chapter 13 - the peripheral nervous system

consists of all neural structures outside the brain and spinal cord

peripheral nervous system

what is the PNS divided into

sensory and motor components

transmits signals TOWARD the CNS

sensory division

sends commands FROM the CNS to effectors (muscles, glands)

motor division

controls skeletal muscle (motor division)

somatic system

regulates involuntary activity

autonomic nervous system

supports fight or flight response (part of autonomic nervous system)

sympathetic division

supports rest and digest functions (part of autonomic nervous system)

parasympathetic division

detect stimuli from internal and external environments and convert them into electrical signals through sensory transduction

sensory receptors

activation of sensory receptors

sensation

interpretation of sensory signal into meaningful information in brain

perception

bare dendrites; detect pain and temperature (receptor classification BY STRUCTURE)

free nerve endings

dendrites enclosed in connective tissue; detect pressure, vibration, and touch (receptor classification BY STRUCTURE)

encapsulated endings

detect light touch; deep in epidermis (receptor classification BY STRUCTURE, encapsulated endings)

meissner’s corpuscles

detect deep pressure; deep in dermis (receptor classification BY STRUCTURE, encapulated endings)

pacinian corpuscles

non-neuronal, detect specific stimuli; detect specific stimuli like light (photoreceptors)

specialized receptor cells

near external/body surfaces (skin, eyes); detect external stimuli (receptor classification BY STRUCTURE)

exteroceptors

monitor internal organs and blood vessels, monitor stretch, pH, pressure (receptor classification BY STRUCTURE)

interoceptors

detect body position and movement in muscles and joints (receptor classification BY STRUCTURE)

proprioceptors

detect chemical stimuli (taste, smell) (receptor classification by type of stimulus DETECTED)

chemoreceptors

detect osmotic pressure, fluid balance (receptor classification by type of stimulus DETECTED)

osmoreceptors

detect pain (chemicals from tissue damage) (receptor classification by type of stimulus DETECTED)

nociceptors

detect pressure, vibration, movement (receptor classification by type of stimulus DETECTED)

mechanoreceptors

detect temperature changes (receptor classification by type of stimulus DETECTED)

thermoreceptors

detect light (receptor classification by type of stimulus DETECTED)

photoreceptors

near external surfaces (skin, eyes, ears); detect external stimuli (receptor classification by LOCATION)

exteroceptors

internal organs, blood vessels, monitor stretch, pH, pressure (receptor classification by LOCATION)

interoceptors

in muscles, tendons, joints, detect body position, movement, muscle spindles and tendon organs (receptor classification by LOCATION)

proprioceptors

distributed throughout the body; include TOUCH, VIBRATION, TEMP, PAIN, PROPRIOCEPTION

general senses

localized to specific organs, include VISION, HEARING, BALANCE, SMELL, TASTE

special senses

groups of neuron cell bodies in the PNS

ganglia

bundles of axons in the PNS

nerves

contain cell bodies of unipolar sensory neurons (ex/dorsal root ganglion)

sensory ganglia

contain multipolar neurons for involuntary control

autonomic ganglia (sympathetic, parasympathetic)

regulate digestion

enteric ganglia

wraps the entire nerve

epineurium

surrounds each fascicle

perineurium

surrounds individual axons

endoneurium

blood vessels provide __

metabolic support

organized structure supports ___

signal transmission

these nerves connect to the spinal cord and are mixed nerves (carry both sensory or afferent and motor or efferent fibers); how many?

spinal nerves, 31; c1-8, t1-t12, l1-l5, s1-5, Co1

these nerves connect to the brain and may be sensory, motor, or mixed; how many?

cranial nerves, 12 pairs, I-XII

carries sensory fibers into the spinal cord (spinal nerve roots)

dorsal root

carries motor fibers out of the spinal cord (spinal nerve roots)

ventral root

contains sensory neuron cell bodies; found in the dorsal root of spinal nerves

dorsal root ganglion

spinal nerve roots are numbered…

based on section of the vertebrae and which intervertebral foramen they exit through

describe how cervical spinal nerves are numbered

matches vertebrae below

all other spinal nerve spinal nerves (t, l, s, spinal nerves) are numbered

matches vertebrae above

__ nerves form where dorsal and ventral roots merge at the _

spinal nerves, intervertebral foremen

true and false: spinal nerves are mixed with both sensory and motor fibers

true

carries sensory fibers

dorsal root

carries motor fibers out of the spinal cord

ventral root

spinal nerves t2-t12 are single nerves that go in BETWEEN each set of ribs and are referred to as

intercostal nerves

generally supply sensory and motor to upper back, check and abdomen

intercostal nerves

where multiple spinal nerves merge together to help bring multiple innervations for sensory and motor of muscles especially in the limbs

plexus

innervates neck, diaphragm

cervical plexus

supplies upper limbs

brachial plexus

anterior/medial thigh

lumbar plexus

posterior thigh and lower leg

sacral plexus

supplies motor to the diaphragm (type of cervical plexus)

phrenic nerve

types of briachial plexus

radial, ulnar, median, axillary nerve

motor to elbow, wrist, hand, finger extensors; sensory to posterior arm

radial nerve

motor to intricate hand muscles; sensory to pinky finger and half of ring finger

ulnar nerve

motor to thumb muscles, wrist flexors; sensory palm side of thumb, index, middle, and half of ring finger

median nerve

motor to deltoid; sensory over lateral shoulder

axillary nerve

motor to quads; sensory to anterior and medial thigh (lumbar plexus)

femoral nerve

motor to hamstrings, sensory to posterior thigh and entire lower leg (sacral plexus)

sciatic nerve

motor specifically to plantar flexors (ex/ gastrocenmius, soleus) (sacral plexus)

tibial nerve

motor specifically to dorsiflexors (ex/ tibialis anterior, extensor hallucis longus, fibularis longus and brevis)

common fibular nerve

saying to remember what each cranial nerve is

some say marry money but my brother says big brains matter most

say cranial nerves in order:

olfactory, optic, trochlear, trigeminal, abducens, facial, vestibulocochlear, glossopharyngeal, vagus, accessory, hypoglossal

sensory nerves of smell, pass through cribriform plate of ethmoid bone, olfactory bulb and tract

olfactory nerve (I)

purely sensory (visual) function, arise from retinas, pass through optic canal

optic nerve (II)

motor to eye muscles for eye movement

oculomotor nerve (III)

motor to eye muscles for eye movement

trochlear nerve (IV)

motor to muscle for mastication or chewing; 3 divisions= ophthalmic, maxillary, mandibular), sensory of the face

trigeminal nerve (V)

motor to eye muscle for eye movement

abducens nerve (VI)

motor to muscles of facial expression, sensory taste on the anterior tongue

facial nerve (VII)

sensory for hearing, sensory for equilibrium/balance

vestibulocochlear nerve (VIII)

motor to muscles of the pharynx for swallowing, sensory for taste of the posterior tongue, sensory of the pharynx

glossopharyngeal nerve (IX)

motor for parasympathetic control of rest and digest for the heart, lungs, and abdominal viscera, sensory for taste in the pharynx, sensation from viscera

vagus nerve (X)

motor to muscles of neck, back (trapezius, sternocleidomastoid)

accessory nerve (XI)

motor for muscle of the tongue for speech and swallowing

hypoglossal nerve (XII)

meaning a change in the membrane potential

depolarization