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32 Cards in this Set
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What does the Central Nervous System consist of? |
The Brain and Spinal Cord |
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What does the Peripheral Nervous System consist of? |
1.) Cranial Nerves: 12 pairs from the brain 2.) Spinal Nerves: 31 pairs from the spinal cord |
2 different nerves |
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How many divisions does the PNS have and what divides them? |
They are divided into two groups : 1.) Sensory (afferent) fibers: receive stimulus; sends impulse to the CNS. 2.) Motor (efferent) fibers: transmit impulses from the CNS; impulses to effector (muscle or gland); the effector produces a response *They are divided based upon their functions of their nerve fibers . |
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What are the divisions of motor fibers & how many groups are they classified in? |
*They are classified into two groups: 1.) Somatic motor system: motor fibers to voluntary effectors (e.g. skeletal muscles) 2.) Autonomic motor system: motor fibers to involuntary effectors (e.g. smooth and cardiac muscle, and glands) |
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Divisions of Autonomic Nervous System |
1. Parasympathetic Nervous System (Craniosacral Division): the "resting & digesting" division; short postganglionic fibers release acetylcholine (ACh) as a neurotransmitter to elicit a relaxed, calm state -Long preganglionic fibers arise from cranial and sacral spinal nerves (i.e. "craniosacral" division) 2. Sympathetic Nervous System (Thoracolumbar Division): The "fight or flight" division;long postganglionic fibers release norepinephrine (NE) as a neurotransmitter to elicit a excited, high energy state -Short preganglionic fibers arise from thoracic and lumbar spinal nerves (i.e. "thoreacolumbar" division) |
Further divided based upon the actions of the effectors. |
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Central Nervous System: The Brain |
· The Brain is the enlarged anterior end (superior in humans) of the central nervous system protected by bony armament, the skull. ·The evolution of the brain is the result of cephalization (i.e. the formation of a head) · In comparison to the remainder of the nervous system, the brain contains a disproportionate number of neurons, ~ 100 billion. |
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Brain Embryology |
· Brain development begins in about 3 weeks from ectoderm ·By the 4th week, a portion of the ectoderm (neural plate) invaginates to form the neural tube. ·By the 5th week, the rostal end of the neural tube forms three "primary brain vesicles": -Prosencephalon: "forebrain" -Mesencephalon: "midbrain" -Rhombencephalon: "hindbrain" --The causal end of the neural tube, beyond the rhombencephalon, becomes the spinal cord. ·After the 5th week, five "secondary brain vesicles" develop from the primary.. -Prosencephalon: ·Telencephalon [end brain] · Diencephalon [between brain] -Mesencephalon (forms nothing new; becomes larger) -Rhombencephalon ·Metencephalon [after brain] ·Myelencephalon [spinal brain] ·From the secondary brain vesicles, the four "primary brain regions" develop: -Telencephalon --> "Cerebrum" -Diencephalon --> remains "Diencephalon" -Mesencephalon --> (in part) -Metencephalon --> "brainstem" (in part) & "Cerebellum" -Myelencephalon --> "brainstem" (in part) |
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What are the four primary regions of the brain? |
1. Cerebrum (cerebral hemispheres) 2. Diencephalon 3. Brainstem 4. Cerebellum [little brain] |
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About The Cerebrum (cerebral hemispheres) |
·It is the most superior and massive portion of the brain. ·~83% of the total brain mass. · Highly convoluted with shallow sulci (son, sulcus) and deep fissures. ·Ridges between sulci are called gyri (sin, gyrus). |
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Divisions of the Cerebrum |
·The cerebrum is divided into two cerebral hemispheres by the longitudinal fissure. ·Both hemispheres are separated from the cerebellum by the transverse fissure. |
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Lobes of the Cerebrum |
·Each hemp is divided by fissures and sulci into five anatomically and functionally distinct lobes: 1.Frontal lobe: anterior to the central sulcus 2. Parietal lobe: between the central sulcus & parieto-occipital sulcus 3. Occipital lobe: posterior to the parieto-occipital sulcus 4. Temporal lobe: inferior to the lateral sulcus 5. Insula (Island of Reil): within the lateral sulcus |
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Functional Regions of the Cerebrum |
Like most of the CNS, the cerebrum contains myelinated & unmyelinated axons. Myelinated areas constitutes "white matter" & unmyelinated "gray matter". 1. Cerebral cortex: superficial layer,~ 1/8 "thick, gray matter; area of conscious thought and higher brain functions 2. Cerebral medulla: inner white matter forming the bulk of the cerebrum, provides communication pathways between the cortex and other brain areas. 3. Basal nuclei: caudate nucleus, putamen & globus pallidus; regions of gray matter deep within the medulla; serve in muscle coordination |
