Anatomy & Physiology ch 14
Anatomy & Physiology ch 14 Biol 2301
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Human Anatomy & Physiology, 8e (Marieb/Hoehn) Chapter 13 The Peripheral Nervous System and Reflex Activity Matching Questions Figure 13.1 Using Figure 13.1, match the following: 1) Innervates the superior oblique muscle. Answer: B Diff: 2 Page Ref: 496; Fig. 13.5 2) Longest cranial nerve. Answer: D Diff: 2 Page Ref: 500; Fig. 13.5 3) Damage to this nerve would cause dizziness, nausea, and loss of balance. Answer: C Diff: 2 Page Ref: 499; Fig. 13.5 4) Involved in movement of the digestive tract. Answer: D 1 Copyright © 2010 Pearson Education, Inc. Diff: 2 Page Ref: 500; Fig. 13.5 5) Damage to this nerve would cause difficulty in speech and swallowing, but no effect on visceral organs. Answer: E Diff: 2 Page Ref: 501; Fig. 13.5 6) Damage to this nerve would keep the eye from rotating inferolaterally. Answer: B Diff: 2 Page Ref: 496; Fig. 13.5 Figure 13.2 Using Figure 13.2, identify the following components of the reflex arc: 7) Integration center. Answer: E Diff: 1 Page Ref: 514; Fig. 13.14 8) Sensory neuron. Answer: C Diff: 1 Page Ref: 514; Fig. 13.14 9) Effector. Answer: B Diff: 1 Page Ref: 514; Fig. 13.14 10) Motor neuron. Answer: D Diff: 1 Page Ref: 514; Fig. 13.14 11) Receptor. Answer: A Diff: 1 Page Ref: 514; Fig. 13.14 2 Copyright © 2010 Pearson Education, Inc. Match the following: A) Accessory B) Vagus C) Vestibulocochlear D) Olfactory E) Abducens 12) Formed by the union of a cranial and a spinal root. Diff: 2 Page Ref: 501 13) Receptors located in epithelium of the nasal cavity. Diff: 1 Page Ref: 495 14) Serves the senses of hearing and equilibrium. Diff: 2 Page Ref: 499 15) Helps to regulate blood pressure and digestion. Diff: 3 Page Ref: 500 16) Turns the eyeball laterally. Diff: 2 Page Ref: 498 Answers: 12) A 13) D 14) C 15) B 16) E Match the following reflexes to their function: A) Crossedextensor B) Plantar C) Golgi tendon D) Stretch E) Flexor 17) Tests both upper and lower motor pathways. The sole of the foot is stimulated with a dull instrument. Diff: 2 Page Ref: 519 18) Consists of an ipsilateral withdrawal reflex and a contralateral extensor reflex; important in maintaining balance. Diff: 2 Page Ref: 519 19) Produces a rapid withdrawal of the body part from a painful stimulus; ipsilateral. Diff: 2 Page Ref: 518519 20) Prevents muscle overstretching and maintains muscle tone. 3 Copyright © 2010 Pearson Education, Inc. Diff: 2 Page Ref: 515; Fig. 13.17 21) Produces muscle relaxation and lengthening in response to tension; the contracting muscle relaxes as its antagonist is activated. Diff: 2 Page Ref: 518 Answers: 17) B 18) A 19) E 20) D 21) C Match the following: A) Sacral plexus B) Brachial plexus C) Cervical plexus D) Lumbar plexus 22) The obturator and femoral nerves branch from this plexus. Diff: 1 Page Ref: 508; Fig. 13.10 23) Striking the "funny bone" (ulnar nerve) may cause injury to a nerve of this plexus. Diff: 1 Page Ref: 505; Fig. 13.9 24) Trauma to a nerve of this plexus may cause wrist drop. Diff: 2 Page Ref: 505; Fig.13.9 25) A fall or improper administration of an injection to the buttocks may injure a nerve of this plexus. Diff: 2 Page Ref: 509; Fig. 13.11 26) The phrenic nerve branches from this plexus. Diff: 2 Page Ref: 504; Fig. 13.8 Answers: 22) D 23) B 24) B 25) A 26) C Match the following: A) Precommand level B) Segmental level C) Projection level 27) Controls the outputs of the cortex and regulates motor activity. Diff: 2 Page Ref: 513; Fig. 13.13 28) Central pattern generators. Diff: 2 Page Ref: 512; Fig. 13.13 4 Copyright © 2010 Pearson Education, Inc. 29) Intermediate relay for incoming and outgoing neurons. Diff: 2 Page Ref: 512; Fig. 