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Flashcards in CNS Ch 12 Deck (56):
1

Sensory receptors

Specialized to respond to changes in environment called stimuli

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Classification by stimulus type

Mechanoreceptors
Thermoreceptors
Chemoreceptors
Photoreceptors
Nociceptors

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Mechanoreceptors

Respond to mechanical force such as touch, pressure, vibration, and stretch

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Photoreceptors

Respond to light, such as those in the retina.

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Chemoreceptors

Respond to chemicals in solution ( molecules smelled or tasted, or changes in blood or interstitial fluid chemistry)

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Nociceptors

Respond to potentially damaging stimuli that result in pain (extremes of cold and heat, excessive pressure and inflammatory chemicles

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Classification by location

Exteroceptors: Outside the body
Internoceptors: Within the body
Proprioceptors:

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Proprioceptors

Occure in skeletal muscles, tendons, joints, ligaments and connective tissues or bones and muscles

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Simple receptors of general sences

Non-encapsulated (free) nerve endings
Encapsulated nerve endings

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Non-encapsulated nerve endings

Non-mylinated, small diameter and have knob like distal ends
Nearly everywhere, abundant in epithelial and connective tissue.
Examples: Tactile (merkel) disk in skin and Hair follicle receptors

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Encapsulated nerve endings

ONe or more fiber terminal enclosed in connective tissue capsule
Tactile corpuscles
Lamellar corpuscle
Bulbous corpuscles
Muscle spindles
Tendon organs
Joint kinethetic receptors

12

Somatosensory system

Part of the sensory system serving the ody wall and limbs. Receives input from exteroceptors, interoceptors and proprioceptors

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3 levels of neural integration

Receptor level: sensory receptors
Circuit level: processing in ascending pathways
Perceptual level: processing in cortical sensory areas

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Perceptual detection

Ability to detect that stimulus has occured

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Magnitude estimation

Ability to detect how intense the stimuli is

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Spatial discrimination

Ability to identify the site and pattern of stimuli

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Feature abstration

The ability to identify multiple features of an object

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Quality discrimination

Ability to identify submodalities of a sensation, eg. sweet or bitter.

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Patter recognition

Ability to recognize a familiar or unfamiliar pattern, or a special significance.

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Visceral Pain

Results from noxious stimulation of receptors in thorax or abdomen.
Vague, dull, aching or burning

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Referred pain

Arises from one part of the body but is perceived in another part.

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Nerve

Cord like organ, consists of multiple fascicles full of axons and a blood supply

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Nerve structure

Endoneurium: encloses each axon
Perineurium: surrounds each fascicle
Epineurium: encloses all fascicles, outer sheath of nerve.

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Regeneration of PNS nerves

1. Axon fragments at injury site
2. Macrophages clean out the dead axon
3. Schwann cells form regeneration tube and axon sprouts grow through tube.
4. Axon regenerates and new myelin sheath forms

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I Olfactory

Tiny nerve filaments of sense of smell
SENSORY ONLY

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II Optic

SENSORY ONLY, nerve of vision, outgrowth of the brain so it is actually a tract.

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III Oculomotor

MOTOR ONLY, "eye mover", supplies the 4 extrinsic muscles that move the eyeball up down and inward.

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IV Trochlear

MOTOR ONLY, "pulley" innervaed the extrinsic eye muscle that rotate eye inferolaterally

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V Trigeminal

SENSORY & MOTOR to the face and chewing muscles

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VI Abducens

MOTOR. Controls eye abduction

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VII Facial

MOTOR & SENSORY, controls muscles of facial expression

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VIII Vestibulocochlear

SENSORY, for balance and hearing.

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IX Glossopharyngeal

SENSORY & MOTOR for tongue and pharynx

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How many spinal nerve pairs are there

31
8 cervical (C1-C8)
12 thoracic (T1-T12)
5 lumbar (L1-L5)
5 sacral (S1-S5)
1 coccygeal (C0)

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DAVE

Dorsal root = Afferent, Ventral root = Efferent

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Nerve Plexis

Ventral rami branch and join one another laterally forming complicated interlacing nerve networks

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Cervical Plexus

C1-C4
Under SCM
mostly supply cutaneous nerves
and muscles of anterior neck

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Phrenic nerve

Fibers from C3, C4 & C5
motor and sensory for the diaphragm

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Brachial Plexus

Nerves that innervate upper limb
C5-C8 and T1

40

Really Tired Drink Coffee

Brachial plexus branches from medial to lateral:
1) Roots
2) Trunks
3) Divisions
4) Cords

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Nerves of brachial plexus

Axillary
Musculocutaneus
Median
Ulnar
Radial

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Axillary

innervated deltoid, teres minor, shoulder skin and joint

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Musculocutaneus

Biceps brachii, brachialis and coracobrachialis

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Median

5 muscles of lateral palm, pronates foreare, flex wrist and thumb and index finger

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Ulnar

Medial part of forearm and the last 3 fingers, flexors not supplied by median nerve

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Radial

Extend the elbow, supinate forearm, extend wrist and fingers, and abduct the thumb.

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Lumbosacral Plexus

L1-L4
Within Psoas major muscle
Innervates abdominal wall and psoas muscle, anterior and medial thigh

48

Femoral nerve

Largest terminal nerve in lumbar plexus
Innervates quadriceps and knee extensors.

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Obturator nerve

innervates adductor muscles through obturator foramen

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Sacral plexus

L4-S4
Innervates butt ox lower limb pelvic structures and perineum

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Sciatic nerve

Largest nerve in sacral plexus
thickest and longest in the body
supplies entire lower limb except anteromedial thigh.

52

Hilton's Law

Any nerve serving a muscle that produces movement also innervates the joint and skin over the joint.

53

Hierarchy of motor control

Precommand
Projection
Segmental

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Precommand level

Highest level, cerebellum and basal nuclei, programs and instructions.

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Projection level

Middle level, motor cortex and brain stem nuclei (vestibular and reticular formation ect)

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Segmental Level

Lowest level, Spinal cord,contains central pattern generators.