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Chapter 13 The Peripheral Nervous System

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nanapuge's version from 2017-10-17 20:33

Section

Question Answer
What does the peripheral nervous system (PNS) consist of?1. all neural structures outside the brain- a. sensory receptors b. peripheral nerves and associated ganglia c. motor endings
What is the structure of a nerve?1. cordlike organ of the PNS 2. bundle of myelinated and unmyelinated peripheral axons enclosed by connective tissue
What does the connective tissue covering the structure of a nerve consist of?1. endoneurium 2. perineurium 3. epineurium
Endoneuriumloose connective tissue that encloses axons and their myelin sheaths
Perineuriumcoarse connective tissue that bundles fibers into fascicles
Epineuriumtough fibrous sheath around a nerve
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Most nerves are mixtures of what?1. mixtures of afferent and efferent fibers and somatic and autonomic (visceral) fibers 2. pure sensory (afferent) or motor (efferent) nerves are rare
What are the types of fibers in mixed nerves?1. somatic afferent and somatic efferent 2. visceral afferent and visceral efferent
What do peripheral nerves classify as? classify as cranial or spinal nerves
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What do ganglia contain?contain neuron cell bodies associated with nerves1. dorsal root ganglia (sensory, somatic) 2. autonomic ganglia (motor, visceral)
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How many cranial nerves are there?12 pairs of nerves associated with the brain
What is the broad range of function that the cranial nerves partake in?most are mixed in function; two pairs are purely sensory
How are the cranial nerves identified?identified by a number (I through XII) and a name
Nomadic to remember the cranial nerves?On Occasion, Our Trusty Truck Acts Funny-Very Good Vehicle Anyhow
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Question Answer
What is the name of Cranial Nerve I?The Olfactory Nerve
Where does cranial nerve I arise from?arise from the olfactory receptor cells of nasal cavity
What does cranial nerve I pass through?passes through the cribriform plate of the ethmoid bone
Where do the fibers of cranial nerve I synapse?fibers synapse in the olfactory bulbs
Where does the pathway of cranial nerve I terminate?terminates in the primary olfactory cortex
What is the function of cranial nerve I?purely SENSORY (olfactory) function
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What is the name of Cranial Nerve II?The Optic Nerve
Where does cranial nerve II arise from?arise from the retinas
What does cranial nerve II pass through?1. passes through the optic canals, converge and partially cross over at the optic chiasma 2. optic tracts continue to the thalamus, where they synapse
Where do the optic radiation fibers run?run to the occipital (visual) cortex
What is the function of cranial nerve II?Purely SENSORY (visual) function
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What is the name of Cranial Nerve III?The Oculomotor Nerves
What is the pathway of the fibers for cranial nerve III?fibers extend from the ventral midbrain through the superior orbital fissures to the extrinsic eye muscles
What is the function of cranial nerve III?functions in raising the eyelid, directing the eyeball, constricting the iris (parasympathetic), and controlling lens shape
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What is the name of Cranial Nerve IV?The Trochlear Nerve
What is the pathway of the fibers for cranial nerve IV?fibers from the dorsal midbrain enter the orbits via the superior orbital fissures to innervate the superior oblique muscle
What is the function of cranial nerve IV?primarily a motor nerve that directs the eyeball
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What is the name of Cranial Nerve V?The Trigeminal Nerve
What is the pathway of the fibers for cranial nerve V?largest cranial nerves; fibers extend from pons to face
What are the three divisions of cranial nerve V?1. ophthalmic (V1) passes through the superior orbital fissure 2. Maxillary (V2) passes through the foramen rotundum 3. Mandibular (V3) passes through the foramen ovale
What is the function of cranial nerve V?convey sensory impulses from various areas of the face (V1) and (V2), and supplies motor fibers (V3) for mastication
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What is the name of Cranial Nerve VI?The Abducens Nerve
What is the pathway of the fibers for cranial nerve VI?fibers from the inferior pons enter the orbits via the superior orbital fissures
What is the function of cranial nerve VI?primarily a motor, innervating the lateral recuts muscle
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What is the name of Cranial Nerve VII?The Facial Nerve
What is the pathway of the fibers for cranial nerve VII?fibers from the pons travel through the internal acoustic meatuses, and emerge through the stylomastoid foramina to the lateral aspect of the face
What does cranial nerve VII serve as?chief motor nerves of the face with 5 major branches
What are the major MOTOR functions of cranial nerve VII?motor functions include facial expression, parasympathetic impulses to lacrimal and salivary glands
What are the major SENSORY functions of cranial nerve VII?sensory function-TASTE, from the anterior tow-thirds of the tongue
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What is the name of Cranial Nerve VIII?The Vestibulocochlear Nerve
What is the pathway of the fibers for cranial nerve VIII?afferent fibers from the hearing receptors (cochlear division) and equilibrium receptors (vestibular division) pass from the inner ear through the internal acoustic meatuses, and enter the brain stem at the pons-medulla border
What is the function of cranial nerve VIII?mostly SENSORY function; small motor component for adjustment of sensitivity of receptors
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What is the name of Cranial Nerve IX?The Glossopharyngeal Nerve
What is the pathway of the fibers for cranial nerve IX?fibers from the medulla leave the skull via the jugular foramen and run to the throat
What are the MOTOR functions of cranial nerve IX?innervate part of the tongue and pharynx for swallowing, and provide parasympathetic fibers to the parotid salivary glands
What ar the SENSORY functions of cranial nerve IX?fibers conduct taste and general sensory impulses from the pharynx and posterior tongue, and impulses from carotid chemoreceptors and baroreceptors