13.13 5 Copyright © 2010 Pearson Education, Inc. 30) The cerebellum and basal nuclei. Diff: 2 Page Ref: 513; Fig. 13.13 31) Includes cortical and brain stem motor areas. Diff: 2 Page Ref: 512: Fig. 13.13 32) The neural machinery of the spinal cord, including spinal cord circuits. Diff: 2 Page Ref: 512: Fig. 13.13 Answers: 27) A 28) B 29) C 30) A 31) C 32) B Figure 13.3 Using Figure 13.3, match the following: 33) Contain autonomic nerve fibers. Answer: C Diff: 1 Page Ref: 502; Fig. 13.7 34) Supplies the posterior body trunk. Answer: A Diff: 1 Page Ref: 502; Fig. 13.7 35) Supplies all of the body except the posterior. Answer: B Diff: 1 Page Ref: 502; Fig. 13.7 36) All but T2T 12ranch and form nerve plexuses. Answer: A Diff: 1 Page Ref: 502; Fig. 13.7 6 Copyright © 2010 Pearson Education, Inc. 7 Copyright © 2010 Pearson Education, Inc. 37) Supplies each muscle with fibers from more than one nerve. Answer: B Diff: 1 Page Ref: 502; Fig. 13.7 True/False Questions 1) The meningeal branch of a spinal nerve actually reenters the vertebral canal to innervate the meninges and blood vessels. Answer: TRUE Diff: 1 Page Ref: 502 2) In the somatosensory system there are no thirdorder neurons in the cerebellum. Answer: TRUE Diff: 2 Page Ref: 489; Fig.13.2 3) There are 41 pairs of spinal nerves. Answer: FALSE Diff: 1 Page Ref: 502; Fig.13.6 4) The glossopharyngeal nerve is the only cranial nerve that contains sensory fibers. Answer: FALSE Diff: 1 Page Ref: 494; Fig.13.5 5) The musculocutaneous nerve is a major nerve of the brachial plexus. Answer: TRUE Diff: 1 Page Ref: 505 6) The second cranial nerve forms a chiasma at the base of the brain for partial crossover of neural fibers. Answer: TRUE Diff: 1 Page Ref: 495 7) The only cranial nerves to extend beyond the head and neck region are the vagus nerves. Answer: TRUE Diff: 1 Page Ref: 500 8) The dorsal ramus consists only of motor fibers bringing information to the spinal cord. Answer: FALSE Diff: 1 Page Ref: 502 9) Dermatomes are skin segments that relate to sensory innervation regions of the spinal nerves. Answer: TRUE Diff: 1 Page Ref: 510 10) Dorsal and ventral rami are similar in that they both contain sensory and motor fibers. 8 Copyright © 2010 Pearson Education, Inc. Answer: TRUE Diff: 1 Page Ref: 502 11) Irritation of the phrenic nerve may cause diaphragm spasms called hiccups. Answer: TRUE Diff: 1 Page Ref: 505 12) The obturator nerve branches from the sacral plexus. Answer: FALSE Diff: 2 Page Ref: 507 13) Reciprocal inhibition means that while one sensory nerve is stimulated, another sensory neuron for synergistic muscles in the same area is inhibited and cannot respond. Answer: FALSE Diff: 2 Page Ref: 516 14) External strabismus and ptosis could be caused by damage to the oculomotor nerve. Answer: TRUE Diff: 2 Page Ref: 496 15) The cerebellum and basal nuclei are involved in regulating motor activity, starting and stopping movements, and coordinating postural movements. Answer: TRUE Diff: 2 Page Ref: 513 MultipleChoice Questions 1) The patellar "knee jerk" reflex is an example of a(n) ________. A) extensor thrust reflex B) stress reflex C) crossedextensor reflex D) stretch reflex Answer: D Diff: 1 Page Ref: 515516 2) The ________ nerve is not a branch of the trigeminal nerve. A) ophthalmic B) maxillary C) cervical D) mandibular Answer: C Diff: 1 Page Ref: 497 3) Which of the following nerves does not arise from the brachial plexus? A) median 9 Copyright © 2010 Pearson Education, Inc. B) phrenic C) radial D) ulnar Answer: B Diff: 1 Page Ref: 504505 4) Which of the following is not an example of an exteroceptor? A) touch B) pressure C) pain D) temperature E) baroreceptor Answer: E Diff: 2 Page Ref: 486 5) Which of the following is not a main level of