Brain & Cranial Nerves (PDF)

Brain & Cranial Nerves The Human Brain 4 major brain regions:. Cerebrum : 1 2 hemispheres ; 5 lobes per hemisphere 2 Diencephalon : organized....

Brain & Cranial Nerves The Human Brain 4 major brain regions:. Cerebrum : 1 2 hemispheres ; 5 lobes per hemisphere 2 Diencephalon : organized. in to epithalamus , thalamus, & hypothalamus. Brainstern : has midbrain 3 + , pons , medulla oblongata 4. Cerebellum Diencephalon # identify on diagram. · outlined in purple. · encloses the 3rd the Ventricle+ connects - hemispheres to cerebral # - 3 - he brainstemm - · its main subdivisions are outlined in BOLD  Cerebellum coordinates & fine-tunes movements ensures muscle activity follows correct pattern · stores memories of previously learned movements · regulates activity along voluntary& involuntary motor paths adjusts movements initiated by cerebrum ensuring · , smoothness helps equilibrium posture · maintain ↳ receives proprioceptive info from muscles joints -continuously receives motor plans & Sensory Feedback > ↳ be sent to may generate error-correcting signals to premotor & primary motor cortex Cerebral Hemispheres. Cerebrum composed of left ↓ right hemispheres · longitudinal fissure : deep cleft separating hemispheres · At a few locations white matter tracts connect the hemispheres ↳ Corpus collosum : providing largest tract connection between them of cerebrum exhibit multiple functions regions may · some easily assigned to 7 region not. · connections with body are crossed ↳ left hemisphere signals from receives sensory right side of body + sends motor signals to right side of body  Thalamus · relay station of brain oval masses of matter on lateral sides of third Ventricle gray · · composed of about a dozen of thalamic nuclei except Olfaction ~ receives signals from all conscious senses ↳ relays some Signals to appropriate part of cortex ↓ filters out Signals other distracting from subject of attention (eX : background noise) Hypothalamus · Antero inferior region of diencephalon · infundibulum : Stalks of pituitary that extend from hypothalamus Functions of Hypothalamus: Control · of Autonomic NS : influence heart rate , blood pressure, digestive activities , respiration Control endocrine systems: Secrete hormones that · control activities in anterior pituitary gland · produce antidiuretic hormone & Oxytocin. · Regulation of Body temp: Neurons in preoptic area detect altered temp signal other hypothalamic nuclei to heat cool body · or · Food Intake : Ventromedial nucleus monitors nutrient levels , regulates hunger Water intake : · Anterior nucleus monitors conc of dissolved substances in blood regulates thirst ↳ · sleep-wake rhythms : Suprachiasmatic nucleus directs pineal gland to secrete Melatonin , regulates Circadian rhythms ~ Emotional behaviour : part of limbic system , controls emotional response.  Brainstem · connects cerebrum , diencephalon , + Cerebellum to spinal cord · contains ascending descending tracts · contains autonomic nuclei , nuclei of cranial nerves , a reflex centers Consists · of Midbrain , pons , t medulla oblongata. - Pons & Medulla Oblongata Pons : Sensory& motor tracts located within extend through it brain & to connect Spinal cord. contains respiratory centers that regulate Skeletal Muscles of breathing. (Autonomic) I heart rate Medulla Oblongata - Autonomic nuclei control : Cardiac Center regulate heart output - Vasomotor Center blood Vessel diameter regulate - ↳ strong influence of blood pressure Medulla respiratory Center - Controls breathing rate · contains dorsal + ventral respiratory groups Communicates W. pontine respiratory Center · · coughing , sneezing vomiting, salivating swallowing , ,  Functional areas of cortex Frontal lobe: Primary motor cortex premotor cortex · · Frontal eye field · prefrontal cortex. · motor speech(broca area) area Parietal lobe : primary somatosensory cortex (in post central gyrus · somatosensory association area occipital lobe : Primary Visual Cortex · Visual association arta Temporal lobe : Primary Auditory cortex · Auditory association area primary olfactory cortex responsible for wernicks area understanding spoken - written language.  