1. Anatomy & Physiology Ch. 10

2.  Brain & Spinal Cord

3.  3 Support Structures of S.C.  Vertebrae  Vertebral foramen allows creates bony protective casing for the s.c.  Meninges  3 layers of connective tissue that encircle the brain & spinal cord  Cerebrospinal Fluid  Fluid that acts as a shock absorber for the brain and s.c.

4.  Dura Mater  Outermost layer  “tough mother”  2 nd sacral vertebrae  brain  Epidural space = fat & connective tissue that surrounds dura mater

5.  Arachnoid Mater  Middle layer  Named b/c of its spider- like arrangement of c.t.  Subdural space is b/t it and the dura mater = interstitial fluid

6.  Pia Mater  Adheres to the surface of the spinal cord and brain  Within are blood vessels that supply oxygen & nutrients to the brain & s.c.  Subarachnoid space – b/t arachnoid/pia mater, houses the cerebrospinal fluid

7.  Anesthetic measure where a long needle is inserted into the subarachnoid space b/t L3-L4 or L4-L5  Less danger of hitting spinal cord  cord ends at L2

8.  All three spinal meninges cover the spinal nerve roots up to the point where they exit the spinal column through the intervertebral foramina  Denticulate ligaments – thickenings of the pia mater that project laterally and connect to the arachnoid mater and dura mater protecting the s.c. from sudden displacement or shock

9.  Approx. 16-18 in. in length ◦ Extends from medulla oblongata  upper border of second lumbar vertebrae  Does not extend length of vertebral column ◦ Cauda Equina = horse’s hair; extensions of nerves running caudally to the second lumbar vertebrae

10.  Two major areas of nervous tissue ◦ Cervical Enlargement: nerves supplying upper limbs ◦ Lumbar Enlargement: nerves supplying lower limbs  Anterior Median Fissure & Posterior Median Sulcus ◦ Divide S.C. into 2 equal halves

11.  Gray Matter ◦ Cell bodies of neurons, neuroglia, unmyelinated axons, & dendrites ◦ Subdivided into halves known as gray horns  Anterior Gray Horns – contain cell bodies of somatic neurons controlling skeletal muscle  Posterior Gray Horns – contain somatic and autonomic sensory neurons  Lateral Gray Horns – control smooth muscle, cardiac, and glandular control of autonomic n.s.

12.  White Matter ◦ Columns of myelinated and unmyelinated axons of sensory neurons, interneurons & motor neurons ◦ Contain tracts of neurons carrying impulses to specific areas of the body ◦ Name of the tract indicates its position in the white matter, where it begins and ends, and the direction of the nerve impulse  Ex. Anterior spinothalmic tract

13.  Spinal nerves connect the s.c. to the nerves that correspond w/ specific body parts  Posterior roots of spinal nerves contain only axons of sensory neurons ◦ Posterior root ganglia contain sensory cell bodies  Anterior roots of spinal nerves contain only axons of somatic motor neurons, and autonomic motor neurons

14.  Maintaining Homeostasis  White matter serves as highways for nerve impulses  Impulses can travel up and down s.c., toward brain, or away from brain  Gray matter of s.c. receives and integrates incoming and outgoing info. and is the site of reflex integration  Reflex arc is the pathway followed by nerve impulses that produce a reflex  Spinal – integration in s.c.  Cranial – integration in brain stem  Ex. Patellar reflex

16.  31 pair of spinal nerves  1 pair emerge above the atlas, the rest run through intervertebral foreamen  Composition ◦ Contains both sensory and motor axons except in the roots  Coverings ◦ endoneurium – surrounds axons ◦ Fascicles – bundles of axons ◦ Perineurium – layer surronding fascicles  Extensive vascular network b/t peri & epi ◦ Epineurium – covers entire nerve  Distribution ◦ Plexus – network of adjacent nerve axons the join together ◦ many spinal nerves do not extend directly to the body structures they supply

17.  Brain Stem ◦ Cont. w/ S.C. ◦ Medulla, pons, midbrain  Diencephalon: above brain stem ◦ Thalmus, hypothalmus, pineal gland  Cerebrum: bulk of brain ◦ Supported by brain stem & diencephalon ◦ Gray matter surrounds white matter  Cerebellum: posterior to brain stem

18.  Weight = 2% body weight  Oxygen supply = 20% of total  4 or more minutes of Oxygen deprivation = permanent damage  Glucose Supply  Must be continuous  No glucose stared in brain  Blood Brain Barrier (BBB)  Prevents passage of harmful substances  Does not prevent lipid-soluble substances  Trauma can decrease effectiveness

19.  Function  Carries oxygen, glucose, other chemicals to neurons  Removes waste and toxic substances  Besides moving in the subarachnoid space it also circulates through the ventricles of the brain  Lateral, third & forth ventricles  Chorocoid plexuses make CSF w/ help from ependymal cells  Filter blood plasma  CSF absorbed by arachnoid villi & drains into superior sagittal sinus  Volume = 80-150 mL