neural integration in the somatosensory system? A) receptor B) circuit C) segmental D) perceptual Answer: C Diff: 1 Page Ref: 489 6) The posterior side of the thigh, leg, and foot is served by the ________ nerve. A) obturator B) common fibular C) tibial D) femoral Answer: C Diff: 1 Page Ref: 510 7) Starting at the spinal cord, the subdivisions of the brachial plexus are (in order): A) roots, trunks, divisions, and cords B) roots, divisions, cords, and trunks C) divisions, roots, trunks, and cords D) trunks, divisions, cords, and roots Answer: A Diff: 1 Page Ref: 505; Fig. 13.9 8) The cranial nerve with a dual origin (brain and spinal cord) is the ________. A) hypoglossal B) accessory C) vagus D) glossopharyngeal Answer: B 10 Copyright © 2010 Pearson Education, Inc. Diff: 1 Page Ref: 501 9) Which of the following is an incorrect statement regarding the occurrence of a sensation? A) The stimulus energy must match the specificity of the receptor. B) The stimulus energy must occur within the receptor’s receptive field. C) The stimulus energy must be converted into the energy of a graded potential called a transduction potential. D) A generator potential in the associated sensory neuron must reach threshold. Answer: C Diff: 2 Page Ref: 489 10) A major nerve of the lumbar plexus is the ________. A) femoral B) iliohypogastric C) sciatic D) ilioinguinal Answer: A Diff: 2 Page Ref: 507 11) Spinal nerves exiting the cord from the level of L4 to 4 form the ________. A) lumbar plexus B) femoral plexus C) sacral plexus D) thoracic plexus Answer: C Diff: 1 Page Ref: 509 12) The abducens nerve ________. A) supplies innervation to the lateral rectus muscle of the eye B) relays sensory information from taste buds on the tongue C) exits from the medulla D) if paralyzed, exhibits Bell's palsy Answer: A Diff: 1 Page Ref: 498 13) Inborn or intristic reflexes are ________. A) rapid, predictable, learned responses B) involuntary, yet may be modified by learned behavior C) autonomic only D) always mediated by the brain Answer: B Diff: 1 Page Ref: 514 14) Which of the following is not an aspect of sensory perception? A) magnitude estimation 11 Copyright © 2010 Pearson Education, Inc. B) spatial discrimination C) feature attraction D) quality estimation E) pattern recognition Answer: D Diff: 2 Page Ref: 490 12 Copyright © 2010 Pearson Education, Inc. 15) Striking the "funny bone" is actually stimulation of (or injury to) the ________. A) radial nerve B) sciatic nerve C) ulnar nerve D) median nerve Answer: C Diff: 1 Page Ref: 505 16) A reflex that causes muscle relaxation and lengthening in response to muscle tension is called a ________. A) Golgi tendon reflex B) flexor reflex C) crossedextensor reflex D) plantar reflex Answer: A Diff: 1 Page Ref: 518 17) Pressure, pain, and temperature receptors in the skin are ________. A) interoceptors B) exteroceptors C) proprioceptors D) mechanoreceptors Answer: B Diff: 1 Page Ref: 486 18) Potentially damaging stimuli that result in pain are selectively detected by ________. A) interoceptors B) photoreceptors C) nociceptors D) proprioceptors Answer: C Diff: 1 Page Ref: 485 19) Which receptors adapt most slowly? A) smell receptors B) pressure receptors C) nociceptors D) touch receptors Answer: C Diff: 3 Page Ref: 487; Tbl. 13.1 13 Copyright © 2010 Pearson Education, Inc. 20) The trochlear nerve conveys proprioceptor impulses from the ________ to the brain. A) medial rectus muscle B) lateral rectus muscle C) superior rectus muscle D) inferior rectus muscle Answer: C Diff: 1 Page Ref: 496 21) Nerves that carry impulses toward the CNS only are ________. A) afferent nerves B) efferent nerves C) motor nerves D) mixed nerves Answer: A Diff: 2 Page Ref: 491 22) After axonal injury, regeneration