases rate of nerve impulse transmission
• Schwann cells —produce myelin sheaths in jelly roll–like fashion
• Schwann cells in the PNS; oligodendrocytes in the CNS
• Neurilemma – portion of cell membrane on outer layer of coil where most of its cytoplasm resides
• Nodes of Ranvier —gaps in myelin sheath along the axon
• Aid in speeding up nerve impulses – saltatory conduction
• Homeostatic imbalance – multiple sclerosis = gradual destruction of myelin sheaths (become hardened = sclerosis), autoimmune disease (sheath protein)
• Visual & speech disturbances, loss of muscle control, increasingly disabled
• Interferon injections provide relief; no cure
• Terminology of Neurons
• Most neuron cell bodies are found in the CNS
• Nuclei —clusters of cell bodies within the white matter of the CNS (protected within the brain case and vertebral column)
• Ganglia —small collections of cell bodies in the PNS
• Tracts = bundles of nerve fibers in CNS
• White matter – myelinated tracts in CNS
• Gray matter —cell bodies and unmyelinated tracts in CNS
• Nerves = bundles of nerve fibers in PNS
• Functional Classification of Neurons

Direction of nerve impulse with respect to CNS

• Sensory (afferent) neurons
• Carry impulses from the sensory receptors to the CNS
• Ganglion outside of CNS
• Dendrite endings associate with receptors
• Cutaneous sense organs in muscles and tendons
• Proprioceptors —detect stretch or tension

Naked nerve ending; pain/temp

Meissner’s corpuscule: touch

Pacinian corpuscule: deep pressure

Golgi tendon organ & muscle spindle;: proprioception

Functional Classification of Neurons, continued…

• Motor (efferent) neurons
• Carry impulses from the central nervous system to viscera, muscles, or glands
• Cell bodies always in CNS
• Interneurons (association neurons)
• Connect sensory and motor neurons in neural pathways
• Structural Classification of Neurons
• Multipolar neurons—many extensions from the cell body
• most common
• Bipolar neurons—one axon and one dendrite
• Rare in adults
• Act in sensory processing – eye, nose
• Unipolar neurons—have a short single process leaving the cell body
• Divides into proximal (central) and distal (peripheral) processes
• Dendrites only at peripheral end
• Conducts action potentials both ways
• Found in sensory neurons of PNS ganglia

Answer Did You Get It? #’s 4-7

• Physiology of the Nervous System
• Functional Properties of Neurons
• Irritability - ability to respond to stimuli and convert to nerve impulses
• Conductivity - ability to transmit an impulse to other neurons, muscles, or glands
• Nerve Impulses
• Electrical conditions of a resting neuron’s membrane
• Polarized – resting/inactive neuron
• Fewer positive ions on inner face of plasma membrane than on outer face
• Depolarized – stimulated neuron
• More positive ions inside the cell than outside

Nerve Impulses, continued…

• Action Potential Initiation and Generation
• Stimuli excite neurons: light, sound, pressure, mostly neurotransmitters released by other neurons
• Cause a temporary change in the cell membrane’s permeability
• Stimulus causes sodium channel gates to open, and sodium to rush in
• Causes depolarization of the neuron’s membrane
• Inside more positive, outside less positive = graded/local potential
• If stimulus is strong enough, a long distance signal called an action potential or nerve impulse occurs
• Nerve impulses are all-or-nothing responses – they are either propagated over the entire axon or not at all
• Repolarization
• Membrane immediately becomes impermeable to sodium, but permeable to potassium ions
• K + ions rush out of the neuron, restoring electrical conditions to polarized = repolarization
• Repolarization must occur before another impulse can be conducted
• The sodium-potassium pump, using ATP, restores the original concentrations of Na + and K + .
• Saltatory conduction = In myelinated fibers, propagation occurs more quickly since the nerve impulse jumps from node to node.
• Homeostatic imbalance: factors that impair impulse conduction:
• Sedatives & anesthetics block sodium entry
• Cold & continuous pressure interrupt blood circulation (nutrients & O 2 ) – e.g. ice creates numbness, foot “goes to sleep”; prickly feeling caused by impulse transmission starting back up
• Transmission of the Signal at Synapses
• Neurotransmitter is released from vesicles within the axon terminal
• Neurotransmitter molecules diffuse across the synapse
• Neurotransmitters bind to receptors in the membrane of the next neuron
• If enough neurotransmitters are released, another nerve impulse will be generated in this neuron
• Enzymes remove the neurotransmitters from the receptors
• Impulse transmission is an electrochemical event – electrical along the neuron’s membrane; chemical within the synapses

Axon�terminal

Synaptic�cleft

Action�potential�arrives

Axon of�transmitting�neuron

Receiving�neuron

Neurotrans-�mitter is re-�leased into�synaptic cleft

Neurotrans-�mitter binds�to receptor�on receiving�neuron’s�membrane

Vesicle�fuses with�plasma�membrane

Synaptic cleft

Neurotransmitter�molecules

Ion channels

Receiving neuron

Transmitting neuron

Neurotransmitter

Neurotransmitter�broken down�and released

Ion channel opens

Ion channel closes

• Reflex — rapid, predictable, and involuntary response to a stimulus
• Always travel in one direction
• Occurs over pathways called reflex arcs
• Reflex arc — direct route from a sensory neuron, to an interneuron, to an effector
• Neural pathway involving the CNS and PNS

Stimulus at distal�end of neuron

(in cross section)

Interneuron

Sensory neuron

Motor neuron

Integration�center

Reflexes, continued…

• Types of Reflexes
• Somatic reflexes
• Reflexes which stimulate the skeletal muscles
• Example: moving hand away from a hot stove
• Autonomic reflexes
• Regulate the activity of smooth muscles, heart, and glands
• Examples: salivary reflex, pupillary reflex
• Regulate: digestion, elimination, blood pressure, and sweating
• Parts of a reflex arc
• Sensory receptor – reacts to a stimulus
• Integration center
• Effector organ – muscle or gland which is stimulated
• Patellar (knee-jerk) reflex is an example of a two-neuron reflex arc

Figure 7.11d

Figure 7.11b–c

Sensory (afferent)�neuron

Motor�(efferent)�neuron

Sensory receptors�(stretch receptors�in the quadriceps�muscle)

Effector�(quadriceps�muscle of�thigh)

Synapse in�ventral horn�gray matter

Inter-�neuron

Sensory receptors�(pain receptors in�the skin)

Effector�(biceps�brachii�muscle)

• Flexor (withdrawal) reflex is an example of a three-neuron reflex arc
• Withdrawal reflex arc has an interneuron
• The more neurons involved, the slower the communication because of the time it takes for neurotransmitters to diffuse
• Many spinal reflexes do not involve the brain
• Other reflexes require the brain to evaluate different types of information
• Reflex testing evaluates condition of the nervous system
• Exaggerated, distorted, and absent reflexes indicate nervous system disorders

Answer Did You Get It? #’s 8-11

• Central Nervous System (CNS)
• CNS develops from the embryonic neural tube
• Runs along the dorsal median plane
• 4 th week – anterior end expands = brain formation
• Rest of tube = spinal cord
• The central canal of the neural tube enlarges into 4 chambers = ventricles
• Filled with cerebrospinal fluid
• Functional Anatomy of the Brain
• ~3 lbs, wrinkled, texture similar to cold oatmeal
• 4 major regions:
• Cerebral hemispheres (cerebrum)
• Diencephalon

Regions of the Brain: Cerebrum

• Cerebrum (cerebral hemispheres)
• Paired, superior parts of the brain
• Includes more than half of the brain mass; obscures most of the brain stem
• The surface is made of ridges ( gyri = “twisters”) and grooves ( sulci = “furrows”)
• Fissures (deep grooves) divide the cerebrum into lobes
• Occipital lobe
• Temporal lobe

Figure 7.13b

• Cerebral Cortex
• Functions : speech, memory, logic, emotion, consciousness, sensation interpretation, & voluntary movement
• Cell bodies of neurons in cerebral cortex in outermost gray matter
• Primary somatic sensory area
• In parietal lobe posterior to central sulcus
• Receives & interprets impulses from the body’s sensory receptors
• Detects: pain, cold, light touch

Sensory & motor homunculus – the more neurons there are for a function, the larger the area represented by that body region

