PNS + ANS + Senses

Divisions of PNS

Sensory (afferent) and Motor (efferent)

Function of sensory division

Carry information to CNS

Function of motor division

Carry commands from CNS to effectors

Motor subdivisions

Somatic (voluntary) and Autonomic (involuntary)

ANS divisions

Sympathetic ("fight or flight") and Parasympathetic ("rest and digest")

Afferent vs efferent

Afferent = sensory to CNS; Efferent = motor from CNS

CN I Olfactory

Sensory — smell

CN II Optic

Sensory — vision

CN III Oculomotor

Motor — eye movement, pupil constriction

CN IV Trochlear

Motor — superior oblique muscle

CN V Trigeminal

Mixed — face sensation, chewing

CN VI Abducens

Motor — lateral rectus muscle

CN VII Facial

Mixed — facial expression, taste anterior 2/3

CN VIII Vestibulocochlear

Sensory — hearing and balance

CN IX Glossopharyngeal

Mixed — taste posterior 1/3, swallowing

CN X Vagus

Mixed — parasympathetic to organs

CN XI Accessory

Motor — SCM and trapezius

CN XII Hypoglossal

Motor — tongue movement

Cervical plexus innervation

Neck muscles and diaphragm (phrenic nerve)

Brachial plexus innervation

Upper limb

Lumbar plexus innervation

Anterior thigh (femoral nerve)

Sacral plexus innervation

Posterior thigh, leg, foot (sciatic nerve)

Phrenic nerve innervation

Diaphragm

Phrenic nerve function

Helps you breathe

Reflex arc

Receptor → sensory neuron → integration → motor neuron → effector

Mechanoreceptors

Detect touch/pressure; skin and ear

Thermoreceptors

Detect temperature; skin

Nociceptors

Detect pain; skin and organs

Chemoreceptors

Detect chemicals; taste buds and carotid bodies

Somatic motor neuron

Neuron controlling skeletal muscle

Sympathetic preganglionic cell bodies

Thoracolumbar spinal cord (T1-L2)

Parasympathetic preganglionic cell bodies

Brainstem and sacral spinal cord (S2-S4)

Sympathetic preganglionic neurotransmitter

ACh

Sympathetic postganglionic neurotransmitter

NE

Parasympathetic neurotransmitter

ACh for both pre- and postganglionic

Sympathetic effect on heart

Increases heart rate

Sympathetic effect on skeletal muscle vessels

Vasodilation

Sympathetic effect on sweat glands

Activates sweating

Sympathetic effect on respiratory system

Bronchodilation

Parasympathetic effects

Slows HR, bronchoconstriction, increases digestion

Tympanic membrane

Eardrum; vibrates with sound

Why rupture causes deafness

No vibration → no sound transmission

Middle ear contents

Ossicles: malleus, incus, stapes

Middle ear boundaries

Outer ear via tympanic membrane; inner ear via oval window

Function of ossicles

Amplify and transmit vibrations to oval window

Cochlear fluids

Scala vestibuli/tympani = perilymph; cochlear duct = endolymph

Pathway of sound

Auricle → canal → tympanic membrane → ossicles → oval window → cochlea → hair cells → CN VIII → thalamus → auditory cortex

Lobe for hearing

Temporal lobe

Lobe for equilibrium

Cerebellum and vestibular cortex (temporal)

Lens composition and function

Crystallin proteins; focuses light

Cells in retina

Rods, cones, bipolar cells, ganglion cells

Pathway of light

Cornea → pupil → lens → retina → optic nerve → thalamus → visual cortex

Lobe for vision

Occipital lobe

Rods

Low light; no color; peripheral vision

Cones

Color; sharp vision; bright light

General senses

Touch, pain, temperature, pressure

Special senses

Vision, hearing, taste, smell, equilibrium

Olfactory epithelium cells

Olfactory receptor cells, supporting cells, basal cells

Olfactory conscious perception

Olfactory cortex (temporal lobe)

Taste bud locations

Fungiform, foliate, circumvallate papillae

Filiform papillae

No taste buds; detect texture

Cranial nerves for taste

CN VII, IX, X

Special senses involving medulla

Taste, hearing, balance