in peripheral nerves is guided by ________. A) Wallerian cells B) Schwann cells C) dendrites D) Golgi organs Answer: B Diff: 1 Page Ref: 491492 23) Regeneration within the CNS ________. A) is more successful than with the PNS B) typically allows axonal sprouting of 20 mm C) is prevented due to growthinhibiting proteins of oligodendrocytes D) is promoted by growth inhibitors and glial scars Answer: C Diff: 1 Page Ref: 491492 24) In a crossedextensor reflex, if the right arm was grabbed it would flex and the left arm would ________. A) also flex B) extend C) abduct D) adduct Answer: B Diff: 1 Page Ref: 519 25) Select the correct definition. A) Magnitude estimation is the simplest level of sensation. B) Perceptual detection is the ability to detect how much stimulus is applied to the body. C) Pattern recognition allows us to see a familiar face. 14 Copyright © 2010 Pearson Education, Inc. D) Spatial discrimination allows us to recognize textures. Answer: C Diff: 2 Page Ref: 490 26) All processing at the circuit level going up to the perceptual level must synapse in the ________. A) pons B) thalamus C) reticular formation D) medulla Answer: B Diff: 1 Page Ref: 490 27) The sciatic nerve is a combination of which two nerves? A) pudendal and posterior femoral cutaneous B) posterior femoral cutaneous and tibial C) pudendal and common fibular D) common fibular and tibial Answer: D Diff: 1 Page Ref: 509510 28) Irritation of a major nerve of this plexus may cause hiccups. A) cervical plexus B) lumbar plexus C) sacral plexus D) thoracic plexus Answer: A Diff: 1 Page Ref: 504505 29) Bell's palsy is ________. A) characterized by partial paralysis of diaphragm muscles B) characterized by loss of vision C) often caused by inflammation of the trigeminal nerve D) characterized by paralysis of facial muscles Answer: D Diff: 1 Page Ref: 498 30) Which of the following is the correct simple spinal reflex arc? A) effector, afferent neuron, integration center, efferent neuron, receptor B) receptor, afferent neuron, integration center, efferent neuron, effector C) effector, efferent neuron, integration center, afferent neuron, receptor D) receptor, efferent neuron, integration center, afferent neuron, effector Answer: B Diff: 2 Page Ref: 514 15 Copyright © 2010 Pearson Education, Inc. 31) Mixed cranial nerves containing both motor and sensory fibers include all except which of the following? A) oculomotor B) olfactory C) trigeminal D) facial Answer: B Diff: 1 Page Ref: 493 32) Transduction refers to conversion of ________. A) presynaptic nerve impulses to postsynaptic nerve impulses B) stimulus information to nerve impulses C) receptor energy to stimulus energy D) afferent impulses to efferent impulses Answer: B Diff: 2 Page Ref: 489 33) The flexor muscles in the anterior arm (biceps brachii and brachialis) are innervated by what nerve? A) radial B) median C) ulnar D) musculocutaneous Answer: D Diff: 2 Page Ref: 505 34) The cranial nerves that have neural connections with the tongue include all except the ________. A) trigeminal B) facial C) glossopharyngeal D) trochlear Answer: D Diff: 2 Page Ref: 496 35) Problems in balance may follow trauma to which nerve? A) abducens B) vestibulocochlear C) trigeminal D) accessory Answer: B Diff: 2 Page Ref: 499 16 Copyright © 2010 Pearson Education, Inc. 36) A fracture of the ethmoid bone could result in damage to which cranial nerve? A) glossopharyngeal B) vagus C) olfactory D) accessory Answer: C Diff: 2 Page Ref: 495 37) Select the statement that is most correct. A) Ganglia are collections of neuron cell bodies in the spinal cord that are associated with efferent fibers. B) Ganglia associated with afferent nerve fibers contain cell bodies of sensory neurons. C) The