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42 Cards in this Set
- Front
- Back
–Mixed nerves |
– both sensory and motor fibers; impulses both to and from CNS |
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Sensory (afferent) nerves |
– impulses only toward CNS |
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Motor (efferent) nerves |
– impulses only away from CNS |
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Somatic afferent: |
from skin, skeletal muscles or joints |
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Visceral afferent: |
from organs within ventral body cavity (stomach, bladder, etc.) |
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Somatic efferent: |
voluntary, skeletal muscle |
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–Visceral efferent: |
involuntary, cardiac muscle, smooth muscle, or glands |
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Crainial Nerve I |
• I. Olfactory – if damaged, loss of smell |
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Crainial Nerve II |
• II. Optic – if severed, blindness in eye served by that nerve |
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Crainial Nerve III |
III. Oculomotor –if damaged: eye cannot move up, down, or inward & at rest, eye will rotate laterally |
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Crainial nerve IV |
IV. Trochlear – controls superior oblique muscle; if damaged results in double vision & reduced ability to rotate eye inferior & lateral |
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Cranial nerve V |
V. Trigeminal – sensory fibers to face & motor fiber to chewing muscles; inflammation results in most excruciating pain known; relentless; in extreme cases, nerve will be severed resulting in loss of sensation to that side of face |
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Cranial nerve VI |
VI. Abducens - supplies lateral rectus; if damaged eyeball cannot be moved laterally, at rest, eye will rotate medially |
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Cranial nerve VII |
VII. Facial – supplies nerves of facial expression; if damaged paralyze facial muscles on affected side (Bell’s palsy, caused by herpes simplex I virus) |
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Cranial nerve VIII |
VIII. Vestibulocochlear – sensory nerve for hearing & equilibrium; – Cochlear damaged then nerve deafness; – Vestibular damaged produces dizziness, loss of balance, nausea, vomiting |
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Cranial nerve IX |
IX. Glossopharyngeal –supplies nerves for tongue (taste) & pharynx; if damaged, impairs swallowing & taste |
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Cranial nerve X |
X. Vagus – mixed only nerve to extend beyond head & neck to supply the thorax & abdomen; • if damaged, loss of voice or hoarseness; • if both vagus nerves severed, fatal because parasympathetic shut down |
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Cranial nerve XI |
XI. Accessory – supplies trapezius and sternocleidomastoid; if damaged causes head to turn toward injury side as result of sternocleidomastoid muscle paralysis; also difficult to shrug shoulders (trapezius |
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Cranial nerve XII |
XII. Hypoglossal – supplies some tonguemoving muscles: if damaged difficult to swallowing & impairs speech; if both nerves damaged, cannot protrude tongue |
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– Neuron cell bodies within special sense organs |
Olfactory and optic nerves
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Distribution of the 31 pairs of cranial nerves |
– 8 cervical (C1–C8) – 12 thoracic (T1–T12) – 5 Lumbar (L1–L5) – 5 Sacral (S1–S5) – 1 Coccygeal (C0) |
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Ventral roots |
– Contain motor (efferent) fibers from ventral horn motor neurons – Fibers innervate skeletal muscles |
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Dorsal roots |
– Contain sensory (afferent) fibers from sensory neurons in dorsal root ganglia and conduct impulses from peripheral receptors |
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Dorsal & ventral roots unite |
= spinal nerves |
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Rami: |
contain both sensory & motor fibers |
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Rami communicantes: |
contains autonomic (visceral) nerve fibers that allow communication of adjoining spinal nerves |
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Plexuses |
• Network of nerves that join together; form from ventral rami only |
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4 major spinal plexuses: |
cervical, brachial, lumbar, and sacral regions, but no thoracic! |
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– This is why damage to one spinal segment cannot completely paralyze a limb muscle |
Each muscle in a limb receives a nerve supply from more than one spinal nerve
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Phrenic nerve |
– Responsible for contraction in breathing • irritation of phrenic causes “diaphragm spasms” or hiccups • paralysis of phrenic causes respiratory arrest |
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Median— |
innervates the skin, most flexors and pronators in forearm, and some intrinsic muscles of the hand, damage makes it hard to use pincer grasp frequent casualty of suicide attempt; compressed in carpel tunnel |
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Ulnar— |
supplies forearm flexors; trauma to ulnar damages “funny bone” results in tingling |
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Radial— |
innervates essentially all extensor muscles, supinators, and posterior skin of limb; trauma results in wrist drop (can’t extend hand at the wrist |
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Axillary— |
innervates the deltoid, teres minor, and skin and joint capsule of the shoulder |
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Lumbar Plexus |
• Innervates thigh, abdominal wall, and psoas muscle |
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Femoral nerve |
—innervates quadriceps and skin of anterior thigh and medial surface of leg; controls muscles of hip flexion & knee extension |
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Obturator nerve |
—passes through obturator foramen to innervate adductor muscles; pain in medial thigh if nerve impaired |
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Sacral Plexus |
• Serves the buttock, lower limb, pelvic structures, and perineum |
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Sciatic nerve |
– Longest and thickest nerve of body – Innervates hamstring muscles, adductor magnus, and most muscles in leg and foot – Composed of two nerves: tibial and common fibular – if severed, cannot flex, foot drops into plantar flexion, leg is nearly useless |
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Pudendal: |
serves perineum region (external genitalia & anus) & anal & bladder sphincters, – Helps stimulate erections – Aids voluntary control of urination |
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Reflexes • Inborn (intrinsic) reflex |
- rapid, involuntary, unlearned, unpremeditated predictable motor response to stimulus – Example – you splash hot water & drop the pot before you even feel pain – Can be modified by learning and conscious effort
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Learned (acquired) reflexes |
result from practice or repetition, – Example – driving skills |