Figure 7.14

• Visual area in occipital lobe
• Auditory area in temporal lobe
• Olfactory area deep in temporal lobe
• Primary motor area in frontal lobe
• Conscious movement of skeletal muscle
• Axons of these motor neurons form the corticospinal or pyramidal tract
• Descends to spinal cord
• Broca’s area at base of precentral gyrus
• Involved in our ability to speak
• Only located in one (usually left) hemisphere
• Damage here can cause inability to speak – conscious of what you want to say, but unable to do it
• Frontal association areas – higher intellectual reasoning & socially acceptable behavior
• Complex memories stored in temporal and frontal lobes
• Speech/language (Wernicke’s) area – junction of temporal, parietal, & occipital lobes
• Allows us to sound out words
• Usually in just one hemisphere
• Damage: Wernicke’s aphasia – lack of language comprehension; clear speaking though
• Frontal lobes – language comprehension (word meaning)
• Gustatory area – taste – base of primary somatic sensory area (parietal)
• General interpretation area – temporal & parietal
• Cerebral White Matter
• White matter—fiber tracts carrying impulses to, from, and within the cortex
• Corpus callosum – large tract connecting hemispheres; allows hemispheres to communicate with one another
• Called commisures
• Association fiber tracts connect areas within hemispheres ; projection fiber tracts connect cerebrum to lower CNS centers
• Basal nuclei (basal ganglia ) — islands of gray matter buried within the white matter
• Regulate voluntary

motor activities

• Homeostatic Imbalance:
• Problems with basal

nuclei cause difficulty in

walking or other voluntary

movements: Huntington’s

disease & Parkinson’s

Answer Did You Get It? #’s 12-13

• Regions of the Brain: Diencephalon (Interbrain)
• Sits on top of brain stem; enclosed by the cerebral hemispheres
• Made of three parts: Thalamus, Hypothalamus, Epithalamus
• Thalamus – relay station for sensory impulses traveling up to sensory cortex
• Crude awareness of a pending sensation being pleasant or not
• Hypothalamus – floor of diencephalon
• Autonomic NS center: helps body temp, water balance, & metabolism
• Limbic system – “emotional-visceral brain” where thirst, appetite, sex, pain, and pleasure centers are
• Regulates the pituitary gland ; secretes hormones
• Mammillary bodies – reflex centers involved in olfaction

Regions of the Brain: Diencephalon

• Epithalamus
• Forms the roof of the third ventricle
• Houses the pineal body (an endocrine gland)
• Includes the choroid plexus —complex of capillaries which form cerebrospinal fluid

Regions of the Brain: Brain Stem

• Small: ~thumb in diameter & ~3” long
• 3 regions: midbrain, pons, & medulla oblongata
• Provides a pathway for ascending & descending tracts
• Contains nuclei with rigidly programmed autonomic behaviors necessary for survival
• Some connected to cranial nerves controlling breathing & blood pressure
• From mammilary bodies to pons
• Cerebral aqueduct – canal connecting 3 rd ventricle of diencephalon to 4 th ventricle
• Has two bulging fiber tracts — cerebral peduncles : convey ascending & descending impulses
• Mostly composed of tracts of nerve fibers
• Has four rounded protrusions— corpora quadrigemina (“gemini” = twins)
• Reflex centers for vision and hearing
• Pons (“bridge”)
• Rounded part of brain stem just below midbrain
• Mostly composed of fiber tracts
• Includes nuclei involved in the control of breathing
• Medulla Oblongata
• Most inferior part of the brain stem
• Merges into the spinal cord
• Includes important fiber tracts
• Contains nuclei which control:
• Blood pressure
• Fourth ventricle
• Reticular Formation
• Diffuse mass of gray matter along the length of the brain stem
• Involved in motor control of visceral organs
• Reticular activating system (RAS) plays a role in awake/sleep cycles and consciousness
• Damage here can cause a coma (permanent unconsciousness)
• Regions of the Brain: Cerebellum
• Cauliflower-like, dorsally projecting from under the occipital lobe
• Two hemispheres with convoluted surfaces
• Outer cortex composed of gray matter; inner region composed of white matter
• Provides precise timing for skeletal muscle activity and controls balance & equilibrium
• “Automatic pilot” – compares brain’s intentions with body’s actual performance; initiates appropriate corrective measures
• Ataxia – damage to cerebellum can result in clumsy & disorganized movements; appear to be drunk

Answer Did You Get It? #’s 14-16

• Protection of the Central Nervous System
• Nervous tissue is soft and delicate; neurons injured easily
• Brain and spinal cord protected by
• Scalp and skin
• Skull and vertebral column
• Meninges (membranes)
• Cerebrospinal fluid (watery cushion)
• Blood-brain barrier – protection from harmful substances in the blood

Figure 7.17b

• Connective tissue membranes which cover & protect the CNS
• Double-layered, outermost layer; leathery
• Periosteal layer (periosteum)—attached to inner surface of the skull
• Meningeal layer —outer covering of the brain; fuses with the dura mater of the spinal cord
• Layers are fused except in dural venous sinuses where venous blood is collected
• Inward folds attach brain to cranial cavity
• Falx cerebri & tantorium cerebelli
• Arachnoid mater (“spider”)
• Middle layer
• Attached to the pia mater, forming the subarachnoid space
• Filled with cerebrospinal fluid (CSF)
• Arachnoid villi – projections of arachnoid mater; protrude through dura mater
• CSF passes into dural sinuses through these structures
• Pia mater (“gentle mother”)
• Innermost membrane
• Clings tightly brain and spinal cord surfaces
• Epidural injections – “upon the dura”
• Homeostatic Imbalance :
• Meningitis – inflammation of the meninges
• Bacterial or vial infections
• Serious threat to brain if spreads into CNS
• Encephalitis – inflammation of the brain
• Diagnosed by sampling CSF

Cerebrospinal Fluid (CSF)

• Similar to blood plasma composition
• Less protein, more vitamin C, different ion composition
• Formed from blood by choroid plexuses
• Clusters of capillaries hanging from each of brain’s ventricles
• Forms a watery cushion to protect the brain from trauma
• Circulated in arachnoid space, ventricles, and central canal of the spinal cord
• CSF continually circulates in brain
• From two lateral ventricles, to 3 rd ventricle, through cerebral aqueduct, to 4 th ventricle
• Some CSF continues to spinal cord
• Normally circulates at a constant rate
• Changes to CSF composition may indicate meningitis, tumors, or MS
• Lumbar/spinal tap – sample the CSF
• Remain lying down for 12 hrs or “spinal headache”
• Homeostatic Imbalance - Hydrocephalus
• If something obstructs CSF drainage, it accumulates and exerts pressure on the brain
• “Water on the brain”
• Results in enlarged head in newborns with increasing brain size
• Would cause brain damage in adults
• Treated by surgically inserting a shunt (plastic drain); drains excess fluid into a vein
• Blood-Brain Barrier
• Brain is super sensitive to having a constant internal environment
• Neurons kept separated from bloodborne substances by the blood-brain barrier
• Composed of least permeable capillaries of the body
• Bound by tight junctions
• Allowed to enter:
• Water, glucose, and essential amino acids pass easily through
• Metabolic wastes (urea, toxins, proteins, most drugs), nonessential amino acids, K +
• Useless as a barrier against some substances
• Fats and fat soluble molecules
• Respiratory gases

Answer Did You Get It? #’s 17-19

• Traumatic Brain Injuries
• Head injuries are leading cause of accidental death in US; caused by damaging blow to head
• Further damage caused by brain ricocheting on opposite end of skull
• Slight brain injury
• Dizzy/”see stars,” briefly lose consciousness
• No permanent brain damage
• Marked tissue destruction occurs
• May remain conscious if cerebral cortex injury; may be in coma if brain stem is injured severely (especially RAS)
• Nervous tissue does not regenerate
• Intracranial hemorrhage
• Bleeding from ruptured vessels
• May cause death
• Cerebral edema
• Brain swelling from the inflammatory response
• May compress and kill brain tissue – neurological deterioration
• Cerebrovascular Accident (CVA/Stroke)
• 3 rd leading cause of death in US
• Blood circulation to brain is obstructed by a blood clot or ruptured blood vessel
• Brain tissue supplied with oxygen from that blood source dies
• Loss of some functions or death may result; undamaged neurons can spread into damaged areas and take over some lost functions (= neuroplasticity )
• Hemiplegia – one-sided paralysis ( e.g. right-sided paralysis = damage to left motor cortex)
• Apahsia – damage to language areas
• Motor/Broca’s aphasia – loss of ability to speak
• Sensory/Wernicke’s aphasia – loss of ability to understand written & spoken language
• Transient ischemic attack (ITA) – temporary restriction of blood flow (ischemia) to brain
• Last 5-50 min; numbness, temporary paralysis; impaired speech
• Warning of impending, more serious CVA