Cranial Meninges 3 · connective tissue layers · separate d support soft tissue of brain enclose + protect blood vessels supplying the brain help contain& circulate Cerebrospinal Fluid Spiderless · from deep to superficial P A D.. ↳ same layers in Spinal cord 1. Piamater softt delicate - 1. Arachnoid mater-like. 3 Dura mater - tough layer · composed of 2 layers cerebrospinal fluid. ↳ & periosteal laye v ependymal makes cerebrospinal fluid meningial layer · Cerebrospinal Fluid · clear colourless liquid surrounding CNS · circulates in Ventricles & subarachnoid space · Functions : · Buoyancy - reduces brains apparent weight by 95 % · protection - provides a liquid cushion -- · Environmental Stability Transport of nutrients/wastes + protects against fluctuations. · produced in choroid Plexus in Ventricles ↳ choroid plexus composed of ependymal cells  Cerebral white matterTracts · Association , commissural , I projection tracts · Association Tracts : connect diff. regions of the cerebral cortex within same hemisphere ↳ ex : tract that connects the cortex with premotor motor cortex (both Frontal lobe). primary in. · the longer association tracts , called the longitudinal fasciculi connect gyri in diff lobes of same hemisphere. ) ex : ↳ tract that connects the Wernicke area to motor Speech area- Commissural Tracts : extend between cerebral hemispheres through axonal bridges called commissures · the prominent commissural tracts that link left right cerebral hemispheres include large C-shaped , corpus collosum+ smaller anterior + posterior commissure. tracts : link cerebral to both the inferior brain Projection the cortex regions ~ Spinal cord. ↳ ex: corticospinal tracts that transmit motor signals from cerebrum to brain stemof Spinal Lord. & Identify - describe function of cerebral cortex areas un & for larger more precise movements Primary Motor Cortex · motor areas are housed within frontal lobes. · Primary motor cortex : located in precentral gyrus in frontal lobe. also called Somatic · motor area Controls Skeletal · Muscle activity on opposite side of body project contralaterally (opposite side) ↳ within brainstem or Spinal cord the controlled homunculus body regions as a motor · map ↳ the distorted proportions of the body reflect the amount of cortex dedicated to each part ↳ ex : homunculus be large brain hands are large on area of controls their precise movements ↳ fine motor movements · Motor speech area : also known as Broca area. · located in inferolateral portion of left frontal lobe · controls movement for vocalization · Frontal eye field : Within frontal lobe superior to motor speech area. ↳ superior surface of middle front gyrus regulates needed for reading binocular Visi · eye movements · Premotor cortex also called somatic motor association area frontal lobe to anterior precentral gyrus. · · responsible for coordinating learned , skilled motor activities.  Primary Somatosensory Cortex areas within parietal temporal d occipital · , , lobes & insula are involved in conscious awareness of sensation n. · Primary Somatosensory cortex : housed within postcentral gyrus of parietal lobes · receives , processes a storesSomatic sensory information ↳ touch , pressure , pain , I temp receptors also proprioceptors from joints & muscles regarding the conscious interpretation of body position. · Areas of body sending input can be mapped as sensory homunculus ↳ distorted proportions reflect the amount of sensory information collected from that region large regions for lips fingers + genital region) ↳ , , Somatosensory Association area : located in parietal lobe immediately posterior to post central gyrus · integrates touch info allowing us to identify objects by feel Primary Visual Cortex : located within occipital lobe Visual association area ! Surrounds primary Visual Cortex · integrates colour , form , memory for us to identify things (faces Primary Audio cortex : located within temporal lobe. Auditory Association area : located in temporal lobe interprets sounds; · stores + retrieves memories of sound Primary of factory complex : located within temporal lope · provides conscious awareness of smells Primary gustatory cortex : located within insula involved in processing taste information ·  Cranial Nerves · 12 pairs of Cranial nerves Part of PNS from brain originating ~ Roman numerals · name often related to function nose eyes Balance I hearing - down clook muscle of eye. upper oblique Abduct eye - shrugging - motor aspect of tongue. 