Lab 16: PNS: Nerves and Autonomic NS Hamilton Answers to Pre- Lab Assignments Pre-Lab Activity 1: 1. a. olfactory nerve b. optic nerve c. oculomotor nerve d. abducens nerve e. trochlear nerve f. trigeminal nerve g. facial nerve h. vestibulocochlear nerve i. glossopharyngeal nerve j. vagus nerve k. accessory nerve l. hypoglossal nerve 2. a. optic nerve b. hypoglossal nerve c. olfactory nerve fibers d. vestibulocochlear nerve Pre-Lab Activity 2: a. 8 b. 1 c. 2 d. 2 e. 6 f. 2 g. 3 h. 9 i. 7 j. 4 k. 10 l. 5 Pre-Lab Activity 3: a. 3 b. 2 c. 1 d. 4 e. 2 f. 3 g. 2 h. 4 i. 2 j. 2 k. 4 l. 3
Pre-Lab Activity 4: 1. sensory, motor, motor, autonomic, somatic 2. the effector is cardiac muscle, smooth muscle, or a gland, rather than skeletal muscle. 3. pupillary reflex ANSWERS TO ACTIVITY QUESTIONS Activity 1 Cranial Nerve (Numeral) Sensory, Motor, or Mixed? Cranial Nerve (Name) Connections to Things I Have Already Learned I Olfactory nerve Sensory Passes through olfactory foramina of ethmoid bone; transmits information concerning smell to the gustatory cortex of the insula II Optic nerve Sensory Passes through optic canal of the sphenoid bone; transmits information concerning vision to the occipital lobe of the cerebrum III Oculomotor nerve Motor Passes through superior orbital fissure of sphenoid bone; one of three eye-movers IV Trochlear nerve Motor Passes through superior orbital fissure of sphenoid bone; one of three eye-movers V Trigeminal nerve Mixed Largest cranial nerve; consists of three branches: ophthalmic, maxillary, and mandibular VI Abducens nerve Motor Passes through superior orbital fissure of sphenoid bone; one of three eye-movers VII Facial nerve Mixed Contains five motor branches: the temporal, zygomatic, buccal, mandibular, and cervical branches VIII IX Vestibulocochlear nerve Passes through internal acoustic meatus and transmits information concerning hearing and equilibrium to cerebral lobes (temporal and insula) Glossopharyngeal nerve Sensory Mixed Glosso means tongue and pharyngeal refers to pharynx ; sensory fibers function in taste; motor fibers function in movements of the pharynx during swallowing X Vagus nerve Mixed The wanderer; innervates heart, lungs, and abdominal organs XI Accessory nerve Motor Innervates sternocleidomastoid m. and trapezius m XII Activity 2 Hypoglossal nerve 1. Observations: student data Cranial nerve(s) evaluated: Motor CN XII Passes through hypoglossal canal of occipital bone and innervates muscles of the tongue; hypo means below and glossal refers to the tongue Abnormal response: Subject is unable to protrude tongue straight out and retract it straight back.