Answer Did You Get It #20

• The Terrible Three
• Alzheimer’s Disease
• Progressive degenerative brain disease, results in dementia (mental deterioration)
• Mostly seen in the elderly, but may begin in middle age
• Victims experience: memory loss, short attention span, disorientation, eventual loss of language, irritability, moodiness, confusion, sometimes violent, and ultimately, hallucinations.
• Structural changes in the brain include: low Ach, shrinking gyri, brain atrophy (especially in areas of thought and memory), abnormal protein (senile plaque – beta amyloid peptide ) deposits, and twisted tau fibers within neurons
• Treat with acetylcholinesterase inhibitors
• Parkinson’s Disease
• Problem associated with basal nuclei; cause not known
• Typically affects people in 50’s-60’s
• Degeneration of dopamine-releasing neurons in the substantia nigra, causing basal nuclei to become overactive
• Symptoms: persistent tremor (even at rest), head nodding, “pill-rolling” of fingers, forward-bent walking posture, shuffling gait, stiff facial expressions, difficulty in initiating movements
• Treatments: L-dopa for some symptoms (bad side effects); deprenyl to slow degeneration; thalamic stimulation via electrodes alleviates tremors; implants of embryonic tissue promising
• Huntington’s Disease
• Genetic disorder (dominant) – typically occurs at middle-age
• Massive degeneration of basal nuclei and later of the cerebral cortex
• Progressive symptoms: wild, jerky movements ( chorea ), later marked mental deterioration
• Typically fatal within 15 years
• Overstimulation of motor cortex
• Treat with drugs that block dopamine; fetal tissue implants are promising
• Spinal Cord
• 2-way conduction pathway to and from the brain
• Major reflex center (spinal reflexes)
• Extends from the foramen magnum of the skull to the first or second lumbar vertebra
• Cushioned & protected by meninges
• 31 pairs of spinal nerves arise from the spinal cord
• Cervical & lumbar enlargements – origin of upper & lower limb nerves
• Cauda equina (horse’s tail) is a collection of spinal nerves at the inferior end

Spinal Cord Anatomy

• Gray matter of Spinal Cord and Spinal Roots
• Gray matter surrounds the central canal (filled with CSF)
• Dorsal (posterior) horns – project posteriorly
• Contain interneurons
• Sensory neuron cell bodies in dorsal root ganglia ; enter spinal cord through dorsal root
• Anterior (ventral) horns – project anteriorly
• Motor neuron cell bodies in ventral horns; axons exit spinal cord through ventral root
• Homoeostatic imbalance – flaccid paralysis – damage to ventral root = no stimulation of muscles
• Spinal nerves – fusion of dorsal and ventral roots
• White matter of the Spinal Cord
• Myelinated fiber tracts (see 7.22)
• Dorsal, lateral, ventral columns
• Sensory/afferent tracts – conduct sensory impulses to brain
• Motor/efferent tracts – conduct impulses from brain to skeletal muscles
• Dorsal column tracts are all ascending carrying sensory input to brain
• Lateral & ventral tracts contain both ascending & descending tracts
• Homeostatic imbalance – spastic paralysis : transected (cut crosswise) or crushed spinal cord – affected muscles stay healthy b/c still stimulated, but moments become spastic; loss of feeling below injury
• Quadriplegic = 4 limbs affected
• Paraplegic = legs only

Answer Did You Get It? #’s 21-23

• Peripheral Nervous System (PNS)
• Nerves and ganglia outside CNS
• Structure of a Nerve
• Nerve = bundle of neuron fibers outside the CNS
• Neuron fibers are bundled by connective tissue
• Delicate endoneurium surrounds each fiber
• Groups of fibers are bound into fascicles by coarser perineurium
• Fascicles are bound together by tough, fibrous epineurium
• Forms cordlike nerve

Structure of a Nerve, continued…

• Nerves are classified according to the direction in which they transmit impulses:
• Mixed nerves – nerves with both sensory and motor fibers
• Sensory (afferent) nerves – nerves carrying impulses toward the CNS
• Motor (efferent) nerves – nerves carrying impulses away from the CNS
• Cranial Nerves
• 12 pairs of nerves that mostly serve the head and neck
• Only the pair of vagus nerves extend to thoracic and abdominal cavities
• Numbered in order; names typically match the structures they control
• Most are mixed nerves, but three are sensory only (optic, olfactory, & vestibulocochlear)

Cranial Nerves, continued…

• Olfactory nerve — sensory for smell
• Optic nerve — sensory for vision
• Oculomotor nerve — motor fibers to eye muscles (most movements, lens shape, & pupil size)
• Trochlear nerve — motor fiber to eye muscle (superior oblique)
• Trigeminal nerve — sensory for the face, nose, & mouth; motor fibers to chewing muscles
• Abducens nerve — motor fibers to eye muscles (lateral movement)
• Facial nerve — sensory for anterior taste buds; motor fibers for facial expression and lacrimal & salivary glands
• Vestibulocochlear nerve — sensory for balance and hearing
• Glossopharyngeal nerve — sensory for posterior taste buds; motor fibers to the pharynx (swallowing & saliva production); carotid artery pressure sensors
• Vagus nerves — sensory and motor fibers for pharynx, larynx, and thoracic & abdominal viscera (mostly parasympathetic = promote digestion & regulate heart activity)
• Accessory nerve — motor fibers to sternocleidomastoid & trapezius
• Hypoglossal nerve — motor fibers for tongue movements; sensory impulses from tongue
• O h O nce O ne T akes T he A natomy F inal V ery G ood V acations A re H eavenly.
• O nly O wls O bserve T hem T raveling A nd F inding V oldemort G uarding V ery S ecret H orcruxes
• Spinal Nerves & Nerve Plexuses
• There are 31 pairs formed by the combination of the ventral and dorsal roots of the spinal cord
• Named for the region from which they arise
• Spinal nerves divide after leaving the spinal cord
• Dorsal rami — serve the skin and muscles of the posterior trunk
• Ventral rami — for nerves T 1 -T 12 forms intercostal nerves (muscles between ribs & skin and muscles of anterior trunk); for rest of nerves forms a nerve networks ( plexus ) for limb sensory & motor

Answer Did You Get It? #’s 24-27

Spinal Nerves & Nerve Plexuses, continued…

• Cervical plexus – from C 1 –C 5 ventral rami
• Phrenic nerve – diaphragm; shoulder/neck muscles
• Brachial plexus – from C 5 –C 8 and T 1 ventral rami
• Axillary nerve – deltoid muscle, shoulder skin; superior thorax muscles & skin
• Radial nerve – triceps & extensor muscles; upper limb posterior skin
• Median nerve – flexor muscles; forearm skin; some hand muscles
• Musculocutaneous nerve – arm flexor muscles; lateral forearm skin
• Ulnar nerve – some forearm flexor muscles; wrist & hand muscles; hand skin
• Lumbar plexus – from L 1 –L 4 ventral rami
• Femoral nerve – lower abdomen , hip flexors & knee extensors; leg & thigh anteromedial skin
• Obturator nerve – adductor & small hip muscles; medial thigh & hip joint skin
• Sacral plexus – from L 4 –L 5 and S 1 –S 4 ventral rami
• Sciatic nerve – largest nerve in body; splits into two nerves; lower trunk & posterior thigh surface (hip extensors & knee flexors)
• Common fibular nerve – lateral leg & foot
• Tibial nerve – posterior leg & foot
• Superior & inferior gluteal nerves – gluteal muscles

Distribution of Major Peripheral Nerves of the �Upper and Lower Limbs

Spinal Nerve Plexuses

Autonomic Nervous System (AKA Involuntary NS)

• Motor subdivision of the PNS
• Controls body activities automatically
• Special neurons that regulate cardiac muscle, smooth muscle (visceral organs & blood vessels), and glands
• Helps to maintain homeostasis – constantly makes adjustments to keep internal conditions stable
• Consists only of motor nerves