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What is the name of Cranial Nerve X?The Vagus Nerve
What makes cranial nerve X unique?the only cranial nerve that extends beyond the head and neck region
What is the pathway of the fibers for cranial nerve X?fibers from the medulla exit the skull via the jugular foramen
What kind of fibers are there in cranial nerve X?most motor fibers are parasympathetic fibers that help regulate the activities of the heart, lungs, and abdominal vicera
What is the function of cranial nerve X?Sensory fibers carry impulses from thoracic and abdominal viscera, baroreceptors, chemoreceptors, and taste buds of posterior tongue and pharynx
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What is the name of Cranial Nerve XI?The Accessory Nerve
What forms cranial nerve XI?formed from ventral rootlets from the C1-C5 region of the spinal cord (not the brain)
What is the pathway of rootlets of cranial nerve XI?rootlets pass into the cranium via each foramen magnum
How do accessory nerves of cranial nerve XI exit the skull?via the jugular foramina to innervate the trapezius and sternocleidomastoid muscles
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What is the name of Cranial Nerve XII?The Hypoglossal Nerve
What is the pathway of the fibers for cranial nerve XII?fibers from the medulla exit the skull via the hypoglossal canal
What is the function of cranial nerve XII?innervate extrinsic and intrinsic muscles of the tongue that contribute to swallowing and speech
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Question Answer
How many pairs of spinal nerves are there?31 pairs of mixed nerves named according to their point of issue from the spinal cord
How are the spinal nerves named?named according to their point of issue from the spinal cord 1. 8 cervical (C1-C8) 2. 12 thoracic (T1-T12) 3. 5 lumbar (L1-L5) 4. 5 sacral (S1-S5) 5. 1 Coccygeal (C0)
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How does each spinal nerve connect to the spinal cord?each spinal nerve connects to the spinal cord via two roots
Define ventral roots1. contain motor (efferent) fibers from the ventral horn motor neurons 2. fibers innervate skeletal muscles
Define dorsal roots1. contain sensory (afferent) fibers from sensory neurons in the dorsal root ganglia 2. conduct impulses from peripheral receptors
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What forms when the dorsal and ventral roots unite?dorsal and ventral roots unite to form spinal nerves, which then emerge from the vertebral column via the intervertebral foramina
Define ramieach spinal nerve branches into mixed rami
What are the two rami?1. dorsal ramus 2. larger ventral ramus
What does each spinal nerve branch into?1. dorsal ramus 2. larger ventral ramus 3. menigeal branch
Where do rami communications occur?rami communications (autonomic pathways) join to the ventral rami in the thoracic region
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Define plexusnerve networks
What makes up the spinal nerve rami?all ventral rami except T2-T12 form interlacing nerve networks (plexuses)- cervical, brachial, lumbar, sacral
What are the four types of plexuses?1. cervical 2. brachial 3. lumbar 4. sacral
What innervates the back?innervated by dorsal rami via several branches
What supplies muscles of the ribs, anterolateral thorax and abdominal wall?ventral rami T2-T12 as intercostal nerves
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What forms the cervical plexus?ventral rami of C1-C4
What does the cervical plexus innervate?skin and muscles of the neck, ear, back of head, and shoulders
Define Phrenic nervemajor motor and sensory nerve of the diaphragm
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What forms the Brachial plexus?formed by ventral rami of C5-C8 and T1 (and often C4 and T2)
What is the function of the brachial plexus?gives rise to the nerves that innervate the upper limb
What are the major branches of the brachial plexus?1. roots- five ventral rami (C5-T1) 2. trunks-upper, middle, lower 3. divisions-anterior and posterior 4. cords-lateral, medial, posterior
What is the nomonic for remebering the branches of the brachial plexus?Robert Taylor Drinks Cold Beer
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What are the brachial plexus nerves?1. axillary 2. musculocutaneous 3. median 4. ulnar 5. radial
Define axillary nerveinnervates the deltoid, teres minor, and skin and joint capsule of the shoulder
Define Musculocutaneous nerveinnervates the biceps brachii and brachialis and skin of lateral forearm
Define Median nerveinnervates the skin, most flexors and pronators in the forearm, and some intrinsic muscles of the hand
Define Ulnar nervesupplies the flexor carpi ulnaris, part of the flexor digitorum profundus, most intrinsic muscles of the hand, and skin of medial aspect of hand
Define Radial nerveinnervates essentially all extensor muscles, supinators, and posterior skin of limb
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Question Answer
Where does the Lumbar plexus arise from?arises from L1-L4
What does the lumbar plexus innervate?thigh, abdominal wall, psoas muscle
What does the femoral nerve innervate?quadriceps, skin of anterior thigh, medial surface of leg
What does the obturator nerve innervate?adductor muscles
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Where does the Sacral plexus arise from?arises from L4-S4
What does the sacral plexus serve?serves the buttock, lower limb, pelvic structures, and perineum
Define Sciatic nervelongest and thickest nerve of the body
What does the sciatic nerve innervate?innervates the hamstring muscles, adductor magnus, and most muscles of the leg and foot
What is the sciatic nerve composed of?composed of two nerves
What are the two nerves that the sciatic nerve is composed of?1. tiabial 2. common fibular
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Question Answer
Define dermatomethe area of skin innervated by the cutaneous branches of a single spinal nerve
what participates in dermatomes?all spinal nerves except C1
What can happen with dermatomes?most dermatomes overlap, so destruction of a single spinal nerve will not cause complete numbness
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Hiltons's lawany nerve serving a muscle that produces movement at a joint also innervates the joint and the skin over the joint
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