dorsal root ganglion is a motoronly structure. D) The cell bodies of afferent ganglia are located in the spinal cord. Answer: B Diff: 2 Page Ref: 491 38) A fall or an improperly delivered gluteal injection could result in ________. A) neurofibromatosis B) postpoliomyelitis muscular atrophy C) paresthesia D) sciatica Answer: D Diff: 2 Page Ref: 510 39) Feeling a gentle caress on your arm would likely involve all of the following except ________. A) Meissner's corpuscles B) tactile discs C) Pacinian corpuscles D) hair follicle receptors Answer: C Diff: 2 Page Ref: 486; Tbl. 13.1 40) A patient who received a blow to the side of the skull exhibits the following signs and symptoms on that side of the face: he is unable to close his eye, and the corner of his mouth droops. Which cranial nerve has been damaged? A) facial B) glossopharyngeal C) hypoglossal D) accessory Answer: A Diff: 3 Page Ref: 498 17 Copyright © 2010 Pearson Education, Inc. 41) If the ventral root of a spinal nerve were cut, what would be the result in the tissue or region that nerve supplies? A) complete loss of sensation B) a complete loss of voluntary movement C) loss of neither sensation nor movement but only of autonomic control D) a complete loss of sensation and movement Answer: B Diff: 3 Page Ref: 502 FillintheBlank/Short Answer Questions 1) A pebble kicked up into a shoe causes the ________ of localized deep pressure, but the ________ of it is an awareness of discomfort. Answer: sensation; perception Diff: 2 Page Ref: 488 2) Which receptors are modified freenerve endings found in the deeper levels of the epidermis? Answer: Tactile discs Diff: 1 Page Ref: 486 3) The perineurium defines the boundary of a ________. Answer: fascicle Diff: 1 Page Ref: 491 4) The ________ nerve is the largest of the cranial nerves. Answer: trigeminal Diff: 1 Page Ref: 497 5) Ventral spinal cord roots contain ________ fibers, while the dorsal roots contain ________ fibers. Answer: motor (efferent); sensory (afferent) Diff: 1 Page Ref: 502 6) The facial nerve is cranial nerve number ________. Answer: VII Diff: 1 Page Ref: 498 7) ________ is a protective reflex that also overrides the spinal pathways and prevents any other reflexes from using them at the same time. Answer: Flexor reflex Diff: 2 Page Ref: 518519 8) ________ is the tingling sensation or numbness when blood has been cut off from an area, as when the foot "goes to sleep." Answer: Ischemia 18 Copyright © 2010 Pearson Education, Inc. Diff: 1 Page Ref: 507 9) Pain, temperature, and coarse touch are involved in the ________ ascending pathways of the somatosensory system. Answer: nonspecific Diff: 2 Page Ref: 490 10) Complex motor behavior such as walking depends on ________ patterns. Answer: fixedaction Diff: 1 Page Ref: 512513 11) Information regarding skeletal muscle tension is provided by ________ and muscle length by ________. Answer: Golgi tendon organs; muscle spindles Diff: 2 Page Ref: 488 12) Mr. Smith staggered home after a long night at the local pub. While attempting to navigate the stairs, he passed out cold and lay all night with his right armpit straddling the staircase banister. When he awoke the next morning, he had a severe headache, but what bothered him more was that he had no sensation in his right arm and hand. Explain what caused this symptom in his arm. Answer: Continuous pressure interrupts blood flow along with oxygen and nutrients to the neuron processes. As a result, impulse transmission is inhibited temporarily. Diff: 3 Page Ref: 507 13) Define Golgi tendon organs and muscle spindles relative to the stretch reflex. Answer: Golgi tendon organs work with muscle spindles to act as proprioceptors in skeletal muscles and their associated tendons. When muscles are