Note the differences between ANS & SNS

Autonomic Nervous System, continued…

• Somatic vs. Autonomic nervous systems (both PNS)
• Different effector organs and neurotransmitters
• Somatic NS has cell bodies in CNS and an axon that extends to the effector organ
• Autonomic NS has a chain of two motor neurons
• Preganglionic axon – 1 st neuron; in the CNS (“before the ganglion”)
• Postganglionic axon – 2 nd neuron; outside of CNS; goes to organ
• Two divisions of ANS
• Sympathetic & parasympathetic division
• Regulate the same organs, but with opposite effects (counterbalance one another)
• Sympathetic division – mobilizes body during extreme situations (“fight vs. flight”)
• Parasympathetic division – rest and digest; unwind & conserve

Brain & Spinal Cord Cranial & Spinal Nerves

Sensory Division Motor Division

(Periphery → CNS) (CNS → Periphery)

Afferent/Incoming Efferent/Outgoing

Cranial Spinal Somatic Motor NS Autonomic NS

Nerves Nerves Voluntary Involuntary

Sympathetic Parasympathetic Enteric

Stimulatory Inhibitory GI

• Anatomy of the Parasympathetic Division
• Originates from brain nuclei of cranial nerves (III, VII, IX, & X) and S 2 -S 4
• AKA craniosacral division
• Cranial neurons synapse with ganglionic motor neuron in terminal ganglia (basically are at the effector organs)
• Sacral preganglionic neurons form pelvic splanchnic nerves (pelvic nerves) – pelvic cavity
• Always uses acetylcholine as a neurotransmitter
• Anatomy of the Sympathetic Division
• Originates from gray matter in spinal cord from T 1 through L 2
• AKA thoracolumbar division
• Ganglia are at the sympathetic trunk (near the spinal cord)
• Short pre-ganglionic neuron and long post-ganglionic neuron transmit impulse from CNS to the effector
• Norepinephrine and epinephrine are neurotransmitters to the effector organs
• Sympathetic Functioning —“fight or flight”
• Response to unusual stimulus
• Takes over to increase activities
• Remember as the “E” division
• Exercise, excitement, emergency, and embarrassment
• Homeostatic Imbalance – excessive sympathetic NS stimulation
• Type A personality – never slows down; may be susceptible to heart disease, high blood pressure, ulcers
• Parasympathetic Functioning —“housekeeping” activites
• Conserves energy (rest & digest)
• Maintains daily necessary body functions
• Remember as the “D” division
• digestion, defecation, and diuresis

Answer Did You Get It? #’s 28-30

• Tracking Down CNS Problems
• EEG – electroencephalography
• Recording of brain neuron’s electrical impulse transmission
• Attach electrodes on scalp
• Record speed of brain waves (unique to each individual)
• Alpha = awake, relaxed state
• Beta = awake, alert state
• Theta = common in children, not normal adults
• Delta = deep sleep

Tracking Down CNS Problems, continued…

• CT, MRI & PET scans
• CT (computed axial tomography) & MRI (magnetic resonance imaging) – easily identify tumors, intracranial lesions, MS plaques & areas of dead brain tissue (infarcts)
• PET scans – localize lesions that cause epileptic sezures; used for Alzheimer’s diagnosis, and in cancer tumor activity

CT Scan: normal vs. tumor

PET Scan: normal vs. Alzheimer’s disease

• Cerebral angiography
• Used to visualize arteries in brain
• Used to guide a catheter carrying clot-busting drugs (tPA)

Cerebral angiogram showing an aneurism

87-year-old man with acute onset left hemiplegia. . The image on the left (A) obtained preoperatively. The image on the right (B) was obtained after intra-arterial thrombolysis.

• Development Aspects of the Nervous System
• The nervous system is formed during the first month of embryonic development; therefore, any maternal infection can have extremely harmful effects
• Maternal measles (rubella) = deafness
• Lack of O 2 for minutes can cause neuron death
• Smoking decreases amount of O 2 in blood; less O 2 to developing fetus’s brain (potentially brain damage)
• Radiation & drugs (alcohol, opiates, cocaine, etc.) can all damage fetal nervous system development
• Homeostatic imbalances :
• Cerebral palsy – poor control and spastic movements of voluntary muscles, seizures, mental retardation, impaired hearing & vision
• Can be caused by lack of O 2 during difficult delivery
• Anencephaly – failure of the cerebrum to develop; cannot hear, see, or process sensory inputs
• Spina bifida – “forked spine”; vertebra fail to completely form; can result in varying degrees of paralysis & loss of bowel and bladder control

Development Aspects of the Nervous System, cont’d

• The hypothalamus is one of the last areas of the brain to develop (regulates body temperature_
• Premature babies can’t thermoregulate well
• Continued growth & maturation of nervous system through childhood
• Myelination: cranial to caudal; proximal to distal
• Brain is maximum weight as young adult
• Neurons then continue to get damaged and die
• Steady decline of brain weight and volume
• Can still learn throughout life; unlimited neural pathways available
• Sympathetic NS becomes less efficient (especially in constricting blood vessels)
• Orthostatic hypotension – pooling of blood in the feet due to lack of activation of vasoconstrictor fibers and lightheadness; common in elderly when they stand up quickly
• Arteriosclerosis (plaque build up in arteries) and high blood pressure result in less O 2 supply to brain
• Can causes senility – forgetfulness, irritability, confusion, and difficulty in concentrating and thinking clearly
• Some drugs, low blood pressure, constipation, poor nutrition, depression, dehydration, and hormone imbalances can cause “reversible senility”
• Professional boxers (& other high impact sports) and chronic alcoholics hasten the effects of aging on the brain
• “Punch drunk” – slurred speech, tremors, abnormal gait, dementia in retired boxers
• Reduced brain size in both

Answer Did You Get It? #’s 31-32

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StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.

StatPearls [Internet].

Anatomy, autonomic nervous system.

Joshua A. Waxenbaum ; Vamsi Reddy ; Matthew Varacallo .

Affiliations

Last Update: July 24, 2023 .

• Introduction

The autonomic nervous system is a component of the peripheral nervous system that regulates involuntary physiologic processes including heart rate, blood pressure, respiration, digestion, and sexual arousal. It contains three anatomically distinct divisions: sympathetic, parasympathetic, and enteric.

The sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS) contain both afferent and efferent fibers that provide sensory input and motor output, respectively, to the central nervous system (CNS). Generally, the SNS and PNS motor pathways consist of a two-neuron series: a preganglionic neuron with a cell body in the CNS and a postganglionic neuron with a cell body in the periphery that innervates target tissues. The enteric nervous system (ENS) is an extensive, web-like structure that is capable of function independently of the remainder of the nervous system. [1] [2]  It contains over 100 million neurons of over 15 morphologies, greater than the sum of all other peripheral ganglia, and is chiefly responsible for the regulation of digestive processes. [3] [4]

Activation of the SNS leads to a state of overall elevated activity and attention: the “fight or flight” response. In this process, blood pressure and heart rate increase, glycogenolysis ensues, gastrointestinal peristalsis ceases, etc. [5]  The SNS innervates nearly every living tissue in the body. The PNS promotes the “rest and digest” processes; heart rate and blood pressure lower, gastrointestinal peristalsis/digestion restarts, etc. [5] [6]  The PNS innervates only the head, viscera, and external genitalia, notably vacant in much of the musculoskeletal system and skin, making it significantly smaller than the SNS. [7]  The ENS is composed of reflex pathways that control the digestive functions of muscle contraction/relaxation, secretion/absorption, and blood flow. [3]

Presynaptic neurons of both the SNS and PNS utilize acetylcholine (ACh) as their neurotransmitter. Postsynaptic sympathetic neurons generally produce norepinephrine (NE) as their effector transmitter to act upon target tissues, while postsynaptic parasympathetic neurons use ACh throughout. [1] [5]  Enteric neurons have been known to use several major neurotransmitters such as ACh, nitrous oxide, and serotonin, to name a few. [8]

• Structure and Function

Sympathetic Nervous System

Sympathetic neurons have cell bodies located in the intermediolateral columns, or lateral horns, of the spinal cord. The presynaptic fibers exit the spinal cord through anterior roots and enter the anterior rami of T1-L2 spinal nerves and onto the sympathetic trunks via white rami communicantes. From here, the fibers may ascend or descend the sympathetic trunk to a superior or inferior paravertebral ganglion, respectively, pass to adjacent anterior spinal nerve rami via gray rami communicantes, or cross through the trunk without synapsing and continue through an abdominopelvic splanchnic nerve to reach prevertebral ganglia. Because of the central location of the sympathetic ganglia, presynaptic fibers tend to be shorter than their postsynaptic counterparts. [2] [9]

Paravertebral ganglia exist as nodules throughout the sympathetic trunk, adjacent to the spinal column, where pre- and postganglionic neurons synapse. While the numbers may vary by individual, generally, there are three cervical, 12 thoracic, four lumbar, and five sacral ganglia. Of these, only the cervical have names of superior, middle, and inferior cervical ganglia. The inferior cervical ganglion may fuse with the first thoracic ganglion to form the stellate ganglion. [2] [9]

All nerves distal to the paravertebral ganglia are splanchnic nerves. These convey afferent and efferent fibers between the CNS and the viscera. Cardiopulmonary splanchnic nerves carry the postsynaptic fibers destined for the thoracic cavity.