2. Observations: Right eye: student data Left eye: student data Cranial nerve(s) evaluated: CN II Abnormal response: inability to see 20/20 or better 3. Observations: student data Cranial nerve(s) evaluated: CN XI Abnormal response: inability to lift both shoulders against resistance 4. Observations: Unknown substance A student data Unknown substance B : student data Unknown substance C : student data Cranial nerve(s) evaluated: CN I Abnormal response: inability to smell and identify each substance 5. Observations: student data Cranial nerve(s) evaluated: CN III, CN IV, CN VI Abnormal response: inability to follow the clinician s fingers 6. Observations: student data Cranial nerve(s) evaluated: CN V Abnormal response: inability to contract masseter muscles 7. Observations: student data Cranial nerve(s) evaluated: CN VII Abnormal response: inability to perform one or more of these actions 8. Observations: student data Cranial nerve(s) evaluated: CN VIII Abnormal response: inability to hear Activity 3 Nerve Plexus from Which It Arises Function Phrenic Cervical Innervates diaphragm Axillary Brachial Innervates shoulder Musculocutaneous Brachial Innervates forearm flexors and skin of lateral forearm Median Brachial Innervates forearm flexor muscles, several hand muscles, and the skin over the anterior and lateral hand Radial Brachial Innervates the triceps brachii muscle, the extensor muscles of the forearm and hand, and the skin in these regions
Ulnar Brachial Innervates the flexor muscles in the anterior forearm, most intrinsic muscles of the hand, and the skin over the medial hand Femoral Lumbar Innervates muscles of the anterior thigh Saphenous Lumbar Innervates the skin of the anteromedial surface of the thigh and leg Obturator Lumbar Innervates adductor muscles of medial thigh Sciatic Sacral Innervates posterior thigh Tibial Sacral Innervates leg Common fibular Sacral Innervates lateral leg Activity 4 A. Comparing Sympathetic and Parasympathetic Effects Student responses B. Testing the Pupillary Light Reflex 1. What happens to the pupil? It decreases in size. 7. Right Pupil (diameter in mm) Left Pupil (diameter in mm) Initial measurement Student data Student data Light in left eye Student data Student data Light in right eye Student data Student data 8. a. Name each component of the reflex arc in the pupillary reflex. Receptor: photoreceptor Sensory neuron: optic nerve Integration center: brain Motor neuron: oculomotor nerve Effector: smooth muscle of iris b. State two differences between a somatic reflex and an autonomic reflex: A somatic reflex involves a skeletal muscle, whereas an autonomic reflex involves cardiac muscle, smooth muscle, or a gland. Autonomic motor pathways consist of two neurons, whereas somatic motor pathways consist of a single neuron. c. What conclusions can you draw from your data for this activity? Answers will vary. C. Observing the Effects of Exercise on the Sympathetic Nervous System 2. Resting heart rate: student data bpm 3. Resting BP: student data mm Hg 4. Heart rate immediately after exercising: student data bpm BP immediately after exercising: student data mm Hg 5. Heart rate following:
3-minute rest: student data bpm 6-minute rest: student data bpm BP following: 3-minute rest: student data mm Hg 6-minute rest: student data mm Hg 6. a. Which branch of the autonomic nervous system was most active immediately following exercise? How do you know? Sympathetic branch the heart rate and blood pressure were elevated. b. Which branch of the autonomic nervous system was most active following the 6- minute rest period? How do you know? Parasympathetic branch the heart rate and blood pressure decreased. c. What effect does the sympathetic nervous system have on the digestive system? It slows down the activities of the digestive system. d. Sketch the motor pathway that functions in the sympathetic nervous system, and label the preganglionic fiber, ganglion, postganglionic fiber, and effector sketch e. Which receptor types are found on sympathetic target organs? adrenergic receptors (alpha and beta)
ANSWERS TO POST- LAB ASSIGNMENTS PART I. Check Your Understanding Activity 1: Learning the Cranial Nerves 1. Identify the cranial nerves on the accompanying photograph of a human brain. a. olfactory nerve b. trochlear nerve c. abducens nerve d. facial nerve e. hypoglossal nerve f. optic nerve g. oculomotor nerve h. trigeminal nerve i. vestibulocochlear nerve j. vagus k. accessory nerve
