Chapter 13 - The Peripheral Nervous System,

How do non-encapsulated nerve endings become exposed to stimuli, and what is a benefit of that?

Directly Exposed to Stimuli - very accurate

What type of receptors contain non-ecapsulated nerve endings, and what do they respond to?

Nocireceptors (pain) and Thermoreceptiors (temperature)

How do Encapsulated Nerve endings receive stimuli?

They are physically deformed

What type of receptors are encapsulated, and what do they respond to

Mechanoreceptors (physical touch)

Where are encapsulated nerve endings found?

Muscle spindles and tendon organs

In which type of nerve ending (non-encapsulated or encapsulated) is sensation adapted?

Encapsulated

What triggers pain?

Extremes (ex: extreme temp, pressure, chemicals, histamines, potassium, ATP, acids, bradykinin)

What type of fibers carry sharp pain impulses

small, myelinated fibers

what type of fibers cary burning pain impulses?

small, unmyelinated fibers

Which is felt first, on the onset of injury? Burning Pain or Sharp Pain

Sharp Pain

Why would pain need to be suppressed?

If pain cannot be stopped, It can be suppressed to dull the pain. Usually occurs in stressful situations

What hormones suppress pain?

Endorphins and Enkephalins

Visceral Pain

Painful stimulation of receptors of internal organs in thorax and abdominal cavity

Referred Pain

Pain stimuli arising from one part of the body is perceived from coming from another part

Why does referred pain occur?

Visceral pain afferents travel along similar routes as some somatic pain fibers, and brain cannot determine the exact location of the source, so the brain misinterprets the pain

What is a single axon surrounded in in nerves?

Endoneurium

What wraps around bundles of axons in a nerve?

Perineurium

What are groups of axons bundled together called in a nerve?

Fascicle

What wraps around the whole nerve structure?

Epineurium

What must happen for regeneration to occur in damaged axons of nerves in the PNS?

The cell body must be undamaged and the distance between severed ends must be short

How do regenerated axons differ from the original axons?

The nerve is smaller in diameter, which means it will send signals slower that before

What are the general steps of axon regeneration

1. Injury occurs; proximal portion seals off (to prevent further damage); distal portion degenerates (nothing keeping it alive)

2. Clean up; Macrophages destroy damaged portions of the axon because they will get in the way of regeneration

3. Axon Regeneration begins; Schwann cells release growth factor and proximal ends of axon will grow filaments; Schwann cells will form a tube to make sure nerve is growing in the correct directions

4. Complete regeneration; axon filaments continue to grow and fuse together; Schwann cells create new myelin sheets

Olfactory Nerve - Function

Smell

Olfactory Nerve - Type

Sensory

Olfactory Nerve - Damage

Lose some or all smell

Optic Nerve - Function

Vision

Optic Nerve - Type

Sensory

Optic Nerve - Damage

Full/Partial Blindness; Fuzzy vision; dots in vision

Oculomotor Nerve - Function

controls 4 of the 6 extrinsic eye muscles that moves the eye ball; allows eye movement

Oculomotor nerve - type

motor

Oculomotor nerve - damage

Eye misalignment/cross eye; cant follow gaze

Trochlear Nerve - Function

Innervates 1 of the 6 eye muscles, Superior Oblique; depresses eye and turns it laterally