Nerves that will innervate the abdominal and pelvic viscera pass through the paravertebral without synapsing, becoming abdominopelvic splanchnic nerves. These nerves include the greater, lesser, least, and lumbar splanchnic nerves. The presynaptic nerves finally synapse in prevertebral ganglia that are closer to their target organ. Prevertebral ganglia are part of the nervous plexuses that surround the branches of the aorta. These include the celiac, aorticorenal, and superior and inferior mesenteric ganglia. The celiac ganglion receives input from the greater splanchnic nerve, the aorticorenal from the lesser and least splanchnic nerves, and the superior and inferior mesenteric from the least and lumbar splanchnic nerves. The celiac ganglion innervates organs derived from the foregut: distal esophagus, stomach, proximal duodenum, pancreas, liver, biliary system, spleen, and adrenal glands. The superior mesenteric ganglion innervates the derivatives of the midgut: distal duodenum, jejunum, ileum, cecum, appendix, ascending colon, and proximal transverse colon. Lastly, the inferior mesenteric ganglion provides sympathetic innervation to the structures developed from the hindgut: distal transverse, descending, and sigmoid colon; rectum and upper anal canal; as well as the bladder, external genitalia, and gonads. [10] [11] [12]  For more information, see the relevant StatPearls article, at this reference. [13]

The two-neuron general rule for SNS and PNS circuits has several notable exceptions. Sympathetic and parasympathetic postganglionic neurons that synapse onto the ENS are functionally part of a three-or-more neuron chain. The presynaptic sympathetic fibers that are destined for the adrenal medulla pass through the celiac ganglia and synapse directly onto chromaffin cells. These unique cells function as postganglionic fibers that secrete epinephrine directly into the venous system. [1] [2] [14]

Postganglionic sympathetic neurons release NE that acts on adrenergic receptors in the target tissue. The subtype of the receptor, alpha-1, alpha-2, beta-1, beta-2, or beta-3, and the tissues in which they express influences the affinity of NE for the receptor. [15]  For more information, see the StatPearls articles related to adrenergic receptors, at the following references. [16] [17] [18]

As stated, the SNS enables the body to handle stressors via the “fight-or-flight” response. This reaction primarily regulates blood vessels. Vessels are tonically innervated, and in most cases, an increase in sympathetic signals leads to vasoconstriction and the opposite of vasodilation. The exceptions include coronary vessels and those that supply the skeletal muscles and external genitalia, for which the opposite reaction occurs. [2]  This contradictory effect is mediated by the balance of alpha and beta receptor activity. In a physiologic state, beta-receptor stimulation increases coronary vessel dilation, but there is blunting of this effect by alpha-receptor-mediated vasoconstriction. In a pathologic state, such as in coronary artery disease, alpha-receptor activity is enhanced, and there is the muting of beta-activity. Thus, the coronary arteries may constrict via sympathetic stimulation. [19]  Sympathetic activation increases heart rate and contractile force, which, however, increases metabolic demand and is thus detrimental to cardiac function in compromised individuals. [20]

The SNS is constantly active, even in non-stressful situations. In addition to the aforementioned tonic stimulation of blood vessels, the SNS is active during the normal respiratory cycle. Sympathetic activation complements the PNS by acting during inspiration to dilate the airways allowing for an appropriate inflow of air. [2] [21]

Additionally, the SNS regulates immunity through the innervation of immune organs such as the spleen, thymus, and lymph nodes. [15] [22]  This influence may up- or down-regulate inflammation. [23]  Cells of the adaptive immune system primarily express beta-2 receptors, while those of the innate immune system express those as well as alpha-1 and alpha-2 adrenergic receptors. [15] [24]  Macrophages activate by alpha-2 stimulation and are suppressed by beta-2 adrenergic receptor activation.

The majority of postganglionic sympathetic neurons are noradrenergic, and also release one or more peptides such as neuropeptide Y or somatostatin. NE/neuropeptide Y neurons innervate blood vessels of the heart, thus regulating blood flow, [25] while NE/somatostatin neurons of the celiac and superior mesenteric ganglia supply the submucosal ganglia of the intestine and are involved in the control of gastrointestinal motility. The thinking is that these peptides serve to modulate the response of the postsynaptic neuron to the primary neurotransmitter. [1]

Peptides also have associations with cholinergic sympathetic postganglionic neurons. These neurons are most commonly found innervating sweat glands and precapillary resistance vessels in skeletal muscle and produce vasoactive intestinal polypeptide along with ACh. Calcitonin gene-related peptide, a potent vasodilator, has also been discovered in paravertebral sympathetic neurons. [26] [27] [28] [29]

Parasympathetic Nervous System

Parasympathetic fibers exit the CNS via cranial nerves (CN) III, VII, IX, and X, as well as through the S2-4 nerve roots. There are four pairs of parasympathetic ganglia, and they are all located in the head. CN III, via the ciliary ganglion, innervates the iris and ciliary muscles of the eye. CN VII innervates the lacrimal, nasal, palatine, and pharyngeal glands via the pterygopalatine ganglion, as well as the sublingual and submandibular glands via the submandibular ganglion. CN IX innervates the parotid glands via the otic ganglion. [4]   Every other presynaptic parasympathetic fiber synapses in a ganglion near or on the wall of the target tissue; this leads to the presynaptic fibers being significantly longer than the postsynaptic. The location of these ganglia gives the PNS its name: “para-” means adjacent to, hence, “parasympathetic.” [2]

The vagus nerve, CN X, makes up about 75% of the PNS and provides parasympathetic input to most of the thoracic and abdominal viscera, with the sacral parasympathetic fibers innervating the descending and sigmoid colon and rectum.  The vagus nerve has four cell bodies in the medulla oblongata. These include the following [2] [4] [30] [31] :

• Dorsal nucleus: provides parasympathetic output to the viscera
• Nucleus ambiguus: produces motor fibers and preganglionic neurons that innervate the heart
• Nucleus solitarius: receives afferents of taste sensation and that from viscera, and lastly
• Spinal trigeminal nucleus: receives information of touch, pain, and temperature of the outer ear, the mucosa of the larynx, and part of the dura

Additionally, the vagus nerve conducts sensory information from baroreceptors of the carotid sinus and the aortic arch to the medulla. [32]

As mentioned in the introduction, the vagus nerve is responsible for the “rest and digest” processes. The vagus nerve promotes cardiac relaxation in several aspects of function. It decreases contractility in the atria and less so in the ventricles. Primarily, it reduces conduction speed through the atrioventricular node. It is by this mechanism that carotid sinus massage acts to limit reentry in Wolff-Parkinson-White syndrome. [2] The other key function of the PNS centers around digestion. Parasympathetic fibers to the head promote salivation, while those that synapse onto the ENS lead to increased peristaltic and secretory activity. [4] [33]  The vagus nerve also has a significant effect on the respiratory cycle. In a nonpathological state, parasympathetic nerves fire during expiration, contracting and stiffening airways to prevent collapse. This function has implicated the PNS in the onset of postoperative acute respiratory distress syndrome. [2] [21]