3 face muscles muscles artund eye. facial expressions + anterior tongue swallowing & glossus sensory ~ 90 % of Parasympathetic vi-forehead tion 7 - T - Wesse # ~ - EVE num Ve-cheekbones anterior aspect of X - 90% of Parasympathetic tongue motpet swallowing sensory to glossus. rang # V3-mandible/jaw. shrugging 2  Spinal Nerve Plexuses Spinal Cord & Spinal Nerves Major functions of Spinal cordo Spinal Nerves : 1 Structural &functional link between brain t. rest of body from body commands from brain sensory input · , motor 2. Spinal reflexes responses that don't brain ~ involve · fast reaction to stimulus Nerve = Cable - like bundle of axons. Connective tissue : wrappings EPineurium (around nerve · · perineurium (around Fascicle) Endonurium (around axon) · 31 pairs of spinal nerves ↳ names begin w first letter of spinal Lord region to which it attaches / followed by a number. J 3 · head, neck , shoulders. Cervical - 7 bones & Nerves phrenic nerve t diaph. · Thoracic - 12 bones + 12 Nerves · Chest shoulders S , , Lumbar - S bones & nerves arms for arms, hands sacral - - bones & & Nerves , radial , ulnar , median · coccyx-1 bone I Nerve nerves. = 3) spinal nerves. · abdomen , back , groin , thighs knees , caves · Femoral + obturator nerves · pelvis , buttocks , genitals, thighs , calies , a feet. · sciatic nerve.  Upper Limb Median nerve injury - may be compressed in carpal funnel syndrome · causes paralysis to thenar muscles , lateral lumbricals ; anesthesia in part of han. Unar nerve injury may be injured by Fractures of dislocation - of elbow · cause paralysis of most intrinsic hand ; medial hand. muscles sensory loss on Superior (CS-C6) of trunk injury injured by excessive separation - neck ↓ shoulder branch any brachial plexus · that has these nerves affected Inferior trunk (C8-TD injury - can be injured if arm is excessively abducted any brachial plexus branch these - from affected to some nerves are degree.  Anterior Lower Limb Spinal -14 · nerves · femoral nerve : innervates anterior thigh muscles like quadraceps femors (knee extensor) ↓ sartorius , psoas J iliacs Chip flexors , · obturator nerve : innervates medial thigh Muscles (adduct thigh Posterior Lower Limb. superior inferior gluteal nerves can be injured by poorly · or : placed gluteal injection. Scratica : to sciatic nerve injury · extreme pain down posterior thigh f les - herniated intervertebral dis · splits in to tibia a fibula nerve  Spinal roots & Spinal Nerves Sensory receptors : Somatic (tactile receptors proprioceptors) , Visceral (baroreceptors chemo receptors) , Effectors : Somatic (skeletal muscles Visceral (autonomic e. g Cardiac muscle , smooth muscle d glands) spinal neve gross anatomy : · rooflets merge to form roots mixed posterior root contains sensory ↑ - neurons+ posterior root ganglion contains cell bodies of these neurons · Anterior root contain motor neurons · each spinal nerve forms where the roots join · sensory + motor neurons in each spinal nerve so they are classified as mixed nerve. Cross Section of Vertebra + Spinal Cord · Spinal cord is collectively protected by a bone structure , meninges , ↓ Cerebrospinal flaid like the brain. , just vertebral column houses the Spinal cord. ↳ spinal cord passes through Vertebral Canal ↳ foramen. each spiral nerve exits through an intervertebral  Cross Section oSpinal Cord & Spinal Roots Gray matter: made of neuron's zell bodies , dendrites , & unmyelinated also cells axons ; glial Masses of gray matter project from Center of Spinal cood: cell bodies posterior horns: house axons of sensory neurons + of interneurons Anterior horns : house cell bodies of somatic motor neurons Lateral horns : house cell bodies of autonomic motor neuron) · only present in parts T. - 12 Gray Commissure - horizontal band of gray matter that surrounds central canal unmyelinated left & right contains axons connecting · grayMatter : Nuclei groups of cell bodies posterior horn interneurons sensory nuclei: in contains Somatic Sensory nuclei - receive Signals from Skin , muscle , joints Visceral Sensory nuclei-receive from blood vessels , Viscera signals Motor nuclei - Anterior + lateral horns contain motor neurons Somatic Motor nuclei -Anterior ; innervate skeletal musche Visceral motor nuclei - lateral ; innervates smooth muscle, hearts , glands White matter : myelinated axons toa from brain white matter : Regions of posterior funiculus : Contain sensory tracts Laxon bundles caled fasciculi Lateral funiculus : contains sensory (ascending) ↓ motor /descending) tracts Anterior funiculus! tracts - contains sensory + motor  Steps of Reflex Arc. 1. Stimulus activates receptor Nerve 2. Signal is propagated through sensory neuron to the spinal cord. 3 Nerve Signal is processed in integration center by interneurons 4. Nerve Signal is propagated by motor neuron effector. 5 Effector responds Classifying Spinal Reflexes · Spinal or cranial - is spinal cord or brain the reflex integration center · somatic or Visceral - is effector skeletal muscle or cardiac , smooth , or a gland ? · Monosynaptic or Polysynaptic - Do sensory neurons synapse directlyw motor neurons or are there interneurons in the reflex ar < · ipsilater or Contralateral - Are receptors & effectors on same side of body or opposite · innate or acquired - boon w reflex or developed later ?  Monosynaptic & Polysynaptic Reflexes Stretch Reflex'. Reflexive contraction of a muscle after it is stretched ~ stretch is detected by a muscle spindle propriocepto · when stretched Spindle's fires impulse ; sensory axon that are conducted to spinal cord in Spinal cord sensory axon excites alpha motor · , neurons of the same muscle contracti , causing (monosynaptic) · Simultaneously , the sensory axon excites interneuro that inhibit motor neurons of antagonist muscle (polysynaptic reciprocal inhibition ( Stretch classified as : Spinal , somatic , monosynaptic , ipsilateral, innate  Spino-cerebellar Pathway · from spine to cerebellum. (Ascending of uses chain only 2 neurons to communicate w brain about · a specific stimulus in proprioceptors. this input provides info to the brain related to sensory subconscious postural output (balance d posture) recall that the posterior funiculus medial lemniscal pathway · - transmits proprioceptive info for Conscious interpretation. Primary Neuron extends from to Spinal cord · proprioceptor in - ViaPosterior root. primary neuron synapses secondary · to Within horn of spinal cood posterior · Secondary Neuron-extends from spinal cord within spinocerebekar tract Within either the anterior or posterior portion of lateral funiculus to theLerebellum- Corticospinal Tracts (Descending) from cerebral cortex to spin. descending · · Motor pathways that control effectors (skeletal muscles - 2 motor neurons present within pathways ~ upper motor neuron : 1st neuron in chain · housed within Cerebral cortex , Cerebral nuclei, or specific nucleus within brainstern. (in direct synapse directly upon lower motor neurons pathways ~ lower motor neuron ! last neuron in chain. housed within cranial nerve nucleus or anterior horn spinal cord · exit the spinal axons cord through anterior root · always excitesSkeletal Muscle Fibers to contract  Spinal Lord ↓ Spinal Nerve Receptors : Mechanoreceptor respond to mechanical stimuli of proprioceptors type mechanoreceptor ~ are a - Thermoreceptor : lemp changes Nociceptors : process pain t temp photoreceptors : Sensitive to light chemoreceptors : change in chemical composition of blood.