class 3 the nervous system and somatic and special senses

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Class 3 The Nervous System and Somatic and Special Senses

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Class 3

The Nervous Systemand

Somatic and Special Senses

Peripheral Nervous SystemCranial Nerves and Spinal Nerves

Cranial Nerves•12 Pairs of nerves that originate on the brain.

I - Olfactory II - Optic III - Oculomotor IV - Trochlear V - Trigeminal VI - Abducens VII - Facial VIII - Auditory IX - Glossopharyngeal X - Vagus XI - Accessory XII - Hypoglossal

Spinal Nerves

• 31 pairs of spinal

nerves (mixed nerves)– 8 cervical (C1 – C8) C1

between skull and atlas– others exiting at

intervertebral foramen

– 12 thoracic (T1 – T12)

– 5 lumbar (L1 – L5)

– 5 sacral (S1 – S5)

– 1 coccygeal (Co)

Spinal cord

Anterior median fissure

Pia mater

Denticulateligaments

Dorsal root

Ventral root, formed byseveral “rootlets” fromone cervical segment

Arachnoid mater(reflected)Dura mater (reflected)

Spinal blood vessel

Receptor

Sensory neuron

Integration center

Motor neuron

Effector

Spinal cord(in cross section)

Interneuron

Stimulus

Skin

1

2

3

4

5

Reflex Arc

Patellar Reflex

Withdrawal Reflex

Nerve Plexus

• Where 2 or more nerves come together, are re-sorted, and form a new nerve

• Include:– Cervical– Brachial– Lumbosacral

Cervical PlexusC1 – C4

Brachial PlexusC5 – T1

Lumbosacral PlexusL1 – L4

& L4 – S3

Peripheral NervesPhrenic Nerve diaphragmAxillary Nerve armpitMedian Nerve** associated with carpal tunnel syndromeUlnar Nerve medial forearmRadial Nerve posterior arm, lateral forearm, posterior

handMusculocutaneous Nerve muscles and skin of armSciatic Nerve** posterior thigh to bottom of foot to big toe; splits into Tibial and Fibular at knee; largest

and longest nerve in the body; can oftenbeen impinged by the piriformis muscle

Femoral Nerve** anterior and lateral thighObturator Nerve pelvis

Cervical plexus Brachial plexus Lumbosacral plexus

Dermatomes • A dermatome is

a region of the skin supplied by a single spinal nerve.

C2C3

C2

C3 C3

C2C3

N V

C5

C5

C4

C4

C6

C7C6

T2

T1T2T3T4T5T6T7T8T9T10

T11

T12

T2T3T4T5T6T7T8T9T10T11T12L1L2

L3L4L5

L1

T1

T2

C8

C7

C8

L2

L3

L4

T1 L1

L2

L5

S5

S

S1

S2

4S3S2

S1

L3

L4

L5

ANTERIOR POSTERIOR

Shingles

Autonomic Nervous SystemParasympathetic and Sympathetic

Sympathetic Division“Fight or Flight”

Thoracolumbar division it’s branches come from the

T₁ – L₂ or L₃

Effects

heart rate, breathing rate,sweating, pupil size, blood vessel size to skeletal muscle, adrenal gland secretions

intestinal function and saliva

Parasympathetic Division“Rest and Digest”

CranioSacral Division it’s branches come from

the CNs III, VII, IX, X and S₂, S₃, and S₄

Effects:•Increase Intestinal Activity and saliva•Decrease Heart Rate•Slower, deeper breathing•Constricts pupils

Role of Massage Therapy in Autonomic Nervous System Function

Stimulates a Parasympathetic

response

Relaxation!Relaxation!Relaxation!

Exception: Pre-event Massage/Sports Massage – which is

designed to “stimulate” the body to prepare it for the event about to take

place

Somatic and Special Senses

5 Types of Receptors:Chemoreceptors

Detect chemical concentrations in an aqueous solutionsex) taste buds and receptors of the nose

Pain ReceptorsDetect damage to tissueex) free nerve endings throughout body

ThermoreceptorsDetect changes in temperatureex) receptors found throughout skin and more

MechanoreceptorsDetect changes in pressure or movementex) receptors found in skin, inner ear and more

PhotoreceptorsDetect light energyex) rods and cones – the visual receptors

Sensations•All impulses (information) entering the CNS are virtually the same.

• The brain sends the signals to specific areas of the brain for interpretation.

•All sensation is subjective.

•Sensation is projected back to the site of the original stimulus, which makes us think we sense it at that point.

•Many senses will adapt, impulses rates will decrease.

Somatic SensesTouch, Pressure and Vibration

Temperature Sensation2 categories of Thermoreceptors:

Hot and Cold receptors.

• Cold receptors – Most stimulated between 77º F and 41º F. Below that and area goes numb.

• Hot receptors – Perceive hot sensations above 86º F and are most stimulated at 113º F.

• Free Nerve Endings: Detect as burning sensation when temp is above 113⁰ or detect as numbing when temp is below 41⁰.

• Thermoreceptors are found all over the body, with highest concentration found in the face and ears (hence why your nose and ears always get colder faster than the rest of your body on a chilly winter day).

Pain Sensation• Acute Fibers (A-Delta

fibers)– sharp, myelinated,

remove stimulus & pain goes away

• Chronic Fibers (C fibers)– dull, unmyelinated,

remove stimulus & pain stays

Visceral Pain and Referred Pain

Regulation of Pain Impulses

Endorphins and EnkephalinsOur Natural Pain Killers – special chemicals that when

released slow down the pain fiber impulses hence lessening pain.

Muscle and Tendon Proprioception

Muscle Spindles Golgi Tendon Organs

Special Senses

Sense of SmellOlfaction

Sense of TasteGustation

Sense of Sight

• Hyperopia (farsightedness) – difficulty focusing on objects near the face.

• Myopia (nearsightedness) – difficulty focusing on distant objects.

• Astigmatism - An irregular shaped cornea or lens prevents light from focusing properly on the retina. Images focus at multiple points on retina

Sense of Hearing/Equilibrium

Hearing Cochlea of the Inner Ear

Organ of Corti – hearing receptor

Static Equilibrium

• As the head moves, the thick fluid above the receptor cells, weighted with otoliths, pulls on the cilia of the cells, generating a nerve impulse

Dynamic Equilibrium

• As the body spins or moves in different directions, the cilia bend as the head changes position, generating nerve impulses.

EXAM REVIEW

This…….is….…JeopardyNervous System The BrainNeurons Senses

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Peripheral Nervous System

Thank goodness!!!