anatomy chapter 13

nerve

parallel bundle of peripheral axons

what is the nerve structure

epinerium, endocurium, and perinurium

endoncurium

surrounds an axon and associateed schwann cells

perineurium

surrounds bundles of axons (fascicles)

epineurium

encloses all fascicles (nerves)

classification of nerves

-mixed nerves

-afferent nerves

-efferent nerves

-most nerves are MIXED

mechanorecptors

touch, pressure, vibration, stretch

photorecptors

light

chemoreceptors

smell, taste, blood chemistry, and interstital chemistry

nociceptors

pain

exterorecptors

stimuli arising outside body

interoreceptors

stimuli arising inside body

propriceptors

bodys position, movement, stretch

simple receptors

the general sense (tactile, temperature, pain, muscle stretch)

can have either nonencapsulated "free" nerve endings or encapsulated nerve endings

special sense receptors

sight, smell, taste, hearing, balance

free nerve endings

temperature and pain

Thermoreceptors

outside the ranges pain receptors are activated

nociceptors

pain, temperature changes, pinch, release chemical from damaged tissue

modified free nerve endings

tactile/merkel discs, light touch

hair follicle receptors

bending hair

encapsulated nerve endings

almost all are mechonreceptors

tactile meissners corpuscles

discriminative touch

lamerllar pacinian corpuscles

deep pressure and vibrations

ruffni endings

deep and continuous pressure

muscle spindles

muscle stretch

tendon organ

tendo stretch

joint kinesthetic receptors

joint position and motion

what are the 3 levels of neural integration

receptor level, circuit level, perceptual level

when generating a signal what is requiered

-stimulus energy must match receptor specifiaty

-stimulus must be applied within receptor field

-energry of stimulus converted to a graded potential (transduction)

-GRADED POTENTIALS MUST REACH THRESHOLD

visceral pain

organs or thoracic and abdonminal cavity

how does afferent information travel

along same pathways as somatic pain fibers

referred pain

stimuli arising in one area is interpreted as coming from another part

olfactory(I)

special sensory nerves of smell

optic(II)

special sensory sight/visual

oculomotor (III)

motor, eye movement

Trochlear (IV)

superior oblique, motor-directs eyeball

Trigeminal (V) 3 divisions

-ophthalmic(V1)

-maxillary(V2)

-mandibular(V3)

what does the trigeminal do

convey general sensory impulses from various areas of face

v3 supply motor fibers for muscles of mastication

abducens (VI)

lateral retus muscle, motor innervation

facial (VII)

-motor; muscles of facial expressions

-parasympathetic; impulses to lacrimal and salivary glands

-special sensory; taste from anterior 2/3 of tongue

vestibulocochelar (VIII)

-mostly sensory

-hearing and balance

glossopharynge (IX)

-motor; part of tongue and pharynx for swallow

-parasympathetic; to paraotil glands

-sensory; taste and general sensory from pharynx to posteriior tongue carotid chemoreceptors and barorecptors

vagus (X)

-motor/parasympathetic; heart,lungs,abdominal

-sensory; taste from epiglottis

accessory (XI)

motor- scm ad trapizeus

hypoglossal (XII)

motor-extrinsic and intrinsic muscles of tongue for swallowing and speech

what are spinal nerves

all are mixed nereves

roots

-medial to and form spinal nerves

-each root is purely sensory or motor

rami

-distal to and are lateral branches of spinal nerves

-can carry both sensory and motor

dorsal horn

somatic and viscereal sensory interneurons

ventral horn

somatic motor neurons

lateral horn

visceral motor neurons

dorsal root

somatic and visceral sensory fibers

ventral root

somatic and visceral motor fibers

spinall nerve

mixed fibers

dorsal rami

mixed fibers for posterior body trunk

venteral rami

mixed fibers for anterior trunk and limbs

plexuses

-nerve plexuses; interlacing nerve networks made from ventral rami

what are the important plexuses

-cervical plexus (near neck)

-brachial plexus (arm)

-lumbar plexus (lower back)

-sacral plexus (pelvic)

cervical plexus

-most are cutaneous nerves that carry sensory input from the skin

-phrenic nerve(c3,c4,c5); motor and sensory to diaphragm

brachial plexus

-gives rise to virtually all nerves for upper limb

-MARMU; musculocutaneous,radial,ulnar

Musculocutaneous

biceps brachii, brachialis, coracobrachialis

axillary

deltoid and teres minor

radial

triceps brachii, brachioradialis

median

pronator teres, flexor carpi radialis

ulnar

flexor carpi ulnaris

lumbar plexus

-overlaps with sacral plexus

-innervate thigh, abdominal wall, psoas muscle

femoral nerve

quadricps and sartorius

obrurator nerve

adductor

sacral plexus

L4-S4

sciatic

-longest and thichest nerve

-innervates hamstring muscles, adductor magnus, most muscles in leg and foot

gluteal

gluteal and TFL muscles

Pudendal

-most skin and muscles of perineum

-external genitalia and anus

tibial

-muscular; most muscles of back of thigh leg and foot

-cutaneous;skin of posterior leg and sole of foot