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Ch 13 Spine
Spinal Cord, Spinal nerves, and Spinal Reflexes
| Question | Answer |
|---|---|
| posterior median sulcus | longitudinal groove on posterior surface of spinal cord |
| anterior median fissure | groove along the anterior surface of spinal cord |
| cervical enlargement | spinal enlargement that supplies nerves to shoulder and upper limbs |
| lumbar enlargement | spinal enlargement that provides innervation to structures of the pelvis and lower limbs |
| conus medullaris | contains the filum terminales, is conal area located inferior to the lumbar enlargement |
| filum terminale | slender strand of tissue that extends to 2nd sacral vertebrae. Provides longitudinal support to the spinal cord. Component of the coccygeal ligament |
| Dorsal Root Ganglia | portion of each spinal segment that contains cell bodies of sensory neurons |
| Dorsal Roots | bundles of axons of sensory neurons that bring sensory information into the spinal cord. |
| ventral roots | bundles of axons of motor neurons that extend into the periphery to control somatic and visceral effectors |
| Spinal nerve | combination of sensory and motor roots, classifying this nerve as a mixed nerve |
| Cauda Equina | spinal segments L2 to S5, passed the conus medullaris, that resembles a horses tail. Contains both dorsal and ventral roots |
| Three Layers of Spinal Meninges | Dura Mater, Arachnoid mater, and pia mater |
| Dura Mater | outermost layer of the spinal cord |
| Epidural Space | region between canal and dura mater that contains areolar tissue, blood vessels, and adipose tissue |
| Coccygeal Ligament | spinal dura mater that tapers from a sheath to a dense cord and blends with components of the filum terminale |
| subdural space | area that separates the dura mater from deeper meningeal layers. Does not exist in people |
| Arachnoid mater | middle meningeal layer |
| Subarchnoid space | Area in arachnoid mater that is filled with CSF |
| denticulate ligaments | on either side of spinal cord and extend from pia mater to dura mater ligaments that prevent lateral side to side movements |
| Gray Matter Contain ____ | cell bodies of neurons, neuroglia, and unmyelinated axons |
| White matter contain____ | myelinated and unmyelinated axons |
| sensory nuclei | relay and receive sensory info from peripheral receptors |
| motor nuclei | issue motor commands to peripheral effectors |
| Posterior Gray Horns contain ____ | somatic and visceral sensory nuclei |
| Anterior Gray Horns contains | somatic motor nuclei |
| Lateral Gray horns (location and contains____) | located in thoracic and lumbar area only; contains visceral motor nuclei |
| Gray Commissure | area that is posterior and anterior to central canal; contain axons that cross from one side of the cord to the other before reaching gray matter |
| Three regions of white matter on spinal cord | Call Columns or Funiculi: posterior white columns, anterior white columns, and lateral white columns |
| posterior white columns | lie between the posterior gray horns and posterior median sulcus |
| anterior white columns | lie between the anterior gray horns and the anterior median fissure; interconnected by anterior white commissure |
| Anterior White Commissure | area in spinal cord where axons cross from one side to the other |
| Lateral White Columns | white matter between anterior and posterior columns on each side of spinal cord |
| Tract | bundle of axons in the CNS |
| Short tracts carry ___ or ____ between segments of the spinal cord | sensory or motor signals |
| Longer tracts connect ___ with ____ | the spinal cord with the brain |
| Ascending tracts | carry sensory information to the brain |
| Descending tracts | convey motor commands to the spinal cord |
| Epinerium | outermost layer of a neuron; consist of dense network of collagen fibers; site where arteries and veins penetrate |
| Perineurium | the middle layer that extends inward from epineurium; site where arteries and veins branch |
| Endoneurium | innermost layer that surrounds individual axons; site where capillaries leaving th perineurium branch |
| Dermatome | bilateral region of the skin monitored by single pair of spinal nerves; each pair of spinal nerves supplies it's own dermatome |
| peripheral neuropathies | regional losses of sensory and motor function resulting from nerve trauma or compression |
| Nerve Plexus | formed by ventral rami only, complex interwoven network of nerves |
| Four major plexuses | Cervical, brachial, lumbar , and sacral |
| sensory information is collected from ___ structures | peripheral |
| Sensory nuclei locations | thoracic or superior lumbar segmenst of the spinal cord |
| rami that contain sensory fibers | dorsal, ventral, and white rami |
| Sympathetic Nerve carries sensory information from ____ | visceral organs |
| ventral ramus carries sensory information from ____ | ventrolateral body surface, structures of the body wall, and the limbs |
| dorsal ramus carries sensory information from ____ | skin and skeletal muscles of the back |
| dorsal roots of each spinal nerve carry sensory information to ___ | the spinal cord |
| the ventral root of each spinal nerve contains axons of ____ and ____ | somatic motor and visceral motor neurons |
| lateral to the intervertebral foramen | site where dorsal root and ventral root unite |
| Dorsal Ramus contains ____ | somatic motor and visceral motor fibers that innervate the skin and skeletal muscles of the back |
| Ventral ramus supplies ____ | ventrolateral body surfaces, structures in the body wall, and the limbs |
| White ramus communicans contains____ fibers. They carry ____ to _____ | preganglionic; visceral motor fibers to sympathetic ganglion. Note these are only found between T1 and L2 |
| The gray ramus communicans contains ___ fibers. They innervate ____ and ____ in the body wall or limbs | postganglionic; smooth muscles and glands. Note these are associated with each spinal nerve |
| sympathetic nerves contain ___and ___ fibers | preganglionic and postganglionic |
| Cervical plexus | ventral rami of spinal nerves C1-C5; innervate muscles of the neck and into thoracic cavity where diaphragm is controlled |
