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Chapter 15-16 o tracts: bundles of nerve fibers in the CNS. Three types of tracts: - projection tracts- extend vertically between cerebrum & lower brain and spinal cord centers - commissural tracts o cross from one cerebral hemispheres to the other allowing communication...

Chapter 15-16 o tracts: bundles of nerve fibers in the CNS. Three types of tracts: - projection tracts- extend vertically between cerebrum & lower brain and spinal cord centers - commissural tracts o cross from one cerebral hemispheres to the other allowing communication between two sides of cerebrum o most pass through corpus callosum – cutting this (to treat severe epileptic seizures) can produce disconnection syndrome (each hemisphere aware of the other – hold item in left hand, can’t verbally state what it is - association tracts o connect different regions within the same cerebral hemisphere o long association fibers connect different lobes; short association fibers connect gyri within a lobe *Know that the limbic system consists of regions of the cerebrum AND diencephalon Language: o posterior speech area (Wernicke area): posterior to lateral sulcus, usually in left hemisphere; recognition of spoken & written language o motor language area (Broca area): inferior prefrontal cortex, usually in left hemisphere; generates motor program for the muscles of the larynx, tongue, cheeks, and lips for speaking and for hands when signing *Both are usually on the left hemisphere, W is sensory and B is motor *Disorder of either is called APHASIA: o aphasia: any language deficit from lesions in Wernicke, Broca areas (ex. nonfluent aphasia [approximate words, can’t say specific word but can say something similar to it]; fluent aphasia (make up words, gibberish)] Hemisphere differences: Left Hemisphere: - usually the categorical hemisphere - specialized for spoken and written language  - Sequential & analytical reasoning (math & science) o Breaks information into fragments & analyzes it Right Hemisphere: usually the representational hemisphere - Perceives information in a more integrated way - Seat of imagination & insight - Musical and artistic skill - Perception of patterns & spatial relationships Lateralization is correlated with handedness, age, and sex - Left hemisphere is categorical hemisphere in 96% of right-handed people & 70% of left-handed people - Lateralization develops with age; children more resilient to lesions on one side o Males exhibit more lateralization than females and suffer more functional loss when one hemisphere is damaged *Children who experience an injury can switch lateralization ECGS + GRAPHS! Four types of brain waves: - Alpha (𝜶) waves: 8-13 Hz o awake and resting with eyes closed and mind wandering o suppressed when eyes open or performing a mental task; also absent during deep sleep - Beta (𝜷) waves: 14-30 Hz o Accentuated during mental activity and sensory stimulation (higher frequency than alpha waves) o appear when awake and concentrating on something/performing a task - Theta (𝜽) waves: 4-7 Hz o found normally in children OR in intensely frustrated, drowsy, or sleeping adults (not a deep sleep) o may indicate a brain disorder or brain tumor in adults if not intensely frustrated, drowsy, or sleeping - Delta (𝛅) waves: less than 3.5 Hz o high amplitude o found in adults in deep sleep, in adults with brain damage (tumors, vascular blockage, or damage caused by inflammation of the brain) Nerve’s & #’s 1. Olfactory Nerves (I): sensory function (smell) 2. Optic Nerves (II): sensory function (vision) 3. Oculomotor Nerves (III): motor function (eye movement, iris) 4. Trochlear Nerves (IV): motor function (eye movement) 5. Trigeminal Nerves (V): sensory (face, mouth) and motor (mouth) 6. Abducens Nerves (VI): motor function (eye movement) 7. Facial Nerves (VII): sensory (taste) and motor function (facial expressions) 8. Vestibulocochlear Nerves (VIII): sensory function (hearing, balance/equilibrium) 9. Glossopharyngeal Nerves (IX): sensory (taste) and motor function (head & neck) 10. Vagus Nerves (X): sensory (viscera) and motor (digestive, respiratory) 11. Accessory Nerves (XI): motor function (neck, upper back) 12. Hypoglossal Nerves (XII): motor function (tongue movement) Mnemonic: Odor Of Orangutan Terrified Tarzan After Forty Voracious Gorillas Viciously Attacked Him Chapter 17 Spinal segment: part of spinal cord supplied by each pair of spinal nerves Surface Anatomy: - Two areas of the cord are thicker than elsewhere: o Cervical enlargement (around C6) – gives rise to nerves of upper limb o Lumbosacral enlargement (around T11) – gives rise to nerves of pelvic region, lower limbs Epidural space: - Epidural space – space between dura and vertebral bones; contains blood vessels, adipose tissue, loose connective tissue o Anesthetics can be introduced into epidural space (epidural anesthesia/ epidural block) – temporary sensory block and some possible motor paralysis used commonly at the inferior lumbar/sacral