stretched due to contraction of antagonist muscles, the sensory neurons send impulses to the spinal cord, where they synapse with motor neurons of the stretched muscle. Impulses are then sent to the stretched muscle, which then resists further stretching. This prevents muscle tissue damage. Diff: 3 Page Ref: 515518 14) Distinguish between monosynaptic and polysynaptic reflexes and between ipsilateral and contralateral reflex responses. Answer: Monosynaptic refers to a single synapse in the reflex arc (one sensory and one motor neuron). Polysynaptic refers to more than one synapse in the arc involving sensory neurons, interneurons, and motor neurons. Ipsilateral refers to a reflex arc limited to one side of the spinal cord, while contralateral reflexes cross to the opposite side. Diff: 3 Page Ref: 514, 516 15) What is the normal response of the plantar reflex? What is Babinski's sign and what does it indicate? Answer: The plantar reflex tests the integrity of the spinal cord from L to S and also 4 2 determines if corticospinal tracts are functioning and properly myelinated. The normal plantar 19 Copyright © 2010 Pearson Education, Inc. response is downward flexion of the toes. If there is damage, the great toe dorsiflexes and smaller toes fan laterally (Babinski's sign). Infants, who normally lack complete myelination, exhibit this sign. Diff: 3 Page Ref: 519 16) List and describe the functions of the three cranial nerves that serve the muscles of the eye. Answer: The three cranial nerves are: oculomotor, trochlear, and abducens. The oculomotor is mostly motor, with branches to the inferior oblique and superior, inferior, and medial rectus muscles, as well as to the muscles of the iris and lens. The trochlear supplies mostly motor fibers to the superior oblique muscles of the eye. The abducens supplies mostly motor fibers to the lateral rectus muscles of the eye. Like most motor nerves, they also carry some sensory information for proprioception. Diff: 3 Page Ref: 496, 498 17) Name an exteroceptor that is not a cutaneous receptor and explain why. Answer: Exteroceptors that are not cutaneous receptors include the chemoreceptors of the tongue and nasal mucosa, the photoreceptors of the eyes, and the mechanoreceptors of the inner ear. These all monitor changes in the external environment, so they are classified as exteroceptors. Diff: 3 Page Ref: 486 18) Speculate about the benefit of having the nerve supply of the diaphragm, which is located in the thoraciclumbar area of the spinal cord, arise from cervical nerves. Answer: The fact that the phrenic nerve originates so high in the spinal cord reduces the likelihood of spinal damage above the phrenic origin, thereby reducing the possibility that a spinal injury would stop the diaphragm from working. Diff: 3 Page Ref: 504505 19) How is a receptor potential similar to an excitatory postsynaptic potential (EPSP) generated at a synapse? Answer: A receptor potential acts essentially the same as an EPSP in that stimulus causes changes in permeability of the receptor membrane, which results in a graded potential. It will increase or decrease depending on the intensity of the stimulus. Diff: 3 Page Ref: 489 20) How does accommodation of muscle spindles figure in the importance of stretch routines as a warmup for exercise? Answer: Initially, as muscle spindles are stretched, the reflex sends impulses back to contract the muscle. With prolonged stretching, accommodation decreases the vigor of the stretch reflex somewhat, and the muscle can relax and stretch more, reducing the risk of tearing muscle tissue during exercise. Diff: 3 Page Ref: 518 20 Copyright © 2010 Pearson Education, Inc. 21) Name three unencapsulated sensory receptors and tell what they are used for. Answer: 1. Free nerve endings are found throughout the body. They are used by most body tissues to determine stretching, joint positioning, etc. In the epidermis they become pain receptors, heat and cold receptors, and possibly very light pressure receptors. 