20.  Medulla Oblongata ◦ White matter contains sensory and motor tracts ◦ Contains nuclei  Cardiovascular center: reg. heart rate and force & diameter of blood vessels  Medullary rhythmicity area: controls breathing  Other nuclei control sensations of touch, pressure, vibration & reflexes for swallowing, coughing, vomitting, and sneezing

21.  Pons ◦ Above the medulla and anterior to cerebellum ◦ Consists of both nuclei and tracts ◦ Major function is its ability to connect areas of the brain  Rt. & lt. halves connect through pons  Connects sensory & motor tracts

22.  Midbrain ◦ Connects pons to diencephalon ◦ Anterior = cerebral peduncles  Conducts motor and sensory nerve impulses ◦ Nuclei of midbrain  Substantia nigra, red nucleus, sup. & inf. colliculi ◦ Reticular Formation  RAS (reticular activating system)  Consciousness  sleep

23.  Thalmus ◦ Relat station for sensory neurons ◦ Important in cognition ◦ Contributes to motor functions ◦ Contributes to reg. of ANS  Pineal Gland ◦ Size of a small pea ◦ Secretes melatonin  Controls biological clock  Promotes sleepiness

24.  Hypothalmus ◦ Most activities contribute to control of homeostasis ◦ ANS: heart rate, digestion, urinary bladder ◦ Pituitary gland – hormonal release ◦ Reg. emotion and behavior ◦ Reg. eating & drinking (thirst) ◦ Controls body temp. ◦ Patterns of wakefulness and sleep

25.  2 cerebellar hemispheres  Compares intended movements programmed by cerebral cortex w/ what is actually happening  Receives sensory impulses from muscles, tendons, joints, equilibrium receptors, visual receptors  Helps coordinate skeletal muscle contractions  Reg. posture & balance  Alcohol inhibits activity of cerebellum = ataxia

26.  Structure ◦ Folded gray matter = cortex  Gyri = folds  Fissures – deep grooves  Sulci – shallow grooves ◦ Corpus collasum connects two hemispheres ◦ Each half contains frontal, temporal, parietal & occipital lobes

27.  Functions ◦ Basal ganglia – initiate and terminate movements ◦ Sensory areas interpret sensory impulses ◦ Motor areas control muscular movement ◦ Association areas function in emotional and intellect ◦ Limbic system controls emotion and behaviors related to survival

28.  Sensory Areas – receive input  Motor Areas – respond to stimuli  Association Areas – deal w/ complex integrative functions ◦ Memory, emotions, reasoning, will, judgement, personality, intelligence

29.  Most sensory input received in the back of the brain  Primary sensory areas provide a direct link to PNS ◦ Primary Somatosensory Areas  Receive impulses of touch & feeling; can pinpoint origin of stimulus ◦ Primary Visual Area  Located on occipital lobe; interprets color, shape & movement ◦ Primary Auditory Area  Located on temporal lobe; hearing – pitch & rhythm

30.  Most motor output flows from anterior part of cerebral cortex  Primary Motor Areas ◦ Located in precentral gyrus in frontal lobes; controls voluntary muscle contraction on opp. sides of the body  Broca’s Speech Area ◦ Located on frontal lobe near lateral central sulcus; speaking & understanding language ◦ 97% of world population – language areas on left hemisphere

31.  Consist of motor and sensory areas  Somatosensory Assoc. Areas  Located post. to primary somatosensory area; integrates & interprets somatic sensations (exact shape & texture)  Visual Assoc. Areas  Located on occipital lobe; relates past & present visualization for recognizing and evaluating what is seen  Auditory Assoc. Area  Located below primary auditory area; allows person to recognize speech, music, or noise  Wernicke’s Area  Located in temporal & parietal lobes; interprets meaning of speech by recognizing spoken words (translates thoughts into words)  Adds emotion to spoken language  Common Integrative Area  Receives impulses from somatosensory area and interprets them  Premotor Area  Generates impulses that cause muscles to coordinate in a sequence (writing)  Frontal Eye Field Area  Control voluntary scanning movements

32.  Process by which information acquired through learning is stored & retrieved  For information to be committed to memory they must produce structural and functional changes in the brain  What parts are involved in MEMORY?  Association cortex of frontal, parietal, occipital & temporal lobes  Limbic system  Diencephalon

34.  12 pair  Part of the Peripheral Nervous System  Indicated using Roman Numeral (I, II, etc…) and Names  Roman Numerals indicate position from anterior to posterior  Names indicate distribution and/or function

40.  Aging  80 years of age brain weighs 7% less  Neuron # stays same, but # of synapses decline; conduction velocity decreases; voluntary motor movements slow down, reflex time increases  Parkinson’s  On average victims are 60 or older  Cause - unknown  Decrease in the release of the neurotransmitter dopamine  Symptoms - involuntary muscle contractions interfere with voluntary contraction & fixed facial expression  Alzheimer’s  Disabling senile dementia  Afflicts 11% of population over 65  Cause – genetic factors, environment & lifestyle, aging  Structural abnormalities  Neurons that liberate Ach  Clusters or plaques of proteins deposited outside neurons  Abnormal bundles of proteins inside neurons of affected areas of brain  Symptoms – loss of memory, forgetfulness, confusion