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Spinal cord is continuous with what?
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together the spinal cord and brain constitute the..?
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Spinal Cord
| Question | Answer |
|---|---|
| Spinal cord is continuous with what? | the brain (specifically the medulla oblongata) |
| together the spinal cord and brain constitute the..? | CNS |
| the CNS | brain and spinal cord |
| shape of spinal cord? length and thickness? | oval-shaped cylinder, about 18 inches long, Bout as thick as your finger |
| spinal cord is covered with..? | the same meninges as the brain |
| in essence, the spinal cord is a ..? | highway. the nerve signals run up and down the spinal cord |
| where does the spinal cord travel down until? | it runs down to the first or second lumbar vertebra. |
| where does the spinal cord lie? | spinal cord lies in the spinal canal (i.e. the vertebral canal). |
| where does the spinal cord leave the skull? | leaves the skull through the foramen magnum (where it is continuous with medulla oblongata) |
| the spinal cord has how many enlargements and where? | it has 2 enlargements when viewed from the back. |
| what are the two spinal cord enlargements? | cervical enlargement and lumbar enlargement |
| cervical enlargement | contains nerves going to and from the upper extremeties |
| lumbar enlargement | contains nerves going to and from the lower extremeties |
| three anatomical parts of the end of spinal cord. | conus medullaris, filum terminale, cauda equina |
| conus medullaris | spinal cord tapers to conical portion at the end. Occurs either at the 1st or 2nd lumbar vertebra. |
| filum terminale | runs from conus medullaris. It is an extension of the pia mater, and attaches the spinal cord to the coccyx to hold it in place. |
| cauda equina (definition and what does it resemble?) | lower spinal nerves leave the vertebral canal lower than the conus medullaris. (Along with the filum terminale it looks like horse's tail) |
| draw the gross anatomy of the end of the spinal cord | conus medullaris is the cord that tapers to conical shape. then a single filum terminale from the point down. then the multiple cauda equina (or lower spinal nerves) fray out from the bottom of conus medullaris (3 on each side of filum terminale, shorter) |
| how many spinal nerves total? | 31 |
| how are the spinal nerves allocated? | 8 cervical nerves, 12 thoracic nerves, 5 lumbar nerves, 5 sacral nerves, 1 coccygeal nerve) |
| draw the spinal nerves in relation to the vertebrae | draw skull, C1 comes out between skull and atlas (C1 vertebra). C8 exits between c7 vertebra and T1 vertebra. T1 nerve exits below the T1 vertebra. |
| how do spinal nerves exit, in general? | spinal nerves exit the vertebral canal through the intervertebral foramina. |
| central canal | space running longitudinally through the length of the spinal cord, contains CSF. continuous with the 4th ventricle |
| lateral horn; where is it present and what does it correspond to? | only present from 2nd thoracic through first lumbar section. Corresponds to the sympathetic nervous system (i.e. the "thoracolumbar nervous system) |
| sympathetic nervous system AKA? | thoracolumbar nervous system |
| what are the horns? what shape do they make in cross section? | the gray matter of the spinal cord. (more cell bodies). makes "H" or butterfly shape in x section |
| what are the columns? what does each column contain? | the white matter of the spinal cord. (more axons and more myelin). each column contains distinct bundles of nerve fibers (tracts) with common origin and destination |
| draw a cross section of spinal cord. label: posterior median sulcus, anterior median fissure, central canal, dorsal horn, lateral horn, ventral horn, dorsal column, lateral column, ventral column, gray commissure, | draw 2 ovals w "H" post median sulc= back depression, ant " fiss= front. central canal= tiny hole. above/below H is dorsal/v column. side of H = lateral c.top and bottom part of H= d/v horn.little bulge on side of H= lateral horn, gray c=surrounds c canal |
| draw x section of spinal cord, label posterior and anterior white and gray commissures. | two ovals with butterfly/H and tiny hole. mark 'X' over H (posterior white commissure) below H= anterior WC, in gray matter above CC= posterior gray commissure, below CC= anterior gray commissure |
| label posterior median sulcus on x section | it is the top sulcus |
| label anterior median fissure | it is the bottom fissure |
| label central canal on x section | tiny hole |
| label dorsal horn on x section | it is posterior, (top part of H) |
| label lateral horn | tiny bulge on side of H |
| label ventral horn on x section | it is anterior, (bottom part of H) |
| label dorsal column | it is posterior. space above H |
| label lateral column on x section | space on side of H |
| label ventral column on x section | it is anterior (space below H) |
| you are a bilateral animal. what does this mean in terms of the spinal cord? | the spinal cord consists of mirror-image lateral gray masses connected by a cross-bar of gray matter: the gray commissure |
| gray commissure | cross-bar of gray matter that connects lateral gray masses |
| where is the central canal, specifically? | in the middle of the gray commissure |
| commissure | crossing over region |
| ascending tracts: main definition, and where do they go to specifically? | carry sensory information up the spinal cord to the brain. go to postcentral gyrus of cerebral cortex (most anterior portion of the parietal lobe).This is the location of the primary sensory cortex of the brain. |
| descending tracts: main definition, and where do they descend from, specifically? | carry motor information down the spinal cord to the body. (sometimes) they descend from the precentral gyrus of cerebral cortex (most posterior portion of frontal lobe). This is the location of the primary motor cortex of the brain |
| how are most ascending tracts named? | names of MOST ascending tracts have the prefix "spino", followed by root denoting the destination of the fibers. (prefix= origin, root=destination) |