2. Modified free nerve endings called tactile disks are used as light touch receptors. 3. Hair follicle receptors are mechanical receptors that become very fine touch receptors. Diff: 2 Page Ref: 487; Tbl. 13.1 22) When we hear a strange sound in a room, which aspect of sensory perception is activated? Answer: The perceptual detection aspect is the only aspect acted upon. In some cases this alone allows our imagination to go "wild" with possibilities. Diff: 2 Page Ref: 490 23) What is Wallerian degeneration? Answer: The complete degeneration of the distal end of an axon after it has been severed. Diff: 2 Page Ref: 491 Clinical Questions 1) Ralph sustained a leg injury in a bowling accident and had to use crutches. Unfortunately, he never took the time to learn how to use them properly. After two weeks of use, he noticed his fingers were becoming numb. Then he noticed his arms were getting weaker and tingling. What could be his problem? Answer: Compression of the radial nerve (in the region of the armpit) may cause temporary cessation of nervous transmission, often called "Saturday night paralysis." Continued pressure could cause permanent damage. Diff: 2 Page Ref: 505507 2) A patient suffers nerve damage to the sciatic nerve, requiring surgery to suture the nerve back together. After surgery, the patient reports that sensation from the lateral and medial sides of the knee seem to be reversed. How could this happen? Answer: In suturing the nerve back together, there is no guide to ensure that each nerve fiber continues across the transection into the same neurilemma in which it started. Nerve fibers can grow into pathways different from their original ones and establish new synapses. The brain cannot keep track of which nerve fibers have grown into different pathways, and projects sensations back to the point of origin. Diff: 3 Page Ref: 491492 3) David, an aspiring baseball player, was struck on the left side of his face with a fastball pitch. He was not wearing a safety helmet. His zygomatic arch was crushed, as well as parts of the temporal bone. Following the accident and reconstructive surgery, he noted that his left lower eyelid was still drooping and the corner of his mouth sagged. What nerve damage did he sustain? Answer: He suffered facial nerve damage on his left side. Due to the bone damage, branches to the eye and jaw were probably damaged. It is possible that the damage could be reversible if the 21 Copyright © 2010 Pearson Education, Inc. nerves were not cut or crushed completely. Diff: 3 Page Ref: 498 4) A nurse is asked about the cause of the excruciating pain of tic douloureux. How should s/he answer? Answer: The excruciating pain is caused by inflammation of the trigeminal nerve. Pressure on the trigeminal nerve root can turn normal stimuli like tooth brushing into painful stimuli. Diff: 2 Page Ref: 497 5) The patient is receiving transcutaneous electrical nerve stimulation (TENS) for back pain. Describe how this may work based on the gate control theory. Answer: According to this theory, smalldiameter nerve fibers carry pain stimuli through a gate, but larger diameter nerve fibers going through the same gate can inhibit the transmission of those pain impulses by closing the gate. The electrical stimulation of the skin's large touch fibers causes the gates to close, thereby inhibiting pain. Diff: 3 Page Ref: 490491 22 Copyright © 2010 Pearson Education, Inc.
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