Due to the expansive nature of the vagus nerve, it has been described as an ideal “early warning system” for foreign invaders as well as for monitoring the body’s recovery. Up to 80% of vagal fibers are sensory and innervate nearly all major organs. Parasympathetic ganglia have been found to express receptors for interleukin-1, a key cytokine in the inflammatory immune response. [34] This, in turn, activates the hypothalamic-pituitary-adrenal axis and SNS, leading to the release of glucocorticoids and NE, respectively. [2] Studies have correlated inhibited vagal action through vagotomy and cholinergic inhibitors with significantly reduced, if not eliminated, allergic, asthmatic, and inflammatory responses. [7]

Postganglionic parasympathetic neurons release ACh that acts on muscarinic and nicotinic receptors, each with various subunits: M1, M2, and M3, and N1 and N2, with “M” and “N” standing for muscarine and nicotine, respectively. [5] The postganglionic ACh receptors and those on the adrenal medulla are N-type, while the parasympathetic effectors and sweat glands are M-type. [2] As in sympathetic neurons, several peptides, such as vasoactive intestinal peptide (VIP), Neuropeptide Y (NPY), and calcitonin gene-related peptide (CGRP) are expressed in, and released from, parasympathetic neurons. [27] [28] [35] [36]  For more information, see the StatPearls article on cholinergic receptors, here. [37]

Enteric Nervous System (ENS)

The ENS is composed of two ganglionated plexuses: the myenteric (Auerbach) and the submucosal (Meissner). The myenteric plexus sits in between the longitudinal and circular smooth muscle of the GI tract, while the submucosal plexus is present within the submucosa. The ENS is self-contained, functioning through local reflex activity, but often receives input from, and provides feedback to, the SNS and PNS. The ENS may receive input from postganglionic sympathetic neurons or preganglionic parasympathetic neurons. [1] [38]

The submucosal plexus governs the movement of water and electrolytes across the intestinal wall, while the myenteric plexus coordinates the contractility of the circular and longitudinal muscle cells of the gut to produce peristalsis. [39]

Motility is produced in the ENS through a reflex circuit involving the circular and longitudinal muscles. Nicotinic synapses between interneurons mediate the reflex circuits. [39] When the circuit activates by the presence of a bolus, excitatory neurons in the circular muscle and inhibitory neurons in the longitudinal muscle fire producing a narrow section of bowel proximal to the bolus; this is known as the propulsive segment. Simultaneously, excitatory neurons in the longitudinal muscle and inhibitory neurons in the circular muscle fire producing the “receiving segment” of the bowel in which the bolus will continue. This process repeats with each subsequent section of the bowel. [40]

The ENS maintains several similarities to the CNS. As in the CNS, enteric neurons can be bipolar, pseudounipolar, and multipolar, between which neuromodulation via excitatory and inhibitory communication. [1] Likewise, ENS neurons use over 30 neurotransmitters that are similar to those of the CNS, with cholinergic and nitrergic transmitters being the most common. [39]

While much of this discussion has focused on the efferent functions of the ANS, the afferent fibers are responsible for numerous reflex activities that regulate everything from heart rate to the immune system. Feedback from the ANS is usually processed at a subconscious level to produce reflex actions in the visceral or somatic portions of the body. The conscious sensation of the viscera is often interpreted as diffuse pain or cramps that may correlate with hunger, fullness, or nausea. These sensations most commonly result from sudden distention/contractions, chemical irritants, or pathological conditions such as ischemia. [41]

The peripheral nervous system derives from neural crest cells. The neural crest is divided axially into the cranial, vagal, truncal, and lumbosacral neural crest cells. Truncal neural crest cells contribute to the dorsal root of the spinal cord and the sympathetic ganglia. The parasympathetic innervation of the heart forms from the vagal neural crest. [42]  The majority of the parasympathetic nervous system, including all of the ganglia of the head, has been shown to arise from glial cells, rather than neural crest cells. [42] [43]

The ENS originates from the vagal neural crest with cells that migrate in a rostral-to-caudal pattern through the intestinal wall, forming a network of glia and neurons of various subtypes. [3] [39] [44]  Cells of the ENS complete their migration by four to seven weeks of development and express all varieties of ENS neurotransmitters by gestational week 24. However, mature gut motility is not realized until at least late gestation to shortly after birth. [45]

• Surgical Considerations

Horner syndrome is a mild, rare condition often presenting with unilateral ptosis, miotic, but a reactive pupil, and facial anhidrosis secondary to sympathetic nerve damage in the oculosympathetic pathway. [46] This damage may have a central cause such as infarction of the lateral medulla, or peripheral such as from damage secondary to thoracic surgery or from partial/total resection of the thyroid gland. [46] [47]  More centralized lesions tend to correlate with a constellation of symptoms that include Horner syndrome. [46] For more information, please see the associated StatPearls articles, here. [48] [49]  

Hyperhidrosis is a common disease characterized by excessive sweating, primarily of the face, palms, soles, and/or axilla. While the cause of primary hyperhidrosis is not fully understood, it has been attributed to increased cholinergic stimulation. Treatment can be either clinical or surgical. [50]  Treatment on the clinical side centers on anticholinergic agents such as topical glycopyrrolate or oral oxybutynin, or less commonly, alpha-adrenergic agonists such as clonidine, calcium channel blockers, or gabapentin. [50] [51]  The most common and permanent surgical technique is the resection, ablation, or clipping of the thoracic sympathetic chain. While permanent, the procedure may lead to compensatory hyperhidrosis in a small number of individuals. These hyperhidrosis symptoms are the same if not more severe than prior to the procedure due to possible overcompensation by the hypothalamus. Research has demonstrated that surgical reconstruction of the sympathetic chain can reduce this compensatory response. [52]

• Clinical Significance

Due to the extensive nature of the autonomic nervous system, it can be affected by a wide range of conditions. Some of these include [53] [54] [55]

• Amyloidosis
• Fabry disease
• Hereditary sensory autonomic neuropathy
• Diabetes mellitus
• Uremic neuropathy/chronic liver diseases
• Vitamin B12 deficiency
• Toxin/drug-induced: alcohol, amiodarone, chemotherapy
• Infections: Botulism, Chagas disease, HIV, leprosy, Lyme disease, tetanus
• Autoimmune: Guillain-Barre, Lambert-Eaton myasthenic syndrome, rheumatoid arthritis, Sjogren, systemic lupus erythematosus
• Neurological: multiple system atrophy/Shy-Drager syndrome, Parkinson disease, Lewy body dementia
• Neoplasia: Brain tumors, paraneoplastic syndromes

Likewise, autonomic neuropathy can present in nearly any system. Orthostatic hypotension is the most common autonomic dysautonomia, but numerous other, less understood, findings may present [53]

• Cardiovascular
• Fixed heart rate
• Postural hypotension
• Resting tachycardia
• Gastrointestinal
• Gastroparesis; nausea, vomiting, abdominal fullness
• Constipation
• Genitourinary
• Bladder atony
• Absent/delayed light reflexes
• Decreased pupil size
• Erectile dysfunction
• Retrograde ejaculation
• Gustatory sweating
• Cold extremities (due to loss of vasomotor responses)
• Edema (due to loss of vasomotor tone and increased vascular permeability)

The most prevalent symptoms of orthostatic hypotension are lightheadedness, tunnel vision, and discomfort in the head, neck, or chest. It may present concomitantly with supine hypertension due to increased peripheral resistance, which induces natriuresis, exacerbating orthostatic hypotension. There are numerous other, more benign stimuli that may either lower blood pressure (standing, food, Valsalva, dehydration, exercise, hyperventilation, etc.) or raise blood pressure (lying supine, water ingestion, coffee, head-down tilt, hypoventilation, etc.). [53]

Orthostatic hypotension evaluation is commonly done through orthostatic testing via repeated blood pressure and heart rate readings in supine and standing positions, but also through the use of the tilt-table test. However, the advantage of this latter test is minimal over the orthostatic test, with the main benefit being safety and convenience to the patient. [53]

Patients with dysautonomia are prone to hypotension during anesthesia [56] . This issue may be appropriately managed with low doses of phenylephrine, an alpha-1 agonist. Likewise, supine hypertension may be controlled with transdermal or IV nitrates. [53] [57] [58]