| spinothalamic tract | runs from spine to the thalamus. Carries signals for pain, temperature, itch, pressure & tickle |
| spinocerebellar tract | runs from spine to cerebellum. carries info on proprioception from limbs and trunk to the cerebellum |
| proprioception | awareness of body position and movement. |
| give two examples of ascending tracts | spinothalamic tract & spinocerebellar tract |
| explain the pathway of ascending tracts (sensory information) | Typically, ascending tracts (sensory information) has a 3 neuron pathway (info travels across 3 neurons) 1st order neuron, 2nd order neuron, 3rd order neuron |
| 1st order neuron | detects the stimulus using sensory receptors & transmits information to the spinal cord. |
| 2nd order neuron | crosses over to the other side of the spinal cord. Continues up the spinal cord to the thalamus |
| 3rd order neuron | goes from the thalamus to the post-central gyrus of cerebral cortex |
| explain decussation in medullary pyramid in relation to nerve signal destination | because of decussation, signals from fasciculus gracilis & fasciculus cuneatus ultimately end up in contralateral cerebral hemispheres. |
| how are most descending tracts named? | most descending tracts have 'spino' as the root word, with a prefix indicating where its fibers are coming from. |
| descending tracts, carry what? | carry motor signals down the brain stem and spinal cord |
| two examples of descending tracts? | corticospinal tract & reticulospinal tract |
| corticospinal tract | carries information down the spinal cord. This tract Carries signals for precise and finely coordinated limb movements. These tracts form the pyramids |
| reticulospinal tract | originates in reticular formation of the brainstem. This tract carries signals to control muscles of upper & lower limbs, especially for the maintenance of balance and posture |
| spinothalamic tract is what kind? | ascending (sensory) tract |
| spinocerebellar tract is what kind? | ascending (sensory) tract |
| corticospinal tract is what kind? | descending (motor)tract |
| reticulospinal tract is what kind? | descending (motor) tract |
| explain the pathway of descending tracts (motor information) | Typically, descending tracts (motor information) has a 2 neuron pathway (info travels across 2 neurons): upper motor neuron and lower motor neuron |
| upper motor neuron | usually starts in cerebral cortex and goes to brainstem. (some will start in brain stem and go to spinal cord). It synapses with the lower motor neuron |
| lower motor neuron | synapses with the upper motor neuron (in either the brain stem or spinal cord), travels the rest of the way to muscle or other effector/target. |
| nerve | bundle of axons outside CNS. These 'bundles' of fibers form the cord-like organs of the PNS. pearly white in color and decr in size as they travel farther from origin (looks like a "frayed rope" at the end.)can b a few fibers or up 2 a million in a nerve. |
| ganglion | collection of neuronal cell bodies in PNS. Looks like a knot or swelling in the "rope" or nerve. Usually, synapses happen in the ganglia. |
| usually synapses happen in the ganglia. What is the exception to this? | the dorsal root ganglion contains unipolar neuron. So no synapse occurs here. |
| draw a ganglion | just draw two cell bodies with lines and two terminal ends. circle the terminal end w the cell body, this is the ganglion of PNS (coming from CNS |
| nerves can be 1 of three things. what are they? | just sensory, just motor, or mixed (both sensory and motor) |
| just sensory nerves (have only sensory fibers) | i.e. some of the cranial nerves. These are the nerves that control the special senses of smell, sight, hearing, taste & equilibrium |
| just motor nerves (have only motor fibers) | those that go to skeletal muscles |
| mixed nerves | contain both sensory and motor fibers. EX: spinal nerves: carry sensory information toward CNS and motor information away from the CNS |
| neurologists | diagnose and manage spinal cord injuries. |
| what defines a tract? | within any given tract, all nerve fibers have similar origin, destination and function. |
| decussation | information crosses from one side to the other in the spinal cord. This also occurs in the pyramids of medulla oblongata |
| explain the implication of decussation in terms of cerebral hemispheres | so each cerebral hemisphere receives sensory info from and sends motor info to the contralateral side of the body. (stroke on the right = paralysis on left) |
| each cerebral hemisphere receives sensory info from and sends motor info to the contralateral side of the body. What is an exception to this? | however, most cranial nerves carry fibers between the brainstem and ipsilateral receptors and effectors. Same side-so lesion on the same side |
| cranial nerves carry info to ipsilateral sides of body, what is the exception? | cranial II i.e. the optic nerve: only 1/2 of its fibers decussate. |
| most nerves are what kind? | most nerves are mixed nerves, composed of both motor and sensory fibers. |
| two types of motor neurons? | somatic and autonomic |
| Autonomic nervous system is constituted by what? | autonomic motor neurons, together with their central control centers, constitute the autonomic nervous system. |
| somatic motor neurons | are responsible for both reflex and voluntary control of skeletal muscles |
| autonomic motor neurons | innervate the involuntary effectors: (smooth muscle, cardiac muscle and glands). |
| cell bodies of autonomic motor neurons? | the cell bodies of the autonomic neurons (that innervate involuntary effectors) are located outside the CNS in autonomic ganglia. |
| two subdivisions of autonomic motor neurons? | sympathetic and parasympathetic. |
| association neurons AKA? | interneurons |
| interneurons AKA? | association neurons |
| association neurons | located entirely within the CNS and serve the associative, or integrative, functions of the nervous system. |
| innervation | to supply (an organ or other body structure) with nerves. Nerve supply can be either sensory or motor. |
| Nervous System | Detects deviations of the balanced state and then sends messages via nerves to the proper organs to counteract the stress. |
Created by:
kalmetina