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About The Diencephalon |
· Gray matter forming the central core of brain between the cerebral hemispheres; divided into three regions: 1. Thalamus: ~80% of diencephalon forming the lateral walls of third ventricle; relays information to the cerebral cortex from several diverse regions of the brain; information from every sensory system (except olfaction) synapse here before reaching the cerebral cortex; serves as a "switchboard" for the brain 2. Hypothalamus [below thalamus]: anterior-inferior extension of thalamus supporting the pituitary gland; functionally, the hypothalamus is responsible for many homeostatic activities (e.g. blood pressure, body temperature, fluid and electrolyte balance, and body weight) 3. Epithalamus [above thalamus]: dorsal-posterior covering of diencephalon supporting the pineal [little pinecones] gland (epiphysis cerebri or "third eye") which produces melatonin, and the choroid plexus which produces cerebrospinal fluid |
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What are the three regions the Diencephalon is divided into? |
1. Thalamus 2. Hypothalamus 3. Epithalamus |
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About The Brainstem |
Inferior portion of brain; joins spinal cord; three regions: 1. Midbrain: develops from the embryonic mesencephalon connecting the hindbrain and the forebrain; major regions of the midbrain: -Cerebral peduncles: spinal tracts to the medulla oblongata -Corpora quadrigemina [quadrupled bodies]: A pair of superior colliculi [hills] for visual reflexes, and a pair of inferior colliculi for auditory reflexes 2. Pins [bridge]: from embryonic metencephalon; contains nuclei concerned with sleep, posture, respiration, swallowing, and bladder control 3. Medulla oblongata: from embryonic mylencephalon; contains nuclei to control heart rate, vasoconstriction, breathing rate, coughing, sneezing, hiccuping, sweating, vomiting, and other functions |
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What are the three regions of the Brain stem? |
1. Midbrain 2. Pons 3. Medulla |
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About The Cerebellum [little brain] |
·From embryonic metencephalon; consists of right and left cerebellar hemispheres connected by a dermis ·Modulates and coordinates voluntary movement of the limbs, maintains muscle tone and posture, coordinates eye movements, and helps in learning motor skills |
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Protection of Brain & Spinal Cord |
Three primary structures protect the CNS: bone, menings , & cerebrospinal fluid (CSF) |
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What are the three connective tissue membranes that make the meninges? |
1. Dura Mater [tough mother] 2. Arachnoid Mater [spider mother] 3. Pia Mater [gentle mother] |
The meninges are three connective tissue membranes that separate the brain & spinal cord from the skull and vertebrae |
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About The Arachnoid Mater [spider mother] |
· Middle meninx; seperated from the dura mater with serious fluid in the super subdural space ·Deep to the arachnoid mater is the subarachnoid space filled with CSF · Arachnoid fibers, located in the subarachnoid space, another arachnoid mater to the surface of the brain ·Arachnoid villi are extensions of the arachnoid mater penetrating the dura mater & the superior sagittal sinus returning CSF to circulation |
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About The Dura Mater [tough mother] |
Superficial, very fibrous meninx; double layered in the skull; -Periosteal layer: continuous with the periosteum of skull; this layer is absent in vertebrae -Meningeal layer: surrounds brain & spinal cord; forms the dura septa (falx cerebri) in the longitudinal fissure separating the cerebral hemispheres (reduces brain movement) |
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About The Pia Mater [gentle mother] |
·Deepest meninx on surface of brain; very thin and delicate ·Separated brain tissue from CSF and provides attachment site for arachnoid fibers and blood vessels |
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The Central Nervous System consist of what? |
The Spinal Cord |
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About The Central Nervous System: The Spinal Cord |
· The spinal cord is a continuation of the medulla oblongata within the spinal cavity ·It begins at the foramen magnum and ends as the conus terminalis, or conus medullaris (medullary cone) at the level of L1 or L2 ·It gives ride to 31 pairs of spinal nerves, each exits the spinal cavity via intervertebral or sacral foramina, or the sacral hiatus ·Beyond the conus terminalis, spinal nerves of lumbar, sacral, and coccygeal travel within the spinal cavity as the cauda equina [Horse tail] before exiting at their respective level ·The spin cavity terminates by an extension of the Pia Mater which anchors the spinal cord to the coccyx, the filum terminate [terminal thread] |