Trochlear Nerve - Type

Motor

Trochlear Nerve - Damage

Pain or numbness in eye; double vision

Trigemial Nerve - function

sensory fibers to face and motor fibers to chewing muscles

Trigeminal Nerve - Type

Mixed

Trinomial Nerve - Damage

Difficulty Chewing

Abducens Nerve - Function

Controls 1 or 6 eye muscles, Lateral Rectus; moves eye outwards

Abducens Nerve - Type

Motor

Abducens Nerve - Damage

Cannot move eye out, pain/numbness

Facial Nerve - Function

Innervates facial expression muscles; contributes to taste

Facial Nerve - Type

Mixed

Facial Nerve - damage

Extensive - loss of taste; partial or full facial paralysis - drooping face

Vestibulocochlear Nerve - function

hearing and balance

Vestibulocochlear Nerve - type

Sensory

Vestibulocochlear Nerve - damage

Vertigo - extreme dizziness

Glossopharyngeal Nerve - Function

Innervates tongue for taste and pharynx for swallowing

Glossophyrgenal Nerve - Type

Mixed

Glossopharyngeal Nerve - Damage

Difficulty Swallowing, lost of taste, drooling

Vagus Nerve - Function

Organs in thorax and abdomen

Vagus nerve - type

mixed

Vagus Nerve - Damage

Servere - no control over respiratory system or heart system

Spinal Accessory Nerve - Function

move head and neck

Spinal Accessory Nerve - Type

Mixed

Spinal Accessory nerve - damage

limited head movement; pain when moving head

hypogloassal nerve - function

innervates tongue for chewing, speaking ,and swallowing

Hypoglossal Nerve - Type

Motor

Hypoglossal Nerve - Damage

Partial/ full loss of swallowing, chewing and speech

Are spinal nerves sensory, motor, or mixed?

Mixed

What is the general function or Dorsal Ramus?

provides sensory and motor fibers to skin and muscles in the back

what is the general function of ventral remus?

provides sensory and motor fibers to lateral and ventral body walls and upper and lower limbs

What are branches of nerve networks called?

Nerve Plexuses

Which Rami branches into nerve plexuses?

Ventral Ramus

How is a nerve plexus formed?

Ventral rami extend branch as they move away from the spinal cord, and form networks with branches from other rami

Effects of nerve plexuses

Each branch contains fibers from multiple spinal cords, which minimizes effects of damage. Fibers from each ramus travel to body by several routes

What areas does the Cervical Plexus supply?

Neck, ear, back of head, and shoulders

What is the major branch of the Cervical Plexus?

Phrenic Branch

What does the Phrenic Branch innervate?

The Diaphragm

What areas does the Brachial Plexus supply fibers to?

Upper body limbs

What are the major branches of the Brachial Plexus?

Median, Ulnar, Radial

What areas does the Median branch send motor function to?

Arm, Hand, Wrist

What movements movements for the median branch allow?

Flexion of wrist and fingers

What parts does the median branch receive sensory information from?

Lower arm and lateral parts of the hand

What parts do the ulnar nerve send motor information to?

Hand, Wrist, Fingers

What movements does the ulnar branch allow

Flexion of wrist and fingers

What parts does the ulnar branch receive sensory information from?

Pinky, half of ring finger, medial side of hand and forearm

What areas foes the radial branch send motor function to?

Wrist and Phalanges

What movements does the radial branch allow?

Extension

What parts does the radial branch receive sensors information from?

Back of arm, hand, and fingers

What does the Lumbar Plexus innervate?

Abdominal wall, anterior and medial thigh

What are the major branches of the lumbar plexus?

Femoral, Obturator

Where does the femoral branch send motor and receive sensory information from?

Anterior and medial portion of the leg

Where does the obturator branch send motor and receive sensory information from?

medial portion of the leg

What does the sacral plexus innervate?

buttocks, posterior part of lower limbs, pelvic structures, and perineum

What are the major branches of the sacral plexus?

Sciatic

Where does the sciatic branch send and receive motor and sensory infomation

Posteior and Lateral portion of thigh

What nerves does the Sciatic Branch contain?

Tibial, Common Fibular

Where does the Tibial nerve send and receive sensory and motor information from?

Posterior portion of leg and foot

What movements for the tibial nerve allow?

flexion at knee and dorsiflex of the foot

Where does the common fibular nerve send motor and receive sensory information from?

Anterior and Lateral portion of lower leg and foot

What movements does the Common Fibular Nerve allow

Point foot up

How are ventral Rami in the Anterolateral thorax and abdominal wall arranged?

in a segmental pattern

What area does ventral Rami in the Anterolateral thorax and abdominal wall serve?

Intercostal Muscles between ribs, skin of anterolateral thorax, most of abdominal wall

In what pattern does the dorsal rami innervate the back?

In a segmental patern

What type of reflexes are unlearned?

Intrinsic Reflex

What type of reflex requires learning and repetition?

Acquired

What does the brain do during a spinal reflex

the brain is notified of the reflex, but does not control it

What is the function of the Stretch Reflex?

Contracts muscle when the muscle is overstretched

Are Stretch reflexes monosynaptic or polysynaptic?

Monosynaptic

Are stretch reflexes ipsilateral or contralateral?

Ispilateral