The sympathetic nervous system is well known to play a role in nociception. There are suggestions that the ANS has a regulatory inhibitory effect on pain, the loss of which creates a positive feedback circuit leading to hyperexcitability of nociceptive nerve fibers. The fact that the effect of sympathetic blocks often persists beyond the duration of the anesthetic agents administered supports this hypothesis. [59] Local sympathetic nerve blocks have been used to treat a variety of less-common pain conditions including complex regional pain syndrome, phantom limb pain, and herpetic pain. Likewise, visceral pain is treatable through a more central approach through a celiac plexus block. Due to the wide array of functions performed by the ANS, blocks are reserved for intractable pain, uncontrolled by more conventional analgesics. [59] See the related StatPearls articles for more information, here. [60] [61] [62]

Most conditions related to the ENS are congenital in origin and present during early childhood. [44] Enteric neurons function to relax intestinal smooth muscle. Their absence leaves the bowel tonically contracted, obstructing the bowel. Presenting complaints often consist of gastroesophageal reflux, dyspeptic syndromes, constipation, chronic abdominal pain, and irritable bowel syndrome. A notable life-threatening disorder of the ENS is Hirschsprung disease. This condition is a failure of embryologic ENS cells to colonize the distal bowel. When the ENS is missing (aganglionosis) or maldeveloped, children experience early constipation, vomiting, eventual growth failure, and possible death. [3] [44]  Studies have identified six genes in a causal relationship with Hirschsprung disease. [44] Down syndrome is the most common genetic disorder that predisposes an individual to Hirschsprung disease despite the fact that no genes related to ENS development have been identified on chromosome 21. [3]

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Schematic of the autonomic nervous system Contributed by Henry Gray (1918): Anatomy of the Human Body

Disclosure: Joshua Waxenbaum declares no relevant financial relationships with ineligible companies.

Disclosure: Vamsi Reddy declares no relevant financial relationships with ineligible companies.

Disclosure: Matthew Varacallo declares no relevant financial relationships with ineligible companies.

This book is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ), which permits others to distribute the work, provided that the article is not altered or used commercially. You are not required to obtain permission to distribute this article, provided that you credit the author and journal.

• Cite this Page Waxenbaum JA, Reddy V, Varacallo M. Anatomy, Autonomic Nervous System. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.

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Autonomic nervous system

Author: Jana Vasković, MD • Reviewer: Alexandra Osika Last reviewed: November 03, 2023 Reading time: 16 minutes

The autonomic nervous system (ANS) is a functional division of the nervous system, with its structural parts in both the central nervous system (CNS) and the peripheral nervous system (PNS). It controls the glands and smooth muscle of all the internal organs (viscera) unconsciously. This is why it’s also called the visceral nervous system. The other functional division of the CNS is the somatic nervous system, which mediates voluntary responses of the body. Together with endocrine glands, the ANS affects important body functions without an obvious involvement of the cerebral cortex .

Morphologically, the ANS is divided into central and peripheral parts. Functionally, the ANS is divided into sympathetic (SNS) and parasympathetic (PSNS) nervous systems. The ANS innervates:

• Smooth muscle (walls of the blood vessels, walls of the hollow organs)
• Cardiac muscle
• Glandular cells

This article will discuss the anatomy and the function of the autonomic nervous system.

Sympathetic nervous system

Parasympathetic nervous system, functions of divisions of the ans, orthostatic hypotension, dysfunctions of the urinary bladder.

The central part of the ANS consists of centers within the brainstem and the spinal cord , while the peripheral part is made up of autonomic fibers and ganglia of the PNS. SNS centers are found within the thoracic and lumbar segments of the spinal cord, which is why it is also called the thoracolumbar division. On the other hand, PSNS centers are found within the brainstem and sacral segments of the spinal cord, which is why it is also called the craniosacral division.

Autonomic fibers belong to peripheral nervous system and they are either afferent or efferent. Visceral afferent (sensory) fibers convey impulses from the internal organs to the centers of the SNS and PSNS. According to the information they bring, the autonomic centers convey efferent impulses through the visceral efferent (motor) fibers to the visceral organs and constantly regulate their function. These impulses are conveyed through ganglia and pre- and postganglionic nerve fibers.

Preganglionic (first-order) neurons are found within the gray matter of the CNS. Their axons (preganglionic fibers) synapse with the bodies of the postganglionic (second-order) neurons, which are found within autonomic ganglia. A ganglion is a neural tissue outside of the CNS which comprises of the neuronal bodies of the second-order neurons whose axons (postganglionic fibers) provide autonomic innervation to the organs.   SNS ganglia are found close to the SNS centers, in contrast with PSNS ganglia which are farther from the PSNS centers. Therefore, preganglionic SNS fibers are short, while postganglionic SNS fibers are long as they have the longer route to pass in order to reach their target tissues. For the PSNS, it is the other way around–preganglionic fibers are long, while postganglionic fibers are short as ganglia are found very close to their target organs.

What is special for both divisions of the ANS is that the conduction of impulses from centers to periphery happens through a series of two multipolar neurons , instead of a single neuron which you typically see in the central nervous system. A first-order neuron, or preganglionic neuron, is in the ANS centers, and its axons synapse with a second-order neuron found within the autonomic ganglia. 

In terms of physiology , a couple of things are important:

• All preganglionic fibers of the ANS release acetylcholine as a neurotransmitter .
• Postganglionic PSNS fibers release acetylcholine, while postganglionic SNS fibers release norepinephrine (noradrenalin) (except for those that supply the sweat glands which release acetylcholine).

The cell bodies of the SNS lays within the intermediolateral columns of the spinal cord gray matter (T1-L2/L3). In a transverse section of the spinal cord, the intermediolateral columns can be seen as the lateral horns of the spinal cord. The centers of the SNS give rise to preganglionic fibers, which synapse with SNS ganglia. SNS has two groups of autonomic ganglia: paravertebral and prevertebral.

Paravertebral ganglia are found on the left and right side of the body, parallel to the vertebral column (hence the naming paravertebral), and are linked together in a chain to form the left and right sympathetic trunk or sympathetic chain. Each trunk begins from the base of the skull with the superior cervical ganglion. The trunks unite at the level of coccyx and form the ganglion impar. 

Prevertebral ganglia (collateral ganglia, preaortic ganglia) lie anterior to the vertebral column, forming several plexuses around the major branches of the abdominal aorta , such as celiac ganglia around celiac trunk .

Preganglionic fibers leave the spinal cord through the anterior roots and anterior branches of spinal nerves as the white rami communicantes which then synapse with either paravertebral or prevertebral ganglia. Postganglionic fibers from the sympathetic trunk form the gray rami communicantes which enter the branches of all 31 spinal nerves.

Sympathetic innervation of the head and neck comes from the postganglionic fibers of the superior cervical ganglion of the sympathetic trunk and form multiple periarterial plexuses around the branches of the carotid arteries. Sympathetic innervation of the thoracic viscera comes from the cardiopulmonary splanchnic nerves, which contribute to cardiac, esophageal, and pulmonary plexuses. They are postganglionic fibers of the sympathetic trunk. 

Postganglionic SNS input for abdomen and pelvis comes from the abdominal and pelvic splanchnic nerves , which include the greater, lesser, and least thoracic splanchnic (T7-T11), and lumbar splanchnic nerves (T12-L3). Abdominal and pelvic sympathetic nerves are postganglionic fibers of the prevertebral ganglia. They form periarterial plexuses that surround the branches of the abdominal aorta.

The cell bodies of the PSNS are in the brainstem and S2-S4 segments of the spinal cord. PSNS has its ganglia placed near target organs of the abdomen and added to the branches of cranial nerves .

The brainstem centers provide cranial parasympathetic outflow. Preganglionic PSNS branches are added to the oculomotor (CN III), facial (CN VII), glossopharyngeal (CN IX), and vagus (CN X) nerves. They synapse with PSNS ganglia , which provide postganglionic fibers for the head and neck structures. The PSNS ganglia are the:

• Ciliary ganglion – added to the oculomotor nerve (CN III)
• Pterygopalatine ganglion – added to the facial nerve (CN VII)
• Otic ganglion – added to the glossopharyngeal nerve (CN IX)
• Submandibular ganglion – also added to the facial nerve (CN VII)

Sacral parasympathetic outflow originates from S2-S4 segments of the spinal cord. The preganglionic fibers exit the spinal cord via the anterior rami of spinal nerves, which form the pelvic splanchnic nerves. They synapse with PSNS ganglia found on or in the walls of their target organs. Thus, the postganglionic are very short. Sacral outflow supplies the descending colon , sigmoid colon , rectum , bladder , penis or clitoris .