Activity 2: Evaluating the Function of the Cranial Nerves 1. Which of the following cranial nerves is classified as a sensory nerve? a. hypoglossal nerve b. vagus nerve c. oculomotor nerve d. olfactory nerve e. More than one of these answers is correct. 2. Which of the following cranial nerves is classified as a mixed nerve? a. optic nerve b. trigeminal nerve c. vestibulocochlear nerve d. accessory nerve e. trochlear nerve 3. In an automobile accident, a woman suffers a crushing hip injury. Which nerve might be damaged if she is unable to flex her leg? a. saphenous nerve b. sciatic nerve c. femoral nerve d. obturator nerve e. median nerve 4. Which cranial nerve is the only cranial nerve to extend beyond the head and neck to the thorax and abdomen? a. trigeminal nerve b. glossopharyngeal nerve c. vagus nerve d. accessory nerve e. abducens nerve 5. Predict the cranial nerve(s) that might be damaged if someone could not: accessory nerve a. shrug the shoulders optic nerve b. see facial nerve c. move the zygomaticus muscle vestibulocochlear nerve d. maintain equilibrium facial nerve e. raise the eyebrows oculomotor, trochlear, abducens nerves f. track objects with the eyes Activity 3: Identifying the Spinal Nerves and Nerve Plexuses 1. Identify the spinal nerves and nerve plexuses on the accompanying illustration. a. cervical plexus b. brachial plexus c. sacral plexus d. lumbar plexus e. cervical nerves f. thoracic nerves g. lumbar nerves h. sacral nerves i. coccygeal nerves
2. Which of the following statements is false? a. There are eight pairs of cervical nerves. b. The lumbar plexus gives rise to the obturator nerve. c. The brachial plexus is deep to the sternocleidomastoid muscle. d. The sacral plexus serves the posterior surface of the thigh. e. The cervical plexus gives rise to the phrenic nerve. 3. In the popliteal region, the sciatic nerve splits to form the tibial nerve and the common fibular nerve. 4. Name the five major nerves that arise from the brachial plexus. axillary n., musculocutaneous n., median n., radial n., ulnar n.
Activity 4: Exploring the Autonomic Nervous System 1. Using the following list of terms, fill in the blanks to complete an outline of the organization of the nervous system: sympathetic branch somatic nervous system PNS motor (efferent) division parasympathetic branch CNS ANS sensory (afferent) division 2. Which of the following reflexes is mediated by the spinal cord? a. patellar reflex b. micturition (urination) reflex c. ejaculation reflex d. erection reflex e. All of these reflexes are mediated by the spinal cord. 3. In the light pupillary reflex, a. which type of receptor is stimulated? photoreceptor b. which nerve transmits sensory information to the brain? optic nerve c. which brain region serves as the integration center? midbrain d. which nerve transmits motor information to the effector? oculomotor nerve e. preganglionic and postganglionic fibers synapse in which ganglion? ciliary f. what is the motor response? contraction of smooth muscle of iris, resulting in constriction of the pupil
4. Are sympathetic effects on the heart similar to or different from sympathetic effects on the activity of the digestive tract? different Explain the physiological significance of this relationship. When exercising, for example, you need to stimulate the heart while at the same time to inhibit activities of the digestive tract. PART II. Putting It All Together A. Review Questions Answer the following questions using your lecture notes, your textbook, and your lab notes. 1. A dentist desensitizes the teeth by injecting a local anesthetic into the alveolar branches of which two divisions of the trigeminal nerve? maxillary and mandibular 2. For each of the following skeletal muscles, (1) name the cranial nerve that innervates it and (2) state one of its major actions. a. Sternocleidomastoid (1) accessory nerve (CN XI) (2) flexes the neck b. Zygomaticus major (1) facial nerve (CN VII) (2) raises lateral corners of mouth c. Lateral rectus (1) abducens nerve (CN VI) (2) moves the eye laterally d. Masseter (1) trigeminal nerve (CN V) (2) elevates the mandible e. Hyoglossus (1) hypoglossal nerve (CN XII) (2) depresses the torgue 3. Which cerebral lobe receives impulses from the vestibular branch of CN VIII? insula 4. Which cerebral lobe receives impulses from CN I? temporal 5. From which two brain regions do the cranial nerves classified as eye-movers emerge? midbrain and pons B. Concept Mapping 1. Fill in the blanks to complete this concept map outlining the anatomy of a spinal nerve. anterior rami anterior roots plexuses posterior roots spinal nerves
2. Construct a unit concept map to show the relationships among the following set of terms. Include all of the terms in your diagram. Your instructor may choose to assign additional terms. accessory nerve anterior rami anterior roots axillary nerve brainstem foramina hypoglossal nerve median nerve plexuses posterior rami posterior roots radial nerve skeletal muscle spinal nerves trochlear nerve Answers will vary.