includes all nerve fibers outside the brain & spinal cord; 

12 CN

31 SN

all their branches

behind the ear

primary auditory reception center with functions of hearing, taste, and smell

Wenicke's area

(temporal lobe)

Broca's area

(frontal lobe)

large bands of gray matter buried deep within the hemispheres;

form subcortical motor system (extrapyramidal)

help initiate & coordinate movement & control automatic associated movements of the body 

(e.g. the arm swing alternating with the legs during walking)

major respiratory center with basic vital functions:

temperature, appetite, sex drive, heart rate, and BP;

sleep center, anterior & posterior pituitary gland regulator;

coordinator of autonomic nervous system activity & stress response

most anterior part of the brainstem that still has the basic tubular structure of the spinal cord;

merges into the thalamus & hypothalamus;

contains many motor neurons & tracts

enlarged area containing ascending sensory & descending motor tracts;

has two respiratory centers (pneumotaxic & apneustic) that coordinate with the main respiratory center in the medulla 

continuation of the spinal cord in the brain that contains all ascending & descending fiber tracts;

has vital autonomic centers (respiration, heart, gastrointestinal function);

nuclei for CN 8-12

*pyramidal decussation (crossing of motor fibers) occurs here*

long, cylindric structure of nervous tissue about as big around as the little finger;

occupies the upper 2/3 of the vertebral canal from the medulla to lumbar vertribra L1-L2;

mediates reflexes of posture control, urination, & pain response

enter and exit brain rather than spinal cord

- 12 pairs -

atrophy with steady loss of neuron structure in brain and spinal cord;

people over 65 show general loss of muscle bulk, loss of muscle tone in face, neck, and around spine, decreased muscle strength, impaired fine coordination, and agility, loss of vibratory senses at ankles, decreased or absent Achilles reflex, pupillary miosis, irregular pupil shape, and decreased pupillary reflexes

*these findings would be considered abnormal in young adults*

-velocity of nerve conduction decreases making reaction to time slower in some older persons

-increased delay at synapse results in deminished sensation of touch, pain, taste, and smell

-motor system may show general slowing down of movement, muscle strength and agility decreases

-progessive decrease in cerebral blood flow and oxygen consumption may cause dizziness and loss of balance

-more likely than whites to have high BP

-tend to have strokes earlier in life & with more severe results than whites

-have almost 2x risk of first stroke compared with whites

deep tendon reflex has _ components:

1) intact sensory nerve (afferent)

2) functional synapse in the cord

3) intact motor nerve fiber (efferent)

4) neuromuscular junction

5) competent muscle

PNS composed of CN & SN

-somatic fibers innervate the skeletal (voluntary) muscles

-the autonomic fibers innervate smooth (involuntary) muscles, cardiac muscles, & glands

*ANS mediates unconcious activity*

sudden loss of strength, a temporary loss of consciousness (a faint), due to lack of cerebral blood flow

(e.g. low BP)

abnormal sensation 

(e.g. burning, tingling)

observe as the person walks 10 to 20 feet, turns, & returns to the starting point

-person should move with sense of freedom

-gait should be smooth, rhythmic, and effortless

-ask person to stand up with feet together & arms at the sides

-once stable, ask person to close the eyes & hold position for 20 seconds

-normally, a person can maintain posture and balance

*positive romberg sign = loss of balance that occurs when closing the eyes*

lower extremity coordination test

-ask person (in supine position) to place the heel on the opposite knee & run it down the shin from the knee to the ankle

4+ very brisk, hyperactive with clonus, indicative of disease

3+ brisker than average, may indicate disease, probably normal

2+ average, normal

1+ diminished, low normal, or occurs only with reinforcement

0 no response

set of rapid, rhythmic contractions of the same muscle

*occurs with upper motor neuron disease*

-use samme examination as with younger adults

-CN mediating taste & smell not usually tested but may show some decline in function

-decrease in muscle bulk most apparant in hand, dorsal hand muscles often look wasted, even with no apparant arthropathy, grip strength remains relatively good

-senile tremors occassionally occur (intention tremor of the hands, head nodding as if saying "yes" or "no", and tongue protrusion)

CN 1-anosmia

CN 2- defect or absent central vision

defect in peripheral vision, hemianopsia

absent light reflex

papilledema

optic atrophy

retinal lesions

1) LOC

2) motor function

3) pupillary response

4) vital signs

-ask person to squeeze your fingers

-offer your two fingers, one on top of the other, so that a strong hand grasp doesn't hurt your knuckles

-memory loss

-losing track

-forgetting words

-getting lost

-poor judgement

-abstract failing

-losing things

-mood swings

-personality change

-growing passive