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Cross-Sectional Anatomy of the Spinal Cord |
·The spinal cord consists of a central area of gray matter divided into two dorsal horns, and two ventral horns ·The right and left halves are connected by the gray commisure , in the center is the central canal ·Sensory fibers enter the dorsal horn, sometimes synapse with an interneuron, and exit by way of the ventral root (motor fibers) of the spinal nerve ·White matter consists of bundles of myelinated axons that run up and down the cord, to and from the brain. White matter is arranged into dorsal, lateral, and ventral columns |
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Peripheral Nervous System |
The peripheral nervous system includes all nervous system structures outside of the brain & spinal cord |
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Nerves, the Organs :: What are the three connective tissue tunics organize and compartmentalize nerve fibers to form a nerve? |
1. Endoneurium: wraps each nerve fiber 2.Perineurium: wraps groups of fibers into fascicles 3. Epineurium: encloses all fascicles forming the outer tunic of the nerve; areas enclosed between fascicles, the interfascicular space, contains adipose & areolar connective tissue, and blood & lymph vessels |
Nerves are bundles of nerve fibers (axons) in the PNS |
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What are the three types of nerves that are based on how they trasnmit impulses between the CNS & PNS ( w. Sensory or motor fibers)? |
1. Sensory (afferent) Nerves: CNS <-- PNS (sensory fibers only) 2. Motor (efferent) Nerves: CNS --> PNS (motor fibers only) 3. Mixed Nerves: CNS<==> PNS (both sensory & motor fibers) |
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Spinal Nerves |
·Spinal nerves connect the CNS to sensory receptors, muscles, and glands ·Because they are to the periphery of the spinal cord, they are all in the PNS ·The 31 pairs of spinal nerves are named according to adjacent vertebrae -8 cervical pairs, C1-C8, (C1 emerge between atlas & skull) -12 Thoracic pairs, T1-T12 -5 Lumbar pairs, L1-L5;cauda equina in part; -5 sacral pairs, S1-S5;caudate equina in part; S1-S4 exits via sacral foramina, S5 exits via sacral hiatus -1 coccygeal pair, C0; cauda equina in part; exits via sacral hiatus |
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Spinal Nerves & Branches |
·Spinal nerves have two separate attachment points: 1. Ventral root: contains motor fibers 2. Dorsal root: contains sensory fibers from dorsal root ganglion ·The roots unite at the intervertebral foramen forming the spinal nerve, a "mixed nerve" ·From the spinal nerve, primary branches develop called rami [branches] (sin. Ramus) 1.Dorsal rami: serve skin & muscles dorsally 2. Ventral rami: of T2-T12 form the intercostal nerves which serve skin & muscles laterally & ventrally; all other rami C1-T1, L1-C0, form nervous plexuses which serve the appendages 3. Rami communicantes (communicating branches): serves the autonomic nervous system by forming the sympathetic chain ganglia (paravertebral ganglia) |
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Cranial Nerves |
·Associated with the brain are 12 pairs for cranial nerves ·All exit the cranial cavity by various foramina ·All attach to the brainstem, except the olfactory nerve which attaches to the temporal lobe of the cerebrum ·All innervate the head & neck, except the vagus nerve which enters the ventral body cavity |
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Cranial Nerve-Fibers-Function-Passage (CHART) |
1. Olfactory-Sensory-Smell-Cribriform Foramina 2.Optic-Sensory-Vision-Optic Foramen 3. Oculomotor-Motor-Eye Movement-Superior Orbital Fissure 4. Trochlear-Motor-Eye Movement(superior oblique)- Superior Orbital Fissure 5. Trigeminal 6. Ophthalmic-Sensory-General Sensory:Upper Third of Face-Superior Orbital Fissure 7. Maxillary-Sensory-General Sensory:middle third of Face-Foramen rotundum and infraorbital foramen 8. Mandibular-Mixed- General Sensory: lower third of face and mouth floor, Muscles of mastication-Foramen Ovale 9. Abducens-Motor-Eye Movement (lateral rectus)-Superior Orbital Fissure 10. Facial-Mixed-Muscles of facial expression:all glands of head except the parotid; taste anterior 2/3 of tongue-Stylomastoid foramen 11. Vestibulocochlear-Sensory-Hearing & Equilibrium- Internal Auditory Meatus 12. Glossopharyngeal-Mixed-Swallowing,Salvation (parotid), gag reflex,blood pressure & respiration regulation,general sensory of tongue & outer ear, taste posterior 1/3-Jugular Foramen 13. Vagus-Mixed-Swallowing,taste;speech; pulmonary,cardiovascular,And gastrointestinal regulation; sensations of the hunger, fullness,and intestinal discomfort-Jugular Foramen 14. Accessory-Motor-Muscles of swallowing;trapezius & sternocleidomastoideus-Jugular Foramen 15. Hypoglossal-Motor- Intrinsic & Extrinsic tongue muscles-hypoglossal canal |
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