| Phrenic nerve | major nerve of the cervical plexus that control the diaphragm |
| Brachial Plexus | ventral rami of spinal nerves C5-T1 that innervate pectoral girdle and upper limbs |
| trunks | large bundles of axons from spinal nerves; have superior, middle, and inferior trunks |
| Cords | smaller branches that originate at trunks; have alteral medial, and posterior cords |
| Musculcutaneous nerve | formed by lateral cord |
| Median nerve | formed by medial cord and lateral cord |
| Ulnar nerve | formed by medial cord |
| Axillary nerve and radial nerve are formed by ___ | posterior cord |
| Lumbar plexus | ventral rami of T12-L4; contains nerves genitofemoral, femoral neve, obiturator, and lateral femoral cutaenous nerve |
| Sacral Plexus | ventral rami of spinal nerves L4-S4; contains sciatic nerve and pudenedal nerve |
| Divisions of Sciatic Nerve | Fibular never and tibial nerve; branches as it approaches the knee |
| Sural nerve | formed by branches of fibular nerve that innervates the lateral portion of the foot. Often used for skin grafts |
| neuronal pool | groups of interconnected neurons |
| Sensory neurons deliver information to the ____ | CNS |
| Motor Neurons deliver commands to ____ | peripheral effectors |
| Interneurons | neurons that plan, interpret and coordinate signals in and out; most abundant |
| Five patterns of neural circuitry | Divergence, convergence, serial processing, parallel processing, reverberation |
| Divergence | spread of information from one neuron to several neurons or from one pool to multiple pools in the CNS. Is a broad distribution of a single input |
| Convergence | several neurons synapse on a single synaptic neuron; several patterns having the same effect on postsynaptic neuron |
| Serial Processing | relaying information in a step wise fashion from one neuron to the next; usually occurs relaying sensory information from one part of the brain to another. Moves information in a single line |
| Parallel Processing | several neurons or pools process the same information simultaneously; divergence must take place before parallel processing can occur |
| Reverberation | collateral branches of an axon extend back toward the source and further stimulate the presynaptic neurons. Similar to a positive feedback loop. Continues until synaptic fatigue or until an inhibitory signal is received. |
| Steps of a reflex arc | 1.) Arrival of a stimulus and activation of a receptor 2.) activation of a sensory neurons via graded and action potentials 3.) information processing in the CNS by interneurons 4.) Activation of a motor neuron 5.) Response of a peripheral effector |
| monosynpatic reflexes | sensory neuron synapses with a motor neuron causing the reflex . For example a stretch reflex that involves muscle spindles |
| polysynaptic reflex | reflex that involves interneurons synapsing with motor neurons. For example, withdrawal reflex and crossed extensor reflex (two reflexes on opposite sides happen simultaneously) |
| 4 Classification of relfexes | 1.) their early development, 2.) the nature of the resulting motor response, 3.) the complexity of the neural circuit involved 4.) the site of the information processing |
| Innate reflexes | reflex that resulted during development; genetically programmed |
| Acquired reflexes | learned motor patterns that are more complex and learned over time. Repetition enhances these reflexes |
| Somatic Reflexes | mechanism for involuntary control of the muscular system; superficial reflexes of skin and mucruous and stretch reflexes of tendons and muscles are examples. Overall provides rapid response that can be modified voluntarily later |
| Visceral Reflexes | aka autonomic reflexes; involuntary reflexes that control other systems except muscular |
| spinal reflexes | interconnections and processing that occur in the spinal cord |
| intersegmental reflex arcs | mutliple segments interact to produce a coordinated highly variable motor response. |
| muscle spindles are the ____ of stretch reflexes | receptor |
| intrafusal muscle fibers | small specialized skeletal muscle fiber in muscle spindles |
| extrafusal muscle fibers | large skeletal muscle fibers that surround muscle spindles and contract and rest the muscle tone |
| gamma motor neurons | motor neurons that innervate intrafusal fibers |
| gamma efferents | axons of gamma motor neurons that adjust the sensitivity of the muscle spindle |
| postural reflexes | reflexes that help maintain a normal upright posture |
| tendon reflex | monitor of the external tension produced during contractions to avoid break and tear of tendons. Activated when the tendons are stretched dangerously and inhibits the motor neurons |
| withdrawal reflexes | reflex that moves affected parts of the body away from a harmful stimulus. |
| flexor reflex | withdrawal reflex that affect the muscles of a limb |
| reciprocal inhibition | neurons of the antagonistic muscle are inhibited when the other is stimulated |
| characteristics of polysynaptic reflexes | involve pools of interneurons; intersegmental in distribution; involve reciprocal inhibition; have reverberating circuits that prolong the response; several reflexes may cooperate to produce a coordinated response |
| Axillary nerve | innervates the deltoid and teres minor muscles. C5-C6 |
| genitofemoral nerve | innervates skin over anterior medial thigh and portions of external genitalia for lumbar plexus; L1-L2 |
| lateral femoral cutaneous nerve | innervates skin over anterior, lateral, and posterior thigh under lumbar plexus; L2-L3 |
| femoral nerve | innervates legs skin of anterior medial thigh and medial surface of leg and foot in lumbar plexus; L2-L4 |
| obturator nerve | innervates gracilis, adductor magnus, brevis and longus muscles, and skin from medial surface of the thigh in lumbar plexus; L2-L4 |
| pudendal nerve | innervates muscles of the perineum, skin of external genitalia, bulbosponiosus, and ischiocavernous muscles in sacral plexus; S2-S4 |
| Sciatic nerve | innervates muscles of posterior part of leg, brancehs into tibial and fibular nevres, part of sacral plexus L2-S3 |
Created by:
drubin676