SNS is the part of the ANS which is mostly active during stress, while the PSNS dominates during rest. Thus, the common phrase that describes the body state during SNS domination is “fight or flight”, while for the PSNS is “rest and digest”.

We presented the functions of the SNS and PSNS in the table above, and since there are many of them, now we’ll extract the ones that are a must-know:

The SNS stimulates the “fight or flight” response by:

• Contracting smooth muscle
• Contracting cardiac muscle by stimulating the heart conduction system
• Decreasing gland secretions, except for sweat glands

Contraction of smooth muscle of the vessels will lead to constriction of the vessels, and thus increased blood pressure. Stimulation of the heart conduction system leads to an increased heart rate, thus increased cardiac output, which contributes to increasing blood pressure. Contraction of the smooth muscles of the bronchi will lead to bronchodilation, and together with decreasing the secretion of the bronchial glands, will provide maximal respiratory capacity and more oxygen for muscles when fighting or running away.

Also, contraction of the dilator of the pupil muscle will result in mydriasis (dilation of the pupil). This increases the ability to detect visual information and increases alertness. Effects on metabolism reflect on stimulation of energy consumption. All of these effects increase the alertness of the body and mobilize energy to prepare the body for a fight or flight from a dangerous situation (“fight or flight”).

On the other hand, PSNS domination will promote “rest and digest” actions. The PSNS relaxes smooth muscles, leading to vasodilation. It slows heart rate through its effect on the conduction system of the heart, which together with vasodilation will decrease blood pressure. Contraction of the sphincter of the pupil muscle will lead to miosis (constriction of the pupil), and contraction of the ciliary muscle will lead to accommodation of the eye (changing the optical power of the eye in order to maintain a clear image or focus on an object as its distance varies).

Increased gland secretion mostly reflects to increased function of the gastrointestinal tract. Release of digestive juices and enzymes will increase digestion, and increased blood flow through the intestines will increase absorption of nutrients. In addition, the PSNS promotes anabolism, which means that it will stimulate the production and storage of energy. As we see, the PSNS redistributes the bloodstream to the intestines to pick up as many nutrients as possible and store it in energy deposits. Redirection of blood flow and decreased blood pressure reduce the alertness of the CNS, which altogether presents as a state of relaxation (“rest and digest”).

Clinical relations

Since the ANS innervates all body organs, disorders of the ANS may have a wide range of manifestations. Nevertheless, the key signs of ANS dysfunction are usually orthostatic (postural) hypotension, dysfunctions of the urinary bladder, or impotency.

This form of hypotension is called orthostatic or postural because a drop of blood pressure occurs when a person suddenly gets up from bed or stands up from a chair. This drop of blood pressure leads to hypoperfusion of the brain , which manifests as a quick onset of instability, blurry vision, and blackout.   Usually, this form of hypotension is not pharmacologically treated. It is advised to avoid situations which may lead to the onset of these symptoms. In rare cases when orthostatic hypotension significantly alters quality of life, medications such as sympathomimetics which imitates the effects of SNS are advised.

Damages of the SNS may lead to denervation of the internal sphincter of the urinary bladder. As this muscle is in charge of keeping the bladder closed until the moment of urination, its denervation will lead to involuntary emptying of the urinary bladder. On the other hand, the PSNS leads to contraction of the detrusor muscle of the urinary bladder and relaxation of the internal sphincter. If the PSNS is damaged, it will lead to difficulties in voluntary urination, with the involuntary leaking of urine only when the bladder is overfilled.

Parasympathetic stimulation is necessary for an erection in men and a normal libido in women. If the PSNS is damaged, it leads to the inability to have an erection (erectile dysfunction) and decreased libido. It is usually treated with medications that act through nitrogen-monoxide, since it is a strong dilator of blood vessels. This leads to filling of the cavernous bodies of the penis with blood, and consequent erection of the penis.

References:

• Drake, R. L., Vogl, A. W., & Mitchell, A. W. M. (2015). Gray’s Anatomy for Students (3rd ed.). Philadelphia, PA: Churchill Livingstone.
• Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2014). Clinically Oriented Anatomy (7th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.
• Fowler, T. J., Scadding, J. W., Losseff, N. A. (2011). Clinical Neurology (4th ed.). England, UK: Taylor & Francis.

Article, review and layout:

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Autonomic Nervous System

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Current understanding of cardiovascular autonomic dysfunction in multiple sclerosis

Affiliations.

• 1 Department of Neurology, Henry Ford Health, Detroit, MI, USA.
• 2 Division of Hypertension and Vascular Research, Department of Internal Medicine, Henry Ford Health, Detroit, MI, USA.
• 3 Department of Pharmaceutical Sciences, College of Pharmacy, Midwestern University, Glendale, AZ, USA.
• 4 Multiple Sclerosis Center of Excellence, Autoimmunity Center of Excellence, Arthritis and Clinical Immunology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA.
• 5 Department of Physiology, Wayne State University, Detroit, MI, USA.
• PMID: 39170118
• PMCID: PMC11337049
• DOI: 10.1016/j.heliyon.2024.e35753

Autoimmune diseases, including multiple sclerosis (MS), are proven to increase the likelihood of developing cardiovascular disease (CVD) due to a robust systemic immune response and inflammation. MS can lead to cardiovascular abnormalities that are related to autonomic nervous system dysfunction by causing inflammatory lesions surrounding tracts of the autonomic nervous system in the brain and spinal cord. CVD in MS patients can affect an already damaged brain, thus worsening the disease course by causing brain atrophy and white matter disease. Currently, the true prevalence of cardiovascular dysfunction and associated death rates in patients with MS are mostly unknown and inconsistent. Treating vascular risk factors is recommended to improve the management of this disease. This review provides an updated summary of CVD prevalence in patients with MS, emphasizing the need for more preclinical studies using animal models to understand the pathogenesis of MS better. However, no distinct studies exist that explore the temporal effects and etiopathogenesis of immune/inflammatory cells on cardiac damage and dysfunction associated with MS, particularly in the cardiac myocardium. To this end, a thorough investigation into the clinical presentation and underlying mechanisms of CVD must be conducted in patients with MS and preclinical animal models. Additionally, clinicians should monitor for cardiovascular complications while prescribing medications to MS patients, as some MS drugs cause severe CVD.

Keywords: Autonomic nervous system dysfunction; Cardiovascular diseases; Comorbidity; Epidemiology; Experimental autoimmune encephalomyelitis; Multiple sclerosis; Prevalence.

© 2024 The Authors.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Overview of multiple sclerosis (MS)…

Overview of multiple sclerosis (MS) etiology. The interplay between different components is involved…

Factors causing cardiovascular abnormalities in…

Factors causing cardiovascular abnormalities in patients with multiple sclerosis (MS). The primary factors…

• Pugliatti M., Rosati G., Carton H., Riise T., Drulovic J., Vecsei L., Milanov I. The epidemiology of multiple sclerosis in Europe. Eur. J. Neurol. 2006;13(7):700–722. doi: 10.1111/j.1468-1331.2006.01342.x. - DOI - PubMed
• Wallin M.T., Culpepper W.J., Campbell J.D., Nelson L.M., Langer-Gould A., Marrie R.A., Cutter G.R., Kaye W.E., Wagner L., Tremlett H., Buka S.L., Dilokthornsakul P., Topol B., Chen L.H., LaRocca N.G., Workgroup U.S.M.S.P. The prevalence of MS in the United States: a population-based estimate using health claims data. Neurology. 2019;92(10):e1029–e1040. doi: 10.1212/WNL.0000000000007035. - DOI - PMC - PubMed
• Wang H., Zhang X., Li H., Sun Z., Zhong Y. Gender differences in the burden of multiple sclerosis in China from 1990 to 2019 and its 25-year projection: an analysis of the Global Burden of Diseases Study. Health Sci Rep. 2023;6 doi: 10.1002/hsr2.1738. - DOI - PMC - PubMed
• Atlas of MS 2023. https://www.msif.org/resource/atlas-of-ms-2023/
• Charabati M., Wheeler M.A., Weiner H.L., Quintana F.J. Multiple sclerosis: neuroimmune crosstalk and therapeutic targeting. Cell. 2023;186(7):1309–1327. doi: 10.1016/j.cell.2023.03.008. - DOI - PMC - PubMed

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