peripheral nervous system

PNS

links cns with the body and external environment

• detects sensory stimuli and delivers info to CNS

• transmits response impulses from the CNS to effectors

somatic sensory division

sensory neurons transmit signals from the integumentary, muscular, and skeletal systems

• as well as special sensory signals

visceral sensory division

sensory neurons transmit signals from organs and abdominopelvic and thoracic cavities

somatic motor division

motor neurons that signal skeletal muscle fibers

controls voluntary motor functions

visceral motor division

autonomic nervous system- ANS

neurons signal cardiac muscle cells, smooth muscle cells, and secretory cells in glands

controls involuntary motor functions to maintain homeostasis

peripheral nerves

composed of the axons of many neurons bound together by a common connective tissue sheath

• mixed nerves- sensory + motor neurons

• sensory nerves- sensory neurons

• motor nerves- motor neurons

• spinal nerves- 31 pairs

• cranial nerves- 12 pairs

spinal nerves

originate from the spinal cord and mainly innervate structure inferior to the head and neck

• all mixed nerves

• 31 pairs

cranial nerves

originate from the brain and mainly innervate structure of the head and neck

• 12 pairs

endoneurium

nerve structure

olfactory (sensory)

I. smell

optic (sensory)

II. vision

oculomotor (motor)

III. eyes and eyelid movement; pupil constricting

trochlear (motor)

IV. eye movement

trigeminal (mixed)

V. facial sensation (touch and pain): mastication

abducens (motor)

VI. eye movement

facial (mixed)

VII. facial expressions; taste; salivation; tear secretion

vestibulocochlear (sensory)

VIII. hearing, balance

glossopharyngeal (mixed)

IX. taste, tongue, tonsil, and pharynx sensations, salivation, swallowing

vagus (mixed)

X. autonomic control of viscera( heart, lungs, digestive organs, glands)

accessory nerve (motor)

XI. spinal component - head and shoulder movement

cranial component- muscle of speech

hypoglossal (motor)

XII. tongue movements

cribriform plate

cranial nerve I

optical canal

cranial nerve II

superior orbital fissure

cranial nerve III, IV, VI, and V1

foramen rotundum

maxillary division

foramen ovale

mandibular division

internal acoustic meatus

cranial nerve VII AND VIII

jugular foramen

cranial nerves IX, X, AND XI

hypoglossal canal

cranial nerve XII

anterior root

posterior root

spinal nerve

spinal cord

anterior ramus

fibers to and from anterior side of body and or upper and lower limbs

posterior ramus

fibers to and from posterior side of body

axillary nerve

motor to the deltoid and teres minor muscle and sensory to the skin of the deltoid

radial nerve

motor to the triceps brachii, brachioradialis, and the extensor muscle

median nerve

motor to most muscles the flex the wrist and fingers

ulnar nerve

motor to certain forearm flexors and to most hand muscles

femoral nerve

anterior motor nerve to que quadriceps femoris, iliopsoas and sartorius

sciatic nerve

sensory to the hip joint

common fibular nerve

motor to the lateral leg muscles

sensory to the knee joint, the skin of distal leg

tibial nerve

motor to hamstring and plantar foot

sensory to knee joint ankle joint and skin of posterior lateral leg, and skin on plantar

exteroceptors

detects external stimuli

interoceptors

detect internal stimuli

mechanoreceptor

responds to mechanical force

thermoreceptors

responde to temp changes

photoreceptors

responde to light

chemoreceptors

responde to chemicals (in the air or fluids in body)

nociceptors

responds to damaging stimuli, causing pain

what leads to sensation and perception

• peripheral process transmits an action potential from the sensory receptor to neurons other axon, the central process

• the central process transmits an action potential from the peripheral process to the posterior horn, eventually synapsing on a neuron in the spinal cord or brainstem

main aspects of sensory perception

• the stimulus (pressure) is detected by receptors, generative a receptor potential, which triggers an action potential

• action potential is conducted along the peripheral process and transferred to the central process

• central process transmits the action potential to 2nd order sensory neurons of the CNS

• second order sensory neurons synapse on third order sensory neurons in the thalamus

• third order sensory neurons synapses on other interneurons in the primary somatosensory cortex

reflex arc

a neuronal pathway that controls a reflex action

1. sensory receptors detect stimulation

2. sensory neurons transmit info from receptors to CNS

3. integration center processes the info

4. motor neuron conducts a response impulse

5. effector responds to the motor neuron signal

interneuron

integration center

somatic nervous system

voluntary movements

touch, pain, temp, body postition

one motor neuron straight from muscle to the spinal cord

autonomic nervous system

involuntary movements

heart rate, breathing rate, blood pressure, digestion, swallowing, and pupil size

senses internal environment

used 2 neurons in “chains”

two divisions- sympathetic and parasympathetic

sympathetic

“fight or flight”

located in thoracic, lumbar, and spinal cord

a bunch of postganglionic cell bodies along the vertebral- SYMPATHETIC CHAIN GANGLIS

ganglion

• neuron(nucleus) cell bodies outside CNS

parasympathetic

“rest and digest”

located in brainstem or sacral spinal cord

adrenergic receptors

bond epinephrine and norepinephrine

• INCLUDES ALPHA AND BETA RECEPTORS

cholinergic receptors

bind acetylcholine (ACh)

• INCLUDES MUSCARINIC RECEPTORS AND NICOTINIC RECEPTORS