The Nervous System

Perry C. Hanavan, Au.D.

Learning Outcomes

• Outline the basic anatomy of the nervous system• Understand anatomical divisions:

– Central nervous system– Peripheral nervous system

• Understand functional divisions:– Somatic nervous system– Autonomic nervous system

• Explain the functions of the major structures of the nervous system

Question

Which of the following is a part of the peripheral nervous system?

A.Brain

B.Spinal nerves

C.Spinal cord

D.Cranial nerves

E.B and DSenteo QuestionTo set the properties right click and select Senteo Question Object->Properties...

Anatomical divisions

CENTRALNERVOUSSYSTEM SPINAL CORD

BRAIN

PERIPHERALNERVOUSSYSTEM SPINAL NERVES

To & from spinal cord

CRANIAL NERVESTo & from brain

The nervous systembrain

spinal cord

peripheralnerves

Role of the nervous system

• To monitor the internal and external environment of the body

• To process this information• To direct behaviour and body processes

Question

The skeletal muscles belong to the:

A.SNS

B.ANS

C.CNS

D.I have no idea

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Functional divisions

Somatic nervous system: voluntary, controls skeletal muscleAutonomic nervous system: involuntary, controls smooth muscle

Neurons

Synaptic Junction

Glial Cell: Astrocyte - Provides Transport of

Nutrients to Neuron – Shields Toxins

Excitatory/Inhibitory

Types of Neurons

Meningeal Linings of Brain

Features of the PNS (1)

• Structure of a peripheral nerve

• Bundles of axons packaged together

• Carry motor, sensory and autonomic info

peripheral nerve

epineurium

perineurium

nervefibre

endoneurium

myelin sheath

axon

Features of the PNS (2)

Nerve

Afferent

Efferent

Ganglion

Features of the PNS (3)

Mattergrey matter white matter

Braincerebral

hemisphere

brainstem

cerebellum

View from Below

Lobes

planning, emotion,mood, behaviour, motor function, smell

hearing, language, memory

basic body functions

touch, pain, temperature sensation

vision

balance, coordination

Brain

Meninges

Brain Ventricles

Produce and contain CSFCSF circulates to subarachnoid space

Spinal Cord

Spinal Cord

a

spinal cord

vertebral body

nerve root

intervertebral foramen

a = ganglion

Neurons

Ventricles

Cerebral Cortex

Brodmann Map

Motor Strip

Limbic System

MRI

Cerebral CortexFunctional Divisions Display

Basal Ganglia

Limbic System

Brainstem

Brainstem

Midbrain

Cranial Nerves

• I-Olfactory, II-Optic, III-Oculomotor, IV-Trochlear, V-Trigeminal, VI-Abducens, VII-Facial, VIII-Acoustic (Vestibulocochlear), IX-Glossophrayngeal, X-Vagus, XI-Spinal Accessory, XII-Hypoglossal

• On Old Olympus Towering Tops, A Finn And German Viewed Some (A) Hop(s)

• Some Say Marry Money, But My Brother Says Big Bucks Makes Money 

Cranial Nerve

SMB

Function Innervation Symptom/sign of damage

I Olfactory S Smell Mucosa of nose Anosmia

II Optic S Vision Retina of eye Blindness

III Oculomotor M Eye movement(elevation, adduction)

Eye muscles Eye deviates down & outPupillary/accommodation reflexes absent

IV Trochlear M Eye movement

Eye muscle Diplopia, lateral deviation of eye

Cranial Nerve

SMB

Function Innervation Symptom/sign of damage

V Trigeminal B Facial sensationMastication

Sensory: Cutaneous senses of face, eyes, scalp, nasal mucosa, teeth, and anterior 2/3rd of tongueMotor: mastication

Facial aneasthesia Loss of pain sensationWeakness/loss of mastication

VI Abducens M Eye movement (abduction)

Eye muscle Medial eye deviation

VII Facial B Facial expresssion TasteSalivation Lacrimation

Motor: Muscles of facial expression and scalpSensory: Taste from anterior 2/3rds of tongue

Paralysis of facial nerve musclesLoss of taste (anterior 2/3rds of tongue)Dry mouth, loss of lacrimation

VIII Auditory/Vestibular

S BalanceHearing

Semicircular canals and utricle and sacculeCochlea

Vertigo, dysequilibrium, nystagmusHearing loss

Cranial Nerve

SMB

Function Innervation Symptom/sign of damage

IX Glossopharyngeal

B TasteSalivationInnervation of pharynx

Sensory: Posterior 1/3rd of tongueMotor: Mucosa and elevator muscles of pharynx and parotid gland

Loss of taste (posterior 1/3rd of tongue)InsignificantLoss of gag reflex

X Vagus B Swallowing & talkingCardiac, GI tract, respirationTaste

Motor: Palatal muscles, pharyngeal constrictors, vocal cordsSensory: Taste sensation to epiglottis

Dysphagia & hoarseness of voiceLoss of cough reflex (larynx/pharynx), loss of taste (hard palate)

XI Spinal accessory

M Pharynx/larynx musclesNeck & shoulder movement

Laryngeal and pharyngeal musclesHead rotation and shoulder shrugging

Head turning/shoulder shrugging weakness

XII Hypoglossal M Tongue movement

Intrinsic and extrinsic muscles of tongue

Atrophy of tongue muscles, deviation on protrusion, fasciculations

Olfaction I

Optic II

Oculomotor III

Trigeminal V

VII Facial Nerve

Auditory VIII

Spinal Accessory XI

• CERVICAL SPINAL NERVES:

• c345 keeps the phrenic alive (innervation of phrenic nerve) c345 keep the diaphragm alive (innervation of diaphragm)

• c5-6-7 raise your arms to heaven (nerve roots of long thoracic nerve innervate serratus anterior)   

Patellar Reflex

Anterior Spinothalmic Tract

• Sense of light touch (sensory)

Upper Motor Neuron

Corticospinal Pathway

Corticobulbar Pathway