region for pain control during childbirth. Only affects the spinal nerves in the immediate area. Why is spinal tap performed around L3-4 or L4-L5? So, you do not hit the spinal cord Know the difference between Coccygeal and Denticulate ligaments - Delicate, transparent membrane that follows contours of spinal cord and continues inferiorly as a fibrous terminal filum which then fuses with dura to form coccygeal ligament – anchors the spinal cord to prevent longitudinal (up/down) movement - Denticulate ligaments – extensions of pia that pass-through arachnoid to the dura, anchoring cord to stabilize it from lateral (side-to-side) movements *coccygeal = longitudinal, denticulate= lateral Cross sectional anatomy Spinal cord has gray matter and white matter - Gray matter – dull in color (no myelin); contains neuron cell bodies, dendrites, and proximal portions of axons. Appears as a butterfly shape in a transverse section of the spinal cord. - White matter – bright, pearly white color due to myelin; axon bundles coursing up and down cord. White matter surrounds gray matter. White matter – surrounds the gray matter of the spinal cord Three large bundles of axons in the white matter: 1. Posterior white column/funiculus – proprioception, fine touch, ventral pressure, vibrations 2. Anterior white column/funiculus – crude touch and pressure, somatic motor 3. Lateral white column/funiculus – proprioception, somatic motor - In between posterior and anterior funiculus - Each funiculus subdivided into fasciculi or tracts *Know which one is crude touch and which one is fine touch o Poliomyelitis – caused by the poliovirus; the virus spreads by fecal contamination of water - Destroys motor neurons in brainstem and anterior horn of spinal cord - Signs/symptoms of polio include muscle pain, weakness, and loss of some reflexes o Followed by paralysis, muscular atrophy, and respiratory arrest - Treatment: no cure/specific treatment; vaccine available to prevent polio *As motor neurons die the skeletal muscles stop receiving information and shrivel up and die Amyotrophic lateral sclerosis (ALS) or Lou Gehrig disease – 10% of cases caused by inheritable genetic mutation, rest of the cases are of unknown cause. The disease causes the destruction of motor neurons and muscular atrophy - Astrocytes fail to reabsorb the neurotransmitter glutamate from the tissue fluid which accumulates to toxic levels - Early signs: muscular weakness; difficulty speaking, swallowing, and using hands; sensory and intellectual functions remain unaffected Spinal Nerves There are 31 pairs of spinal nerves: 8 cervical (C1 to C8) o First cervical nerve exits between skull and atlas (C1) o Others exit at intervertebral foramina between adjacent vertebrae 12 thoracic (T1 to T12) 5 lumbar (L1 to L5) 5 sacral (S1 to S5) 1 coccygeal (Co1) *Know the #’s!!! ^^^ Nerve Plexuses Anterior rami branch and anastomose/”interlink” repeatedly to form five nerve plexuses: 1. Cervical plexus in the neck, C1 to C5: supplies neck and phrenic nerves to the diaphragm Major nerve - Phrenic nerve (C3-5) – controls diaphragm. Damage to this nerve can cause you to stop breathing. Other branches of this nerve innervate skin of neck and superior chest o “C3-5 KEEPS YOU ALIVE” 2. Brachial plexus near the shoulder, C5 to T1: supplies upper limb and some of shoulder and neck - Divided into roots, trunks, divisions, and cords. Major nerves include: - Musculocutaneous nerve – flex arm, receives sensory info on lateral surface of forearm - Radial nerve – extensor muscles of arm & forearm, receives sensory info from posterolateral surface - Median nerve – flex forearm, receives sensory info from anterolateral hand - Ulnar nerve – flex hand, receives sensory info from medial surface of hand - Axillary nerve – deltoid muscle for abduction of arm 3. Lumbar plexus in the lower back, L1 to L4: supplies abdominal wall, anterior thigh, and genitalia - Major nerves include the femoral nerve – serves medial and anterior compartment of leg 4. Sacral plexus in the pelvis, L4, L5, and S1-S4: supplies remainder of lower trunk and lower limb, including sciatic nerve - Two branches of the sciatic nerve: 1. Fibular nerve – sural nerve formed from fibular nerve innervates lateral portion of foot (part of this nerve used in nerve grafts) 2. Tibial nerve – serves the foot *For lumbar plexus only need to know femoral nerve *For sacral plexus know fibular & tibular nerve Nerve injuries Radial nerve injury: - Nerve passes through axilla, may be compressed by crutches – crutch paralysis - Wrist drop – fingers, hand, wrist chronically flexed because extensor muscles paralyzed and cannot oppose the flexors Sciatic nerve injury - Sciatica – sharp pain that travels from gluteal region along the posterior side of the thigh and leg to ankle - 90% of cases result from herniated intervertebral disc or osteoarthritis of lower spine Lesson 18 Visceral reflexes (autonomic reflexes) - Control systems other than muscular system o Ex: Smooth and cardiac muscles, glands, adipose tissue Spinal Reflexes o Monosynaptic reflexes – fastest, least complex o Polysynaptic reflexes- more complex & slower o Intersegmental reflex arcs- slowest & most complex Stretch (myotatic) reflex – when a muscle is stretched, it “fights back” and contracts - Maintains balance, pulls body back Structure of a muscle spindle: Intrafusal fibers – modified muscle fibers within the spindle - The rest of the muscle’s fibers (those generating force for movement) are extrafusal fibers - A gamma motor neuron (located in anterior gray horn of spinal cord) innervates the ends of an intrafusal fiber and keeps it taut – allows CNS to adjust sensitivity of the muscle spindle – allows voluntary contraction to NOT trigger the reflex. Note: the alpha motor neurons supply the extrafusal fibers The midportion of the intrafusal fiber contains sensory nerve fibers - The primary afferent fibers monitor fiber length and speed of length changes while the secondary afferent fibers – monitor length only - Example of spindle function: help you to keep upright when standing on a boat (postural reflex – a type of stretch reflex) *Need to know the difference between gamma motor neurons and alpha motor neurons Polysynaptic reflex arc – pathway in which signals travel over many synapses on their way to the muscle *At least one interneuron between sensory and motor neuron, more than one synapse Five General Characteristics of Polysynaptic reflexes: 1. Involve pools of interneurons – tendon reflex inhibits motor neurons while flexor and crossed extensor reflexes controls which muscles contract 2. Involve reciprocal inhibition 3. Have reverberating circuits – prolongs reflexive motor response after initial stimulation is gone 4. Are intersegmental in distribution (more than 1 spinal segment involved) 5. Several reflexes cooperate – to produce coordinated, controlled response The Crossed Extension Reflex - Flexor reflex uses an ipsilateral reflex arc, (stimulus and response are on the same side of the body) whereas crossed extension reflex uses a contralateral reflex arc (input and output are on opposite sides of the body) Reinforcement of Spinal Reflexes can occur Ex: Jendrassik maneuver – hooks fingers together and try to pull hands apart. Reinforces knee jerk reflex when patellar ligament is tapped and stretched. *Need to know how it is applied and why it is used: - upper extremities: clench teeth, squeeze teeth - Prevents you from inhibiting stretch reflex Babinski Reflexes - Positive Babinski reflex normally displayed by infants (myelination of spinal tracts not complete) – fanning of toes when medial side of sole is stimulated. Fanning of the toes is known as displaying the Babinski sign. If displayed in adults, it may indicate CNS damage - Negative Babinski reflex - seen in normal adults. When stimulated, curling of toes (plantar reflex) occurs Types of neural circuits:  - Diverging circuit – one nerve fiber branches and synapses with several postsynaptic cells. Ex: Visual info goes to visual cortex and postural/balance areas - Converging circuit – input from many different nerve fibers can be funneled to one neuron or neural pool. Ex: Subconscious and conscious control of breathing - Reverberating circuit – positive feedback; neurons stimulate each other in linear sequence but one or more of the later cells restimulates the first cell to start the process all over. Ex: cross extension reflex - Parallel after-discharge circuit – input neuron diverges to stimulate several chains of neurons o Neuron chains with different number of synapses converge on one or a few output neurons, but with varying delays o After-discharge – continued firing after the stimulus stops. Ex: stare at bright light, close eyes and still see it *Know ALL the examples^^^^ Serial processing- one singular pathway Parallel processing- multiple pathways Lesson 19 Autonomic nervous system, ANS (visceral motor system) – a motor nervous system that controls glands, cardiac muscle, and smooth muscle - Primary target organs of the ANS: o Viscera of thoracic and abdominal cavities o Some structures of the body wall – cutaneous blood vessels, sweat glands, o and arrector muscles *Visceral reflexes are similar to somatic reflexes but in visceral reflexes the receptors are found internally Autonomic tone – normal background rate of activity that represents the balance of the two systems according to the body’s needs Examples of parasympathetic tone:  - Maintains smooth muscle tone in intestines - Holds resting heart rate down to about 70 to 80 beats per minute Example of sympathetic tone: - Keeps most blood vessels partially constricted and maintains blood pressure Neither division has universally excitatory nor inhibitory effects; usually the two divisions have opposing effects *KNOW difference between two tones Sympathetic division - Cell bodies of preganglionic neurons in lateral gray horns of spinal cord ****Seven Responses to Increased Sympathetic Activity 1. Heightened mental alertness 2. Increased metabolic rate 3. Reduced digestive and urinary functions 4. Energy reserves activated 5. Increased respiratory rate and respiratory passageways dilate 6. Increased heart rate and blood pressure 7. Sweat glands activated Sympathetic Chain Ganglia Control effectors: - In body wall - Inside thoracic cavity - In head - In limbs Adrenal medulla – inner core; essentially a sympathetic ganglion - Secretes a mixture of hormones into bloodstream: the catecholamines – 85% epinephrine (adrenaline) and 15% norepinephrine (noradrenaline) Adrenergic- NE Cholinergic- Ach Pathway of parasympathetic division - Preganglionic fibers travel through cranial or sacral nerves, end in terminal ganglia in or near target organs (intramural ganglion – embedded within organ wall) *Know the difference ^^^ (also most parasympathetic output happens in vagus nerve) Five Responses to Increased Parasympathetic Activity 1. Decreased metabolic rate 2. Decreased heart rate and blood pressure 3. Increased secretion by salivary and digestive glands 4. Increased motility (movement of material in digestive tract) and blood flow in digestive tract 5. Stimulation of urination and defecation Two categories of cholinergic (ACh) receptors: ****KNOW THE DIFFERENCE Muscarinic receptors – found on cardiac muscle, smooth muscle, and gland cells with cholinergic innervation - Act through second-messenger systems - Receptor subtypes exist, often providing contrasting effects on organs - Example: ACh excites intestinal smooth muscle, but inhibits cardiac muscle  Nicotinic receptors – found on ganglionic neuron cell bodies in autonomic ganglia; on cells of adrenal medulla; and neuromuscular junction of skeletal muscle fibers - Binding of ACh to these receptors is always excitatory - Open ligand-gated Na+ ion channels, produce excitatory postsynaptic potential Nicotine – KNOW THAT 50MG IS TOXIC & SIGNS & SYMPTOMS OF BOTH - Binds to nicotinic receptors in sympathetic and parasympathetic ganglion cells - Targets autonomic ganglia and skeletal neuromuscular junctions - 50 mg ingested or absorbed through skin causes poisoning - Signs and symptoms: o Vomiting, diarrhea, high blood pressure, rapid heart rate (tachycardia), sweating, profuse salivation, convulsions - May result in coma or death Muscarine – toxin produced from some poisonous mushrooms - Binds to muscarinic receptors - Targets parasympathetic neuromuscular or neuroglandular junctions - Signs and symptoms: o Salivation, nausea, vomiting, diarrhea, constriction of respiratory passages, low blood pressure, slow heart rate (bradycardia) *Beta and alpha-adrenergic receptors both use second messengers Alpha 1- has EXCITATORY effect on target cell Alpha 2- has INHIBITORY effect on cell Three Main Types of Beta Receptors 1. Beta-1 ( 1): Increases metabolic activity – increase activity of skeletal and cardiac muscle 2. Beta-2 ( 2): Triggers relaxation of smooth muscles along respiratory tract – increases diameter of air passages 3. Beta-3 ( 3): Leads to lipolysis, the breakdown of triglycerides in adipocytes – releases nutrients into bloodstream Autonomic effects on glandular secretion are often an indirect result of their effect on blood vessels Increased blood flow, increased secretion Decreased blood flow, decreased secretion Some ANS fibers release other neurotransmitters in addition to ACh or NE Examples: enkephalin, substance P, neuropeptide Y, somatostatin, neurotensin, gonadotropin-releasing hormone, nitric oxide (NO) *EX ?- “which of these NT can be released by ANS in addition to ACh & NE ^^^^ Control Without Dual Innervation Some effectors receive only sympathetic fibers - Adrenal medulla, arrector muscles, sweat glands, many blood vessels Lesson 20 Skeletal – voluntary Cardiac- involuntary Smooth- involuntary *Both smooth & skeletal CANNOT regenerate Universal Characteristics of Muscle All muscle cells have the following characteristics:  - Excitability (responsiveness) – to chemical signals, stretch, and electricalchanges across the plasma membrane - Conductivity – local electrical excitation sets off a wave of excitation that travels along the muscle fiber - Contractility – shortens when stimulated - Extensibility – capable of being stretched between contractions - Elasticity – returns to its original rest length after being stretched Skeletal muscles are the LONGEST - Skeletal muscle cells also called muscle fibers or myofibers ****Six functions of skeletal muscle tissue: 1. Produce skeletal movement – voluntary control through the somatic nervous system (SNS) 2. Maintain posture and body position 3. Support soft tissues – line abdominal wall and pelvic cavity 4. Guard entrances and exits – Ex: sphincters in alimentary canal, urethra 5. Maintain body temperature – Ex: contractions (shivering) produce heat 6. Store nutrients reserves – muscle protein breaks down when nutrients needed Endomysium - Contains myosatellite cells (stem cells) that repair damage to muscle cells – minimal repair ability, cannot develop into a whole muscle